Rozprawy doktorskie: „Herbicide resistance”

1

Kershner, Kellan Scott. "Herbicide resistance in grain sorghum". Diss., Kansas State University, 2010. http://hdl.handle.net/2097/13069.

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Doctor of Philosophy
Department of Agronomy
Kassim Al-Khatib
Mitchell R. Tuinstra
Sorghum acreage is declining throughout the United States because management options and yield have not maintained pace with maize improvements. The most extreme difference has been the absence of herbicide technology development for sorghum over the past twenty years. The objectives of this study were to evaluate the level of resistance, type of inheritance, and causal mutation of wild sorghums that are resistant to either acetyl-coenzyme A carboxylase (ACCase)-inhibiting herbicides or acetohydroxyacid synthase (AHAS)-inhibiting herbicides. ACCase-inhibiting herbicides used in this study were aryloxyphenoxypropionate (APP) family members fluazifop-P and quizalofop-P along with cyclohexanedione (CHD) family members clethodim and sethoxydim. The level of resistance was very high for APP herbicides but low to nonexistent to CHD herbicides. With genetic resistance to APP herbicides, the resistance factors, the ratio of resistance to susceptible, were greater than 54 to 64 for homozygous individuals and greater than 9 to 20 for heterozygous individuals. Resistance to CHD herbicides was very low with resistance factors ranging from one to about five. Genetic segregation studies indicate a single gene is the cause of resistance to APP herbicides. Sequencing identified a single mutation that results in cysteine replacing tryptophan (Trp-2027-Cys). Trp-2027-Cys has previously been reported to provide resistance to APP but not CHD herbicides. The other wild sorghum evaluated in this study was resistant to AHAS-inhibiting herbicides including imidazolinone (IM) family member, imazapyr, and sulfonylurea (SU) family member, nicosulfuron. Resistance factors in this genotype were very high, greater than 770 for the IM herbicide and greater than 500 for the SU herbicide, for both herbicide chemical families. Genetic segregation studies demonstrate that resistance was controlled by one major locus and two modifier loci. DNA sequencing of the AHAS gene identified two mutations, Val-560-Ile and Trp-574-Leu. Val-560-Ile is of unknown importance, but valine and isoleucine are similar and residue 560 is not conserved. Trp-574 is a conserved residue and Leu-574 is a known mutation that provides strong cross resistance to IM and SU herbicides. The results of these studies suggest that these sources of APP, SU, and IM resistance may provide useful herbicide resistance traits for use in sorghum.

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2

Mansooji, Ali Mohammad. "Herbicide resistance in wild oats, Avena spp". Title page, contents and abstract only, 1993. http://web4.library.adelaide.edu.au/theses/09PH/09phm289.pdf.

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Maneechote, Chanya. "Mechanisms of herbicide resistance in wild oats (Avena spp.)". Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phm274.pdf.

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Bibliography : leaves 159-184. This study found at least three mechanisms of resistance to the acetyl coenzyme A carboxylase (ACCase)-inhibiting herbicides. A modified target -site was responsible for moderate and high resistance to herbicides at the whole plant level. Enhanced herbicide metabolism and reduced translocation of herbicide to the target site was observed in one resistant biotype each.

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4

Iwakami, Satoshi. "Molecular mechanism of resistance in a multiple-herbicide resistant Echinochloa phyllopogon". Kyoto University, 2013. http://hdl.handle.net/2433/180368.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第17830号
農博第2015号
新制||農||1016(附属図書館)
学位論文||H25||N4787(農学部図書室)
30645
京都大学大学院農学研究科農学専攻
(主査)教授稲村達也, 教授冨永達, 教授奥本裕
学位規則第4条第1項該当

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5

MacLean, Nancy L. "A study using in vitro selection to develop herbicide resistance in Lotus corniculatus /". Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65376.

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6

Fleitz, Nicholas J. "COMPARISON OF SOIL-APPLIED AND POSTEMERGENCE HERBICIDES WITH MULTIPLE SITES OF HERBICIDAL ACTIVITY ON TWO POPULATIONS OF HERBICIDE-RESISTANT PALMER AMARANTH IN KENTUCKY". UKnowledge, 2018. https://uknowledge.uky.edu/pss_etds/99.

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With the introduction of herbicide resistant Palmer amaranth into Kentucky during the past 10 years there has been an increasing concern for effective control measures in grain production. Field trials were performed in 2016 and 2017 near Barlow and Paris, KY to determine efficacy of chemical control programs targeting herbicide resistant Palmer amaranth. Percent visual control, effects on plant density and plant height were measured in 2016 to determine treatment effectiveness. Treatments containing four different sites of herbicide activity achieved an average of 98% control. Treatments containing only 3, 2 or 1 site of activity only achieved 64%, 45% and 33% control, respectively. Within the long-chain fatty acid inhibitors herbicides in this study, pre-emergent applied pyroxasulfone provided greater control than S-metolachlor or acetochlor. Pyroxasulfone also provided greater control than the photosystem II herbicides atrazine and metribuzin. In 2017 PRE treatments consisting of three-way mixtures of flumioxazin + pyroxasulfone + chlorimuron or S-metolachlor + metribuzin + fomesafen followed by a POST herbicide treatment provided > 90% suppression of Palmer amaranth 4 weeks after trial initiation. Post-emergence treatments containing glyphosate + dicamba or glyphosate + 2,4-D following a soil-applied pre-emergent treatment achieved the most effective season-long control of Palmer amaranth.

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7

Lagator, Mato. "Experimental evolution of herbicide resistance in Chlamydomonas reinhardtii". Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/56830/.

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Our understanding of the evolutionary dynamics of selection for herbicide resistance is limited by the time and space required to conduct meaningful selection experiments in higher plants. This constrains the study of the dynamics of resistance evolution predominantly to mathematical models. The primary goal of this thesis was to overcome these limitations, and to study the evolutionary phenomena underpinning several management strategies. To do so, a series of experimental evolution studies were conducted using Chlamydomonas reinhardtii, a single-‐cell green chlorophyte susceptible to a range of commercial herbicides. In particular, this thesis explored the impact of herbicide sequences, rotations and mixtures, as well the impact of herbicide dose, on evolution of resistance. Applying herbicides in sequence allowed the study of the impact of environmental perturbation on the dynamics of resistance and the associated fitness costs, finding more rapid selection for resistance to a second and third mode of action in some populations. Cycling between herbicides creates conditions of temporal environmental heterogeneity, the outcomes of which are not easily predictable as resistance was slowed down in some cycling regimes, while in others it accelerated the evolution of resistance or gave rise to cross-‐resistance. Herbicide mixtures are a management strategy relying on increases in environmental complexity to provide better control of resistance. The results presented show that mixtures were effective at slowing the evolution of resistance when all mixture components were used at fully effective doses, while low doses of mixtures accelerated resistance evolution and led to more cross-‐resistance. Finally, modifications of the applied herbicide dose allowed the study of local adaptation along an environmental gradient, where the differences in outcomes based on the specific herbicides used were again evident. Overall, the work presented here uses applied scenarios to study the underlying evolutionary phenomena, in order to feed back into the applied thinking.

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8

Milner, Lucy J. "Herbicide resistance in black-grass (Alopecurus myosuroides Huds.)". Thesis, Open University, 2002. http://oro.open.ac.uk/54618/.

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Herbicide resistant grass weeds are a growing problem throughout the UK with Alopecurus myosuroides Huds. (black-grass) considered a major problem in winter cereals. Blackgrass control is hindered by the presence of populations resistant to herbicides. Research indicates that resistance in black-grass is due in part to enhanced metabolism involving glutathione S-transferases (GSTs) and that increased activities of these enzymes may confer resistance in this species. The work described in this thesis has characterised resistance in black-grass and examined the role GSTs play in herbicide resistance with respect to herbicide application and timing. Characterisation of herbicide resistance in three black-grass populations tested against isoproturon, fenoxaprop-P-ethyl, clodinafop-propargyl, sethoxydim, flupyrsulfuron-methyl and AC210 in the glasshouse revealed that the commercially available population, Herbiseed, may be used as a standard susceptible reference population when testing unknown populations. Novel resistance ratings were applied to Herbiseed for future reference. A 2 year study was performed to investigate glutathione S-transferase activity in five UK black-grass populations from field sites situated in the East Midlands. Findings indicate there is a natural elevation of endogenous GST activity in response to black-grass growth and development and natural environmental changes from winter to spring. Clear correlations between GST activity, temperature, solar radiation and sunshine hours have been observed. It is proposed that increasing GST activity is required as part of an antioxidant defence system until tillering (GS30) has ceased. It is speculated that this endogenous change in enzyme activity with plant development in the field contributes to reduced efficacy of some graminicides applied in the spring. Further investigation in a controlled environment focused on the effect of temperature on plant growth and antioxidant status of resistant and susceptible black-grass. Results indicated that temperature has a developmental and metabolic effect on the growth of resistant black-grass plants, which may be critical in the response of plants to herbicide treatment. Increased temperature was accompanied by a natural elevation in endogenous GST activity in resistant plants and changing temperature increased the concentration of antioxidants. It is speculated that these endogenous responses are part of a natural mechanism of acclimation to environmental change in resistant plants of this species and provide protection against subsequent stress such as herbicide treatment. In conclusion, it is postulated that the antioxidant system of black-grass plants is vital for survival under normal plant growth and development and climatic conditions. It is speculated that these endogenous responses are part of a natural mechanism of acclimation to environmental change whilst supporting normal plant development, suggesting that GSTs have direct cytoprotective activity. These observations lend further weight to the suggestion that the development of resistance in black-grass is in part due to evolution and elevation of GST activity. It is speculated that in striving to achieve maximum herbicide efficacy in resistant black-grass populations, the period of environmental change from autumn to winter as temperature decreases, in combination with smaller growth stages of plants would be the best time for graminicide application for black-grass control.

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9

Dick, Rosemary Elaine. "Microbial degradation of the herbicide glyphosate". Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336732.

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Li, Hwei-Yiing. "Mechanisms of action and selectivity of the cyclohexen-one herbicide cycloxydim (BAS 517)". Diss., Virginia Tech, 1990. http://hdl.handle.net/10919/39985.

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The activity and the selectivity of cycloxydim {2-[1-(ethoxyimino)butylJ-3-hydroxy- 5-(2H-tetrahydrothiopyran-3-yl)-2-cyclohexen-l-one}, code designation BAS 517, were examined flIst with etiolated seedlings of com (Zea mays L.) and soybean [Glycine max (L.) Merr.]. Etiolated soybean seedlings were not affected by cycloxydim. The degree of growth inhibition of com varied with concentration of cycloxydim and incubation time. Compared to mesocotyls and coleoptiles, radicles of corn were the most sensitive to cycloxydim. Meristematic tissues appeared to be the site of action of cycloxydim as root meristems were the first to show symptoms. A band of reddening tissue developed at meristematic tips followed by the complete cessation of root growth. In a study comparing activities of technical grade and formulated cycloxydim and sethoxydim, {2-[ l-(ethoxyimino )butyl}- 5-[2-(ethylthio )propy11-3-hydroxy-2-cyclohexen-l-one}, formulated compounds were more potent than the technical grade chemicals without formulation additives. Technical sethoxydim was more potent than technical cycloxydim. Root tips excised from com and soybean seedlings were used subsequently for cycloxydim treatments. The activity and selectivity of cycloxydim expressed at the isolated root tip level were similar to those of cycloxydim bioassayed with whole seedlings. However, root tips appeared to be more sensitive than the whole seedlings. Injury at the tissue and cell levels of the 2-mm root tips that were treated with various concentrations of cycloxydim was examined after 24 hours incubation. Concentrations of 0.1, 1, and 10 μM cycloxydim caused severe cell vacuolization. A gradient of decreasing injury from epidermal cells toward the center of roots was observed. This pattern of injury appeared to reflect the penetration of cycloxydim into roots along a concentration gradient.
Ph. D.

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11

Friesen, Lincoln Jacob Shane. "Identification of the mechanisms of wild radish herbicide resistance to PSII inhibitors, auxinics, and AHAS inhibitors". University of Western Australia. School of Plant Biology, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0106.

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The objective of this Ph.D. research was to identify new and novel mechanisms of wild radish (Raphanus raphanistrum L.) resistance to photosystem II (PSII) inhibitors, auxinics, and acetohydroxyacid synthase (AHAS) inhibitors. PSIIinhibitor resistance was demonstrated to be target-site based, and conferred by a Ser264 to Gly substitution of the D1 protein. Auxinic resistance was associated with reduced herbicide translocation to the meristematic regions of resistant wild radish plants. Two new resistance mutations of wild radish AHAS were discovered, including one encoding the globally rare Asp376 to Glu substitution, and another encoding an Ala122 to Tyr substitution, which has never been identified or assessed for resistance in plants previously. Characterization of the frequency and distribution of AHAS resistance mutations in wild radish from the WA wheatbelt revealed that Glu376 was widespread, and that some mutations of AHAS are more common than others. Computer simulation was used to examine the molecular basis of resistance-endowing AHAS target-site mutations. Furthermore, through the computer-aided analysis, residues were identified with the potential to confer resistance upon substitution, but which have not previously been assessed for this possibility. Results from this Ph.D. research demonstrate that diverse, unrelated mechanisms of resistance to PSII inhibitors, auxinics, and AHAS inhibitors have evolved in wild radish of the WA wheatbelt, and that these mechanisms have accumulated in some populations.

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Dixon, Peter Allan. "Herbicide resistance in wild oats : genetic variation and ecology". Thesis, University of Liverpool, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343857.

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Soar, Christopher J. "Study on the biochemical and physiological basis for resistance to paraquat in Arctotheca calendula (L.) Levyns (Capeweed)". Title page, contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09ACP/09acps676.pdf.

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Scruggs, Eric Brandon. "Control and Fecundity of Palmer Amaranth (Amaranthus palmeri) and Common Ragweed (Ambrosia artemisiifolia) from Soybean Herbicides Applied at Various Growth and Development Stages". Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/98467.

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Palmer amaranth (Amaranthus palmeri) and common ragweed (Ambrosia artemisiifolia) are two of the most troublesome weeds in soybean. Both weeds possess widespread resistance to glyphosate and acetolactate synthase (ALS) inhibiting herbicides resulting in the use of protoporphyrinogen oxidase- (PPO) inhibitors to control these biotypes, although PPO-resistant biotypes are increasing. New soybean herbicide-resistant trait technologies enable novel herbicide combinations. Combinations of two herbicide sites-of-action (SOA) improved control 19 to 25% and 14 to 19% of Palmer amaranth and common ragweed, respectively, versus using one SOA (mesotrione, dicamba, 2,4-D, or glufosinate alone). Seed production of 5 to 10 cm Palmer amaranth and common ragweed was reduced greater than 76% by fomesafen, auxin (dicamba and 2,4-D), or glufosinate containing treatments. Some weeds survived and set seed even when treated at the proper size. As weed size increased from 10 to 30 cm, control diminished and fecundity increased, underscoring the importance of proper herbicide application timing. Effective preemergence herbicides reduced the number of weeds present at the postemergence application compared to no treatment, reducing the likelihood of herbicide resistance development. Dicamba, 2,4-D, or glufosinate applied alone or auxin + glufosinate combinations reduced Palmer amaranth seed production greater than 95% when applied at first visible female inflorescence; this first report, in addition to previous reports on individual herbicides, indicates this application timing may be useful for soil seed bank management. This research informs mitigation of herbicide resistance spread and development.
Master of Science in Life Sciences
Over 30 million hectares of soybeans were harvested in 2019 in the United States, totaling over $31 billion in value. Two of the most troublesome weeds in soybean, Palmer amaranth (Amaranthus palmeri) and common ragweed (Ambrosia artemisiifolia) can cause even greater yield reductions in soybean, up to 79 to 95%, respectively. Frequent, exclusive, and repeated use of a single herbicide has led to multiple herbicide-resistance in both of these weeds. Co-applying two effective herbicides reduces the likelihood of resistance development. New soybean varieties have been genetically modified for resistance to herbicides that were previously unusable, allowing new herbicide combinations. Research was established to investigate these herbicide options to control and reduce seed production of Palmer amaranth and common ragweed with the overarching goal of mitigating herbicide resistance, particularly resistance to protoporphyrinogen oxidase (PPO) inhibiting herbicides, which are a critical part of herbicide options in soybean production. Preemergence herbicides are vital tools in herbicide programs, reducing the number of weeds present at a postemergence application and thereby reducing the risk of herbicide resistance development to the postemergence herbicide. PPO herbicides (flumioxazin, sulfentrazone, or fomesafen) applied preemergence reduced Palmer amaranth and common ragweed density at the postemergence application 82 to 89% and 53 to 94%, respectively. The preemergence herbicide used did not affect control four weeks after the postemergence herbicides were applied. Postemergence herbicides were applied targeting three weed heights: 5 to 10 cm (ideal), 10 to 20 cm, and 20 to 30 cm. Control decreased as weed height increased and larger weeds had greater biomass and seed production, underscoring the importance of proper herbicide application timing. The single site-of-action treatments dicamba, 2,4-D, glufosinate, or fomesafen resulted in greater than 85 and 92% morality of 5 to 10 cm Palmer amaranth and common ragweed, respectively. Palmer amaranth and common ragweed control improved by 19 to 25% and 14 to 19%, respectively, when using two herbicide sites-of-action increased versus using one SOA (mesotrione, dicamba, 2,4-D, or glufosinate alone). The use of two herbicide sites of action resulted in maximum biomass reductions, depending on weed height, of 57 to 96% and 73 to 85% for Palmer amaranth and common ragweed, respectively. Dicamba, 2,4-D, glufosinate alone and in combination with fomesafen reduced seed production (relative to the nontreated) of 5 to 10 cm Palmer amaranth and common ragweed greater than 98 and 76%, respectively. Dicamba, 2,4-D, and glufosinate applied alone or auxin (dicamba and 2,4-D) and glufosinate combinations reduced Palmer amaranth seed production greater than 95% when applied at first visible female inflorescence. This indicates that these herbicides may be useful in soil weed seed bank management. This research reinforces the utility of PPO herbicides for preemergence control and their efficacy postemergence when combined with another effective herbicide, a practice known to reduce herbicide resistance development. This research also reinforces the potential for dicamba, 2,4-D, or glufosinate to reduce weed seed production when applied at a delayed timing. Future research should investigate the progeny of these weeds treated with herbicides at a delayed timing to evaluate the potential for this practice to reduce herbicide resistance development.

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Gomes, Giovanna Larissa Gimenes Cotrick [UNESP]. "Caracterização bioquímica e morfofisiológica de populações de buva (Conyza spp.) resistentes ao glyphosate". Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/116041.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O objetivo deste trabalho foi caracterizar quatro populações de Conyza spp. bioquimicamente e morfofisiologicamente. Os experimentos foram realizados em casa de vegetação com quatro populações (P1, P3 e P4 – Conyza sumatrensis; P2 – Conyza bonariensis) que foram coletados em diferentes municípios do estado de São Paulo. Os tratamentos foram constituídos da aplicação de doses do herbicida glyphosate: 45, 90, 180, 360, 720, 1440, 2880, 5760 e 11520 g e.a. ha-1; e uma testemunha sem aplicação. No momento da aplicação as plantas apresentavam de 5 a 6 folhas totalmente expandidas. Foi realizado um estudo preliminar e mais três estudos, com os mesmos tratamentos, mas com avaliações distintas. O estudo preliminar foi composto de um experimento com a população 4, onde foram avaliados aos 28 dias após os tratamentos (DAT) a altura das plantas, porcentagem de controle, massa fresca de parte aérea, e quantificação dos seguintes compostos por cromatografia líquida de alta eficiência e espectrometria de massas (LCMS/ MS): glyphosate, ácido aminometilfosfônico (AMPA), ácido chiquímico, ácido desidrochiquímico, fenilalanina, tirosina, triptofano, e ácido salicílico. No primeiro estudo foram realizadas as curvas de dose resposta para as quatro populações testadas. No estudo seguinte, aos 14 DAT foi realizada a coleta de todas as folhas de cada planta (repetição) para quantificação dos mesmos compostos já descritos no estudo preliminar, além do ácido indolacético (IAA) e ácido abscísico (ABA) por LC-MS/MS. O último estudo teve como objetivo avaliar o crescimento, florescimento e produção de sementes, por meio de avaliações de altura, número de brotações laterais, número de capítulos abertos e número ...
The objective of this research was to characterize four Conyza spp. populations biochemically and morphophisiologically. The experiments were carried out in a greenhouse with four populations (P 1, 3 and 4 - Conyza sumatrensis; P 2 - Conyza bonariensis). Seeds were collected in different municipalities of the Sao Paulo state. The treatments consisted of the glyphosate application in different doses: 45, 90, 180, 360, 720, 1440, 2880, 5760 and 11520 g ae ha-1 and one untreated control. The herbicide glyphosate was applied to plants with 5-6 expanded leaves. Were performed a preliminary study and three others studies, with the same treatments but with different evaluations. The preliminary study consisted of an experiment with population 4, which was evaluated at 28 days after treatment (DAT) the plant height, percentage of control, fresh weight of plants, and quantitation of glyphosate, aminomethylphosphonic acid (AMPA), shikimic acid, dehydroshikimic acid, phenylalanine, tyrosine, tryptophan, and salicylic acid by LC-MS/MS. In the first study, the dose response curves were performed. In the following study, at 14 DAT, all the leaves of each plant were ...

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Gomes, Giovanna Larissa Gimenes Cotrick 1985. "Caracterização bioquímica e morfofisiológica de populações de buva (Conyza spp.) resistentes ao glyphosate /". Botucatu, 2014. http://hdl.handle.net/11449/116041.

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Orientador: Edivaldo Domingues Velini
Banca: Fernando Tadeu de Carvalho
Banca: Fernando Storniolo Adegas
Banca: Eduardo Negrisoli
Banca: Pedro Jaccob Christoffoleti
Resumo: O objetivo deste trabalho foi caracterizar quatro populações de Conyza spp. bioquimicamente e morfofisiologicamente. Os experimentos foram realizados em casa de vegetação com quatro populações (P1, P3 e P4 - Conyza sumatrensis; P2 - Conyza bonariensis) que foram coletados em diferentes municípios do estado de São Paulo. Os tratamentos foram constituídos da aplicação de doses do herbicida glyphosate: 45, 90, 180, 360, 720, 1440, 2880, 5760 e 11520 g e.a. ha-1; e uma testemunha sem aplicação. No momento da aplicação as plantas apresentavam de 5 a 6 folhas totalmente expandidas. Foi realizado um estudo preliminar e mais três estudos, com os mesmos tratamentos, mas com avaliações distintas. O estudo preliminar foi composto de um experimento com a população 4, onde foram avaliados aos 28 dias após os tratamentos (DAT) a altura das plantas, porcentagem de controle, massa fresca de parte aérea, e quantificação dos seguintes compostos por cromatografia líquida de alta eficiência e espectrometria de massas (LCMS/ MS): glyphosate, ácido aminometilfosfônico (AMPA), ácido chiquímico, ácido desidrochiquímico, fenilalanina, tirosina, triptofano, e ácido salicílico. No primeiro estudo foram realizadas as curvas de dose resposta para as quatro populações testadas. No estudo seguinte, aos 14 DAT foi realizada a coleta de todas as folhas de cada planta (repetição) para quantificação dos mesmos compostos já descritos no estudo preliminar, além do ácido indolacético (IAA) e ácido abscísico (ABA) por LC-MS/MS. O último estudo teve como objetivo avaliar o crescimento, florescimento e produção de sementes, por meio de avaliações de altura, número de brotações laterais, número de capítulos abertos e número ...
Abstract: The objective of this research was to characterize four Conyza spp. populations biochemically and morphophisiologically. The experiments were carried out in a greenhouse with four populations (P 1, 3 and 4 - Conyza sumatrensis; P 2 - Conyza bonariensis). Seeds were collected in different municipalities of the Sao Paulo state. The treatments consisted of the glyphosate application in different doses: 45, 90, 180, 360, 720, 1440, 2880, 5760 and 11520 g ae ha-1 and one untreated control. The herbicide glyphosate was applied to plants with 5-6 expanded leaves. Were performed a preliminary study and three others studies, with the same treatments but with different evaluations. The preliminary study consisted of an experiment with population 4, which was evaluated at 28 days after treatment (DAT) the plant height, percentage of control, fresh weight of plants, and quantitation of glyphosate, aminomethylphosphonic acid (AMPA), shikimic acid, dehydroshikimic acid, phenylalanine, tyrosine, tryptophan, and salicylic acid by LC-MS/MS. In the first study, the dose response curves were performed. In the following study, at 14 DAT, all the leaves of each plant were ...
Doutor

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Welgama, Amali. "Herbicide application strategies for wild radish management in Imidazolinone tolerant faba bean". Thesis, Federation University Australia, 2020. http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/176148.

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The extensive and continual use of herbicides in cropping situations has inevitably led to the phenomenon of "herbicide-resistance" in weeds and this has become one of the most challenging issues in modern agriculture. Herbicide-tolerant crops (HTC) were introduced to diversify weed management practices, but the lack of integrated weed management strategies, along with the continuous use of the same herbicide mode of action (MOA) demanded by the HTC has continued to impose selection pressure on weeds to evolve with herbicide resistance. Consequently, this thesis has been focused on the introduction of herbicide MOA combinations into HTC systems in an attempt to reduce the rate of herbicide resistance evolution in weeds. Raphanus raphanistrum is the number one broadleaf weed in Australia, and for this case study, the newly released ALS-inhibiting imidazolinone tolerant faba bean cultivar PBA Bendoc with its conventional cultivar, PBA Samira, were selected as the study species. ALS-inhibiting (imazamox + imazapyr and imazethapyr) and PSII-inhibiting (metribuzin) herbicides were used as the two herbicide MOAs. The herbicide sensitivity of R. raphanistrum was initially evaluated at different growth stages, in glasshouse studies using herbicide-resistant and susceptible biotypes to ALS-inhibiting herbicides. The highest susceptibility was observed at the earliest growth stage regardless of the biotype and Imazamox + imazapyr proved to be more effective in controlling both biotypes compared to imazethapyr. The same two herbicides were tested on faba bean cultivars at different growth stages to assess crop tolerance and identify the herbicide application window. The field trials conducted in 2018 and 2019 showed increased ALS-inhibiting herbicide tolerance in PBA Bendoc compared to PBA Samira even at the most advanced growth stage. Both faba bean cultivars were then evaluated for their tolerance to metribuzin in-crop application at different herbicide rates. Both cultivars responded similarly, showing progressive herbicide damage with increasing application rates. However, the reduced pod number, even at the lowest rate used, flagged the possible yield penalties that may result in using in-crop metribuzin applications. It is thus suggested that metribuzin must be used post sowing pre-emergent (PSPE) respecting the label recommendations. The potential herbicide combinations were then tested on herbicide-resistant R. raphanistrum and PBA Bendoc to evaluate their efficacies. Metribuzin was initially used as PSPE in all combinations, and was to be followed by imazamox + imazapyr applications at the same growth stages of the weed and the crop as in previous experiments. However, 100% control of R. raphanistrum was achieved using metribuzin alone, and thus no second herbicide was required. All the assessed herbicide combinations were tolerated by PBA Bendoc, proving the suitability of these herbicide combinations for incorporation into the PBA Bendoc cropping system. These results led to two potential herbicide combination strategies: (i) herbicide rotations, with metribuzin as PSPE in one year along with another potential herbicide MOA in the following year, (ii) herbicide sequential application, with metribuzin applied at PSPE and imazamox + imazapyr applied at the 2-4 leaf stage if R. raphanistrum plants survived the metribuzin treatment. A seed germination study was conducted under different temperature/photoperiods, pH levels, osmotic potentials, salinity and burial depths to identify the optimal germination conditions for R. raphanistrum. The optimum germination conditions for both herbicide-resistant and susceptible biotypes of R. raphanistrum were found to be 25ºC/15ºC temperature range under 24 hours complete dark. However, the significant interaction between photoperiod and temperature indicated that the seed germination under higher temperatures is less favoured by 24 hours dark conditions regardless of the biotype. An increased moisture stress tolerance in herbicide-resistant seeds was observed, whilst both biotypes reacted similarly to different pH levels and burial depths. In summary, this thesis has elucidated the effectiveness of two herbicide MOAs in controlling R. raphanistrum while addressing the crop tolerance to these herbicide MOA combinations. These findings will help in setting up stewardship guidelines to be used with the PBA Bendoc faba bean cultivar to mitigate the misuse of herbicides, thus ensuring their sustainable application. In addition, the demonstration of differential seed germination requirements of resistant and susceptible R. raphanistrum seeds has provided further information to help with its systematic management. Overall, this study can be used as a case study to investigate herbicide options that can be used in different HT crop cultivars to control a range of weed species.
Doctor of Philosophy

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Nietschke, Brett Steven. "Integrated strategies for wild oat (Avena spp.) management in southern Australian farming systems". Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phn677.pdf.

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Bibliography: leaves 128-146. Study was undertaken to determine the occurence and species incidence of wild oats in a major cropping region of southern Australia. Population dynamic studies were undertaken at two sites to define the seed bank decline and emergence pattern of several wild oat populations over a three year period. Management studies were conducted to determine appropriate strategies for the control of wild oats in southern Australian farming systems.

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19

Poston, Daniel Hasford. "Growth Analyses and Patterns of Cross-Resistance in Four Imidazolinone-Resistant Smooth Pigweed (Amaranthus hybridus) Populations". Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/29151.

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Studies were conducted in 1996 through 1999 to: (1) evaluate the responses of one imidazolinone (IMI)-susceptible (S) and four -resistant (R1, R2, R3, and R4) smooth pigweed populations to various acetolactate synthase (ALS)-inhibiting herbicides, (2) determine the mechanism of resistance, and (3) evaluate the relative growth and competitiveness of each population. Field studies were conducted in 1996 near Marion, MD, in a field with a history of repeated imazaquin use. Smooth pigweed control with IMI herbicides was < 8 percent, but control with sulfonylurea (SU) herbicides ranged from 73 to 99 percent. Follow-up greenhouse studies were used to confirm IMI resistance in the Marion, MD smooth pigweed population (R4) as well as three others (R1, R2, and R3). R populations were 730- to 1350-fold more tolerant to imazethapyr than the S population. Based on resistance ratios, all R populations displayed low-level cross-resistance to chlorimuron and negative cross-resistance to thifensulfuron, pyrithiobac, and cloransulam-methyl with R2 being the most sensitive of the R populations to pyrithiobac and cloransulam-methyl. Absorption, translocation, and metabolism of ¹⁴C-cloransulam-methyl in S and R2 populations were generally similar. Three metabolites of cloransulam-methyl with ratio of front (Rf) values approximately 0.83, 0.65, and 0.45 were isolated. The metabolite with a 0.83 Rf value increased over time as the parent molecule decreased indicating that it plays a major role in cloransulam-methyl metabolism in smooth pigweed. The other metabolites did not change significantly over time and never represented more than 5 percent of the extracted radioactivity. The identity of these metabolites has not been determined. Using enzyme assays, it was determined that IMI resistance in R populations was due to an altered ALS that was no longer susceptible to inhibition by these herbicides. ALS from S, R1, and R2 populations responded similarly to chlorimuron and thifensulfuron, but reductions in enzyme activity by chlorimuron and thifensulfuron were significantly greater for R3 ALS than for S, R1 or R2 ALS. ALS from R2 and R3 was significantly more sensitive to inhibition by pyrithiobac compared to S ALS. Based on resistance ratios, R2 and R3 ALS were also more sensitive to inhibition by cloransulam-methyl than S ALS. Negative cross-resistance to thifensulfuron, pyrithiobac, and cloransulam-methyl in some R populations at the whole-plant level can be explained by increased sensitivity at the enzyme level. Under noncompetitive conditions in the greenhouse, S produced 17, 23, 25, and 44 percent more biomass than R1, R2, R3, and R4 populations, respectively. S plants were also taller than R plants 17 and 21 d after planting (DAP) and displayed a faster initial rate of leaf area increase compared to all R populations. The net assimilation rate of S was significantly higher than R2 and R3 populations 24 DAP. R3 and R4 populations had significantly less chlorophyll per g of plant tissue compared to S; therefore, reduced growth in some R populations compared to S may be linked to chlorosis that generally appears early in seedling development. Biomass production in the field under competitive conditions was similar for all populations using both monoculture and mixed populations. For this reason, the differences in growth observed in the greenhouse in the S population may not confer a competitive advantage over R populations in the field.
Ph. D.

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Milligan, Andrew Simon. "Wheat biotechnology : engineered herbicide resistance and inducible promoters for transgene expression". Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326968.

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Ulf-Hansen, Peter Fleming. "The dynamics of natural selection for herbicide resistance in grass weeds". Thesis, University of Liverpool, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240807.

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NIÑA, GRACEL BAYLA DIMAANO. "STUDY ON THE METABOLISM-BASED RESISTANCE IN A MULTIPLE HERBICIDE RESISTANT LINE OF Echinochloa phyllopogon (Stapf) Koss". Kyoto University, 2019. http://hdl.handle.net/2433/244561.

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Blyden, E. R. "Molecular genetics of triazine resistance in Senecio vulgaris L". Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383076.

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Krenchinski, Fabio Henrique 1991. "Glufosinate e associações com herbicidas em tecnologias de milho com o gene fosfinotricina acetyltransferase /". Botucatu, 2018. http://hdl.handle.net/11449/155863.

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Orientador: Caio Antonio Carbonari
Coorientador: Alfredo Junior Paiola Albrecht
Banca: Edivaldo Domingues Velini
Banca: Leandro Paiola Albrecht
Resumo: O gene fosfinotricina acetyltransferase (pat) produz a enzima PAT, que por n-acetilação é capaz de metabolizar o glufosinate, transformando-o em n-acetyl-L-glufosinate (NAG). Assim, plantas transgênicas contendo esse gene resistem às aplicações desse herbicida. No milho, esse gene foi inserido como marcador de seleção e mais estudos precisam ser realizados a fim de validar o uso dessa tecnologia. Nesse contexto, os objetivos do presente trabalho foram avaliar se a expressão do gene pat é proporcional ao nível de resistência de tecnologias de milho à aplicação de glufosinate e avaliar a seletividade de herbicidas em associação ao glufosinate em milho com o gene pat. Durante o primeiro trabalho, foram utilizados híbridos de milho com as tecnologias Herculex®; Agrisure TL®; Herculex Yieldgard®; Leptra®; Viptera 3®; Power Core® com o gene pat e VT PRO® sem o gene pat. Para isso, um experimento foi realizado para avaliar a expressão relativa do gene pat nos híbridos de milho, por meio de PCR em tempo real. Em outro estudo, foram aplicadas doses de glufosinate (0, 500, 1000, 2000 e 4000 g i.a ha-1) sobre os híbridos de milho, no qual foram avaliados os teores de glufosinate e NAG, assim como acúmulo de amônia, taxa de transporte de elétrons (ETR), injúria visual e acúmulo de biomassa. Em campo, foi realizada a aplicação de 500 g i.a ha-1 de glufosinate durante o estádio V4 do milho, e foi avaliado o rendimento de grãos. Um segundo estudo foi realizado a campo, adotando-se a tecnolo... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The phosphinothricin acetyltransferase (pat) gene produces the enzyme PAT, which by n-acetylation is able to metabolize the glufosinate, transforming it into n-acetyl-L-glufosinate (NAG). So transgenic plants containing this gene resist the applications of this herbicide. In corn, this gene was inserted as a selection marker and further studies are needed to be performed to validate this technology use. In this context, the objectives of the present work were to evaluate if the expression of the pat gene is proportional to the resistance level of maize technologies submitted to the application of glufosinate and also to evaluate the selectivity of some others herbicides in association with glufosinate in maize which presents the pat gene. For the first work, the technologies used were: Herculex®; Agrisure TL®; Herculex Yieldgard®; Leptra®; Viptera 3®; Power Core® with the pat gene and VT PRO® without the pat gene. For this, an experiment was carried out to evaluate the relative expression of the pat gene in the technologies by RT- PCR. In another study, glufosinate (0, 500, 1000, 2000 and 4000 g a.i ha-1) doses were applied to the technologies, in which the glufosinate and NGA contents, ammonia accumulation, electron transportation rate (ETR), visual injury and biomass accumulation were evaluated. In the field, the spraying of 500 g a.i ha-1 of glufosinate in the V4 stage of maize was carried out in the technologies and grain yield was measured. For the second study the Power Core® technology was adopted, and the experiment was carried out in the field. The treatments were: glufosinate; glyphosate; glufosinate + glyphosate; glufosinate + nicosulfuron; glufosinate + atrazine; glufosinate + tembotrione; glufosinate + mesotrione; glufosinate + carfentrazone ethyl; glufosinate + bentazon; glufosinate + 2,4-D; no-weeding control and weeding control. Evaluations of visual injury, ETR, ammonia ...
Mestre

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Girotto, Marcelo [UNESP]. "Respostas de populações autógamas de Avena fátua à seleção por baixas doses de diclofop-methyl e glyphosate". Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/127907.

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Made available in DSpace on 2015-09-17T15:26:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-05-25. Added 1 bitstream(s) on 2015-09-17T15:45:39Z : No. of bitstreams: 1 000847006.pdf: 350277 bytes, checksum: db6c508303c5e5af00e03576f372683c (MD5)
Se aplicados no estágio e na dose correta, os herbicidas são altamente tóxicos para as plantas. As populações de plantas daninhas suscetíveis a um determinado herbicida são totalmente controladas quando a dose recomendada é corretamente aplicada. No entanto, há uma evolução contínua na sobrevivência e crescimento das plantas em resposta a baixas doses dos herbicidas como resultado da presença de características que podem causar um baixo nível de resistência a estes produtos. Estudos de seleção recorrente podem revelar se a variação fenotípica em resposta a uma dose baixa do herbicida é hereditária e pode conduzir à resistência ao herbicida. Estudos de seleção recorrente de plantas alógamas de Lolium rigidum sobreviventes baixas doses de herbicidas mostraram rápida evolução da resistência a herbicidas em apenas três gerações por intensificação progressiva de características de resistência a herbicidas inicialmente pouco relevantes. Em um estudo de campo, populações autógamas de Avena fatua foram submetidas a um processo de seleção recorrente resultante da aplicação de baixas doses do herbicida diclofop-methyl (inibidor da ACCase) ou o glyphosate (inibidor da EPSPS). As aplicações sucessivas de diclofop-methyl induziram o desenvolvimento de progênies distintas da população original em termos de resistência a este herbicida, com o aumento de duas vezes na LD50. As progênies selecionadas pelo uso de diclofop-methyl também mostraram-se mais resistentes a herbicidas inibidores da ALS indicando sugerindo a ocorrência de resistência cruzada. As aplicações sucessivas de glyphosate não induziram a formação de progênies mais resistentes. A capacidade da A. fatua para responder à pressão de seleção imposta por baixas doses de herbicidas é limitada e muito mais baixa ...
Herbicides when applied at the correct stage and dose are highly toxic to plants. Herbicide-susceptible weed populations are completely controlled at the recommended herbicide label dose. However, there is continuous variation in plant survival and growth in response to herbicide low doses (below-label) because specific plant traits can confer some low level resistance. Recurrent (directional) selection studies can reveal whether such a phenotypic variation in response to a herbicide low dose is heritable and can lead to herbicide resistance. Recurrent selection studies with allogamous cross-pollinated Lolium rigidum plants surviving at a low herbicide dose showed rapid evolution of herbicide resistance in three generations by progressive enrichment of minor herbicide resistance traits. In a common experimental garden study, we have subjected to low-dose recurrent selection a susceptible population of autogamous self-pollinated Avena fatua with the ACCase-inhibiting herbicide diclofop-methyl or the EPSPS-inhibiting glyphosate. Significant differences in response to selection between the selected progenies and parents were evident in the lines selected by low-dose diclofop-methyl, whereas glyphosate selection did not results in significant shifts. A two-fold diclofop resistance was quantified by comparison of estimated LD50 values and a significant increase in survival to ALS-inhibiting herbicides suggests cross-resistance. Importantly, the capacity of A. fatua to respond to low-dose herbicide selection is marginal and much lower than in L. rigidum. The dynamics of selection and the factors driving the evolution of resistance to herbicides in plants are discussed with particular emphasis on the implications of low-dose herbicide use weed management of autogamous self-pollinated vs allogamous cross ...

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Girotto, Marcelo 1984. "Respostas de populações autógamas de Avena fátua à seleção por baixas doses de diclofop-methyl e glyphosate /". Botucatu, 2015. http://hdl.handle.net/11449/127907.

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Orientador: Edivaldo Domingues Velini
Coorientador: Stephen Powles
Coorientador: Roberto Busi
Banca: Caio Antonio Carbonari
Banca: Roberto Estevão Bragion de Toledo
Banca: Ramiro Fernando Lopez Ovejero
Banca: Eduardo Negrisoli
Resumo: Se aplicados no estágio e na dose correta, os herbicidas são altamente tóxicos para as plantas. As populações de plantas daninhas suscetíveis a um determinado herbicida são totalmente controladas quando a dose recomendada é corretamente aplicada. No entanto, há uma evolução contínua na sobrevivência e crescimento das plantas em resposta a baixas doses dos herbicidas como resultado da presença de características que podem causar um baixo nível de resistência a estes produtos. Estudos de seleção recorrente podem revelar se a variação fenotípica em resposta a uma dose baixa do herbicida é hereditária e pode conduzir à resistência ao herbicida. Estudos de seleção recorrente de plantas alógamas de Lolium rigidum sobreviventes baixas doses de herbicidas mostraram rápida evolução da resistência a herbicidas em apenas três gerações por intensificação progressiva de características de resistência a herbicidas inicialmente pouco relevantes. Em um estudo de campo, populações autógamas de Avena fatua foram submetidas a um processo de seleção recorrente resultante da aplicação de baixas doses do herbicida diclofop-methyl (inibidor da ACCase) ou o glyphosate (inibidor da EPSPS). As aplicações sucessivas de diclofop-methyl induziram o desenvolvimento de progênies distintas da população original em termos de resistência a este herbicida, com o aumento de duas vezes na LD50. As progênies selecionadas pelo uso de diclofop-methyl também mostraram-se mais resistentes a herbicidas inibidores da ALS indicando sugerindo a ocorrência de resistência cruzada. As aplicações sucessivas de glyphosate não induziram a formação de progênies mais resistentes. A capacidade da A. fatua para responder à pressão de seleção imposta por baixas doses de herbicidas é limitada e muito mais baixa ...
Abstract: Herbicides when applied at the correct stage and dose are highly toxic to plants. Herbicide-susceptible weed populations are completely controlled at the recommended herbicide label dose. However, there is continuous variation in plant survival and growth in response to herbicide low doses (below-label) because specific plant traits can confer some low level resistance. Recurrent (directional) selection studies can reveal whether such a phenotypic variation in response to a herbicide low dose is heritable and can lead to herbicide resistance. Recurrent selection studies with allogamous cross-pollinated Lolium rigidum plants surviving at a low herbicide dose showed rapid evolution of herbicide resistance in three generations by progressive enrichment of minor herbicide resistance traits. In a common experimental garden study, we have subjected to low-dose recurrent selection a susceptible population of autogamous self-pollinated Avena fatua with the ACCase-inhibiting herbicide diclofop-methyl or the EPSPS-inhibiting glyphosate. Significant differences in response to selection between the selected progenies and parents were evident in the lines selected by low-dose diclofop-methyl, whereas glyphosate selection did not results in significant shifts. A two-fold diclofop resistance was quantified by comparison of estimated LD50 values and a significant increase in survival to ALS-inhibiting herbicides suggests cross-resistance. Importantly, the capacity of A. fatua to respond to low-dose herbicide selection is marginal and much lower than in L. rigidum. The dynamics of selection and the factors driving the evolution of resistance to herbicides in plants are discussed with particular emphasis on the implications of low-dose herbicide use weed management of autogamous self-pollinated vs allogamous cross ...
Doutor

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Pofelis, Shoshana. "The development of sulfonylurea herbicide resistant birdsfoot trefoil (Lotus corniculatus) plants from in vitro selection /". Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60086.

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Birdsfoot Trefoil (Lotus corniculatus L. cv. Leo), is a perennial forage legume that has difficulty in establishing stands due to slow seedling growth, weed competition and herbicide sensitivity. The development of herbicide resistant cultivars would be of economic importance. Resistant lines were isolated after sequential selection at the callus, shoot and whole plant levels to the sulfonylurea (SU) herbicides Harmony (DPX-M6316, code name for methyl 3- ( ( ((4-methoxy-6-methyl-1,3,5,triazine-2-yl)amino) carbonyl) amino) sulfonyl-2-thiophenecarboxylate), or Classic (DPX-F6025, code name for 2(( (4-chloro-6-methoxypyrimidine-yl)amino carbonyl) aminosulfonyl)benzoic acid ethyl ester. In field and growth chamber tests the Harmony regenerant lines displayed an increased tolerance as compared to control plants from tissue culture, and from seed. Results of the evaluation of callus cultures of regenerated mutant lines signify stability of the resistance. Outcrossed seeds collected from field trials, and tested in vitro for herbicide resistance, indicate that the trait is heritable and that resistance may be due to reduced sensitivity of acetolactate synthase to SU inhibition. It is concluded that herbicide resistant birdsfoot trefoil cultivars can be isolated using in vitro selection.

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Godar, Amar Singh. "Glyphosate resistance in kochia". Diss., Kansas State University, 2013. http://hdl.handle.net/2097/16954.

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Doctor of Philosophy
Department of Agronomy
Phillip W. Stahlman
Kochia [Kochia scoparia (L.) Schrad.] is a weed of great economic importance in the Great Plains and western United States and Canada. This weed is prone to evolving resistance to herbicides. Glyphosate is the most widely used herbicide in glyphosate-resistant crops and chemical fallow, and is extremely valuable to crop production. Anecdotal reports of kochia control failure with glyphosate in western Kansas arose during the mid-2000’s. The objectives of this research were to (1) confirm and characterize glyphosate resistance in kochia and measure its impact in western Kansas, (2) gather information on grower weed management practices before and since glyphosate resistance in kochia was confirmed, and (3) determine if altered absorption and translocation of glyphosate contributes to glyphosate resistance in kochia. Dose-response studies on greenhouse and outdoor grown plants, and shikimate accumulation assays confirmed one kochia population collected in 2007 and eight populations collected in 2010 tolerated three- to eleven-times more glyphosate compared to a known glyphosate-susceptible (GS) population. Furthermore, 40 kochia populations collected in 2012 showed varied response, from slightly elevated tolerance to resistance to 0.84 kg ae ha-1 glyphosate. Further analysis suggested these populations were at different stages of resistance evolution. An online survey revealed that growers increased glyphosate use rate and application frequency, but decreased exclusive use of glyphosate and diversified weed management practices during post- compared to pre-glyphosate confirmation periods. Most survey respondents reported presence of glyphosate-resistant (GR) kochia in at least in few fields, and half reported GR kochia in a majority of fields. Thus, together with the resistance confirmation studies, it is estimated that at least one-third of western Kansas kochia populations have evolved resistance to glyphosate. Nominal differences in absorption and translocation of 14C-glyphosate observed between GS and GR kochia populations likely do not contribute to differential response of these populations to glyphosate. Glyphosate-resistant kochia has become widespread in western Kansas in a short period of time. Use of weed resistance best management practices (BMP) is imperative to sustain the utility of glyphosate in the region.

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Sharples, Catherine Ruth. "An investigation of herbicide resistance in black-grass using safeners and synergists". Thesis, Nottingham Trent University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320598.

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Knight, Craig Martin. "Investigating the evolution of herbicide resistance in UK populations of Alopecurus myosuroides". Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/77761/.

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Alopecurus myosuroides, a problematic weed of UK winter cereals, is predominantly controlled by post-emergent herbicides with ALS and ACCase modes of action (MOA). Evolved resistance to these MOA - endowed by the mechanisms of targetsite (TSR) and/or enhanced metabolism (EMR) – threatens the sustainable production of winter cereals in the UK. This project aims to establish the frequency of ALS and ACCase resistance in UK populations of A. myosuroides and the factors that drive its evolution. From a 2011 survey of 92 UK A. myosuroides populations, mesosulfuron-methyl + iodosulfuron-methyl-sodium (ALS) resistance was confirmed in 81 populations; all 92 populations exhibited clodinofop-propargyl (ACCase) resistance. To understand how management affects resistance evolution, seventeen populations from the 2011 survey were resampled (2012–2014) so that estimated frequencies of phenotypic resistance, TSR and EMR could be compared to weed management histories. Fields in which spring crops were more frequently planted possessed A. myosuroides that exhibited lower levels of phenotypic resistance to both ALS and ACCase MOA. A simulation model was developed to describe A. myosuroides herbicide resistance evolution. However, this model could not be validated when parameterized with resistance and management data collected from the UK. In the 2011 survey, homozygous Pro-197-Thr ALS TSR mutations were absent. Phenotyping, germination, and genotyping experiments of plants from controlled heterozygous Pro-197-Thr crosses confirmed that there is a lethality associated with homozygous Pro-197-Thr mutations. To test the hypothesis that preexisting ACCase EMR increases the rate of ALS EMR selection, four A. myosuroides populations – three with ACCase EMR and one without - were selected over two generations with ALS herbicide. From dose-response analyses of survival, the three populations with ACCase EMR exhibited significant increases in ED50 values after selection, whereas the population without ACCase EMR did not.

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Wortley, David. "The role of glutathione transferases in multiple herbicide resistance in grass weeds". Thesis, University of York, 2013. http://etheses.whiterose.ac.uk/4702/.

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Modern agriculture relies on chemical herbicides to control weedy species that compete with crops. In the UK, an estimated 80 % of cropland is infested with the weed species black-grass (Alopecurus myosuroides) that has evolved resistance to multiple herbicides with different modes-of-action. Studies in resistant black-grass identified a phi (F) class glutathione transferase, AmGSTF1, which was constitutively expressed. Heterologous expression of AmGSTF1 in a transgenic host plant granted a multiple herbicide resistant (MHR) phenotype and it was found that the enzyme induced the activities of endogenous detoxification enzymes as well as catalytically detoxifying damaging hydroperoxides in vitro, which can form as a downstream consequence of herbicide treatment. In the current work, AmGSTF1 mutants have been derived and exploited to better understand the function of AmGSTF1 in eliciting MHR. Using a catalytically-retarded mutant, it is shown that the enzyme elicited MHR without requiring catalysis. Instead, the mutant induced the activities of endogenous detoxification enzymes. Another mutant, lacking a cysteinyl residue (Cys120), has demonstrated that Cys120 plays a key role in the interaction of AmGSTF1 with xenobiotics. In particular, Cys120 can be alkylated and inhibited by 4-chloro-7-nitro-benzoxadiazole (NBD-Cl), a compound that can reverse MHR when sprayed on black-grass plants. Enzyme inhibition and alkylation studies found that AmGSTF1 could be alkylated by other chemicals but that this did not induce notable inhibition of the protein. The cysteinyl mutant also induced MHR in a transgenic host plant by inducing the activities of endogenous detoxification enzymes. The properties of AmGSTF1 orthologues from annual rye-grass (Lolium rigidum) and maize (Zea mays) were also explored and found to display very similar functional properties as AmGSTF1. Transcriptome profiling demonstrated that AmGSTF1 did not induce changes in host plant biochemistry by perturbing gene expression. These studies have therefore demonstrated a central regulatory role for GSTF1 enzymes in co-ordinating MHR associated with manipulating host detoxification pathways and challenges the scientific dogma that glutathione transferases require catalytic activity to elicit herbicide resistance.

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Purba, Edison. "Factors influencing the development of resistance to the bipyridyl herbicides in Australia". Title page, contents and abstract only, 1993. http://web4.library.adelaide.edu.au/theses/09PH/09php9852.pdf.

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Bibliography: leaves 143-161. Pot exmeriments are undertaken during the winter growing season to examine Paraquat and Diquat resistance in the grass weed species Hordeum leporinum Link., H. glaucum Steud. and Vulpia bromoides SF Gray, and in the broadleaf weed Arctotheca calendula (L.) Levyns.

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Parrish, Jason Thomas. "Investigations into Multiple–Herbicide-Resistant Ambrosia artemisiifolia (Common Ragweed) in Ohio and Glyphosate-Resistance Mechanisms". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1420789335.

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Hustedde, Nicholas Victor. "Optimum® GAT® Concepts: Herbicide Combinations for Foliar and Residual Weed Control in Soybean and Corn". OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/604.

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Field and greenhouse research was conducted in 2009 and 2010 on herbicide applications enabled by the integration of Optimum GAT crop traits providing for resistance to glyphosate and certain ALS-inhibiting herbicides. The herbicide concepts were evaluated for control of several winter and summer annual weed species, as well as the effect of the resulting weed control on grain yield of Optimum GAT soybean. The combination of chlorimuron + rimsulfuron did not provide sufficient efficacy on the winter annual grass species little barley and annual bluegrass. Factors contributing the sub-lethal activity include: 1) a relatively low inherent sensitivity of the species to these herbicides, 2) a significant reduction in herbicide efficacy with increases in weed plant height, and 3) a lack of herbicide enhancement with more aggressive foliar adjuvants. The tank-mixture of glyphosate with chlorimuron + rimsulfuron was frequently necessary to achieve a maximum herbicide activity above 90% on annual bluegrass and little barley. Optimum GAT herbicide treatments including chlorimuron + rimsulfuron + flumioxazin in field experiments provided the greatest control of horseweed and common waterhemp in glyphosate-susceptible and -resistant populations. The addition of chlorimuron + rimsulfuron to glyphosate and 2,4-D improved horseweed control above glyphosate and 2,4-D applied alone even as weed height increased with applications made closer to soybean planting. However, removal of competitive vegetation with herbicide combinations including chlorimuron + rimsulfuron selected for emergence of ALS-resistant common waterhemp. Inclusion of flumioxazin with chlorimuron + rimsulfuron was beneficial for control of common waterhemp when applied 7 days before planting. However, chlorimuron + rimsulfuron + flumioxazin provided only 80% control of common waterhemp in a glyphosate-resistant population which demonstrates opportunity for improvement in herbicide concepts enabled by Optimum GAT. Grain yield of Optimum GAT soybean was greatest for herbicide treatments which provided effective weed management throughout the growing season which were the herbicide treatments applied the closest to soybean planting (7 days before planting). Optimum GAT herbicide concepts for corn include chlorimuron + thifensulfruon + tribenuron, chlorimuron + rimsulfuron, and rimsulfuron + tribenuron + mesotrione. These herbicides provided similar to slightly increased control of annual morningglory (Ipomoea spp.) in comparison to glyphosate alone. The addition of atrazine increased the consistency of control of annual morningglory for any herbicide treatment with additional residual activity at 28 days after treatment. Optimum GAT enabled herbicide concepts can improve control of some problematic weed species, including some glyphosate-resistant weed populations, compared to current herbicide tactics that rely primarily on glyphosate for weed control in commercial glyphosate-resistant soybean and corn. However, the integration of postemergence soybean herbicides beyond the ALS chemistry is necessary to provide a broader spectrum of weed control when considering the challenges of managing both glyphosate- and ALS-resistant weed species that are becoming more frequent in commercial fields.

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Picoli, Junior Gilmar José 1987. "Influência do glyphosate no perfil bioquímico e fisiológico de populações de azevém (Lolium multiflorum) suscetíveis e resistentes ao herbicida /". Botucatu, 2016. http://hdl.handle.net/11449/135868.

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Orientador: Caio Antonio Carbonari
Coorientador: Edivaldo Domingues Velini
Banca: Giuseppina Pace Pereira Lima
Banca: Eduardo Negrisoli
Banca: Roberto Estevão Bragion de Toledo
Banca: Ricardo Victoria Filho
Resumo: No Brasil, o azevém (Lolium multiflorum) foi identificado como resistente ao glyphosate se tornando um grande problema em determinadas lavouras. Dessa forma, entender o comportamento a nível bioquímico e fisiológico desta planta daninha são ferramentas que auxiliam num manejo eficiente. Com isso, o objetivo deste trabalho foi comparar o perfil bioquímico e fisiológico de populações de azevém suscetíveis e resistentes ao herbicida glyphosate aplicação do mesmo. Foram realizados quatro estudos em casa-de-vegetação com delineamento experimental inteiramente casualizados com quatro repetições sendo semeadas três populações de azevém (Lolium multiflorum) consideradas como suscetível (S), com suspeita de resistência (R1) e resistente (R2) ao herbicida glyphosate. No primeiro estudo foi obtido o controle aos 21 dias após a aplicação (DAA) e quantificada a massa seca aos 28 DAA das três populações. Os tratamentos foram constituídos da aplicação do herbicida glyphosate composto pelas doses: 0, 135, 270, 540, 1080, 2160, 4320, 8640 g e.a. ha-1. O segundo estudo teve como objetivo determinar a atividade da enzima fenilalanina amônia liase (PAL) nas diferentes populações as 12, 24, 48 e 72 horas após a aplicação (HAA). Os tratamentos foram compostos de duas doses (720 g e.a. ha-1 e 1080 g e.a. ha-1) mais uma testemunha sem aplicação. No terceiro estudo foram realizadas avaliações da fotossíntese nas três populações ao 1, 3, 7 e 28 DAA. As variáveis analisadas foram: taxa de assimilação líquida de CO2, condutância estomática, concentração interna de CO2, transpiração, eficiência do uso da água e eficiência instantânea de carboxilação. Os tratamentos foram compostos de duas doses (720 g e.a. ha-1 e 1080 g e.a. ha-1) mais uma testemunha sem aplicação. O quarto estudo teve o objetivo de quantificar compostos alterados da rota do ácido chiquímico. Para ...
Abstract: In Brazil, ryegrass (Lolium multiflorum) was identified as resistant to glyphosate becoming a major problem in certain crops. Thus, understanding the behavior of the biochemical and physiological level of this weed are tools that help in efficient management. Thus, the aim of this study was to compare the biochemical and physiological profile of ryegrass populations susceptible and resistant to glyphosate after spray it. Four studies were carried out in greenhouse with experimental design completely randomized with four replications being seeded three populations of ryegrass (Lolium multiflorum) considered as susceptible (S), suspected of having resistance (R1) and resistant (R2) to the herbicide glyphosate. In the first study was measured the control at 21 days after application (DAA) and at 28 DAA, the dry mass the three populations. The treatments consisted of application of the glyphosate composed of doses: 0, 135, 270, 540, 1080, 2160, 4320, 8640 g a.i. ha-1. The second study aimed to determine the phenylalanine ammonia lyase (PAL) activity in different populations at 12, 24, 48 and 72 hours after application (HAA). The treatments consisted of two doses (720 g a.i. ha-1 and 1080 g a.i. ha-1) plus a control without application. In the third study were carried out photosynthesis assessments at three populations at 1, 3, 7 and 28 DAA. The variables analyzed were: CO2 net assimilation rate, stomatal conductance, CO2 internal concentration, transpiration, water use efficiency and instantaneous carboxylation efficiency. The treatments consisted of two doses (720 g a.i. ha-1 and 1080 g a.i. ha-1) plus a control without application. The fourth study aimed to quantify altered compounds of the shikimic acid pathway. For this, the same treatments of the first experiment were used and made collections of leaves at 5, 11, 28 DAA. The compounds analyzed were: glyphosate, AMPA (aminomethylphosphonic acid) ...
Doutor

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Dallastra, Anderson [UNESP]. "Abordagem multivariada na seleção de progênies de soja superiores e portadoras do gene RR". Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/92647.

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Made available in DSpace on 2014-06-11T19:26:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-07-05Bitstream added on 2014-06-13T20:14:42Z : No. of bitstreams: 1 000738209.pdf: 517669 bytes, checksum: 01eee58693e0de5b0d8e251e6653e038 (MD5)
O melhoramento genético de plantas é considerado um processo complexo que gera múltiplas informações e, em muitos casos, de difícil compreensão. O objetivo deste trabalho foi selecionar progênies com caracteres superiores provenientes de cruzamentos bi-parentais de soja com fonte de resistência ao glifosato (RR), além de identificar cruzamentos e genitores mais eficientes, por meio de abordagens multivariadas. Além disso, objetivou-se ainda testar a eficiência dos métodos no processo seletivo para múltiplos caracteres de interesse. O experimento foi conduzido no delineamento experimental do tipo famílias com testemunhas intercalares, no ano agrícola 2010/2011 e 2011/2012 em Jaboticabal-SP sendo que, nas populações F3 foram selecionadas seis plantas fenotipicamente superiores e avaliadas para os caracteres: número de dias para o florescimento (NDF), número de dias para a maturidade (NDM), altura de inserção da primeira vagem (AIV), altura de planta na maturidade (APM), acamamento (Ac), valor agronômico (VA), número de ramos (NR), número de vagens por planta (NV), peso de cem sementes (PCS), número de sementes por planta (NS) e produção de grãos (PG). Os dados foram analisados utilizando-se o software Statistica 7.0. Os resultados obtidos possibilitaram a seleção de 77 progênies superiores através da Análise de Componentes Principais. A análise de Agrupamentos, pelo do método de K-means, agregou as progênies em seis grupos de acordo com os caracteres de maior importância em cada um e, através do método de Ward, identificou por meio do dendrograma a estrutura de similaridade e divergência entre as progênies selecionadas. Por fim, comparou-se os métodos de agrupamentos e verificou-se que houve concordância entre ambos quanto aos resultados obtidos
The plant breeding is considered to be a complex process that generates multiple information sources and in many cases, difficult to understand. The aim of this work was to select progenies with superior characters from bi-parental crosses with soy source of resistance to glyphosate (RR), and identify intersections and parents more efficient through multivariate approaches. Furthermore, aimed to further test the efficiency of the methods in the selection process for multiple traits of interest. The experiment was conducted in the experimental design of type families to witness progress in the agricultural year 2010/2011 and 2011/2012 in Jaboticabal being that in F3 populations selected six plants were phenotypically superior and evaluated for the traits: number of days to flowering (NDF), number of days to maturity (NDM), height of the first pod (AIV), plant height at maturity (APM), lodging (Ac), agronomic value (VA), number of branches (NR), number of pods per plant (NV), one hundred seed weight (PCS), number of seeds per plant (NS) and grain yield (GY). Data were analyzed using the software Statistica 7.0. The results allowed the selection of 77 superior progenies by Principal Component Analysis. Cluster analysis by the K-means method, all progenies added into six groups according to the characters in each of utmost importance, and by the method of Ward identified by the dendrogram structure similarity and divergence between the progenies. Finally, we compared the clustering methods and found that there was an agreement between them as to the results obtained

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37

Dallastra, Anderson. "Abordagem multivariada na seleção de progênies de soja superiores e portadoras do gene RR /". Jaboticabal, 2013. http://hdl.handle.net/11449/92647.

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Orientador: Sandra Helena Unêda Trevisoli
Coorientador: Antonio Orlando Di Mauro
Banca: Dilermando Perecin
Banca: João Antônio da Costa Andrade
Resumo: O melhoramento genético de plantas é considerado um processo complexo que gera múltiplas informações e, em muitos casos, de difícil compreensão. O objetivo deste trabalho foi selecionar progênies com caracteres superiores provenientes de cruzamentos bi-parentais de soja com fonte de resistência ao glifosato (RR), além de identificar cruzamentos e genitores mais eficientes, por meio de abordagens multivariadas. Além disso, objetivou-se ainda testar a eficiência dos métodos no processo seletivo para múltiplos caracteres de interesse. O experimento foi conduzido no delineamento experimental do tipo famílias com testemunhas intercalares, no ano agrícola 2010/2011 e 2011/2012 em Jaboticabal-SP sendo que, nas populações F3 foram selecionadas seis plantas fenotipicamente superiores e avaliadas para os caracteres: número de dias para o florescimento (NDF), número de dias para a maturidade (NDM), altura de inserção da primeira vagem (AIV), altura de planta na maturidade (APM), acamamento (Ac), valor agronômico (VA), número de ramos (NR), número de vagens por planta (NV), peso de cem sementes (PCS), número de sementes por planta (NS) e produção de grãos (PG). Os dados foram analisados utilizando-se o software Statistica 7.0. Os resultados obtidos possibilitaram a seleção de 77 progênies superiores através da Análise de Componentes Principais. A análise de Agrupamentos, pelo do método de K-means, agregou as progênies em seis grupos de acordo com os caracteres de maior importância em cada um e, através do método de Ward, identificou por meio do dendrograma a estrutura de similaridade e divergência entre as progênies selecionadas. Por fim, comparou-se os métodos de agrupamentos e verificou-se que houve concordância entre ambos quanto aos resultados obtidos
Abstract: The plant breeding is considered to be a complex process that generates multiple information sources and in many cases, difficult to understand. The aim of this work was to select progenies with superior characters from bi-parental crosses with soy source of resistance to glyphosate (RR), and identify intersections and parents more efficient through multivariate approaches. Furthermore, aimed to further test the efficiency of the methods in the selection process for multiple traits of interest. The experiment was conducted in the experimental design of type families to witness progress in the agricultural year 2010/2011 and 2011/2012 in Jaboticabal being that in F3 populations selected six plants were phenotypically superior and evaluated for the traits: number of days to flowering (NDF), number of days to maturity (NDM), height of the first pod (AIV), plant height at maturity (APM), lodging (Ac), agronomic value (VA), number of branches (NR), number of pods per plant (NV), one hundred seed weight (PCS), number of seeds per plant (NS) and grain yield (GY). Data were analyzed using the software Statistica 7.0. The results allowed the selection of 77 superior progenies by Principal Component Analysis. Cluster analysis by the K-means method, all progenies added into six groups according to the characters in each of utmost importance, and by the method of Ward identified by the dendrogram structure similarity and divergence between the progenies. Finally, we compared the clustering methods and found that there was an agreement between them as to the results obtained
Mestre

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Vessabutr, Suyanee. "Transfer of chlorsulfuron resistance from tobacco to birdsfoot trefoil (Lotus corniculatus) by asymmetric somatic hybridization". Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41010.

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A method was developed for rapid plant regeneration from protoplasts of birdsfoot trefoil (Lotus corniculatus cv. Leo) using in vitro cotyledons and a new enzyme formula. Protoplasts of a transgenic Nicotiana tabacum cv. Xanthi line KCR were isolated from leaves, in vitro shoots, and calli by an enzyme formula consisting of 0.5 % Cellulase R-10 and 0.05 % Pectolyase Y23 with either 0.4 M sucrose or 0.5 M mannitol as the osmoticum. Nine asymmetric fusion experiments were conducted between iodoacetate inactivated birdsfoot trefoil and irradiated transgenic tobacco protoplasts. The fusion products underwent several divisions but no visible colonies were obtained. Resistance analyses revealed the inactivation of the herbicide resistant gene in the transgenic tobacco calli. A putative chlorsulfuron resistant line has been obtained by in vitro selection from birdsfoot trefoil cotyledonous protoplasts. Their regenerants had normal ploidy, and expressed improved tolerance when sprayed with chlorsulfuron at the rate of 30 g/ha.

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Mohapatra, Umaballava. "Introduction and expression of transgenes in lettuce (Lactuca sativa L.)". Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243641.

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Reiners, Stephen. "Selectivity of thiobencarb between two lettuce (Lactuca sativa, L.) cultivars /". The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487329662145846.

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Cutts, Todd Andrew. "Herbicide resistance enriched hybrid and synthetic seed production and performance in Brassica rapa". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ51700.pdf.

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Schwarz, Maria. "Exploring the molecular basis of multiple herbicide resistance in black grass (Alopecurus myosuroides)". Thesis, Durham University, 2017. http://etheses.dur.ac.uk/12318/.

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Modern agriculture couples the management of invasive weed species with enhancing crop yields through the intensive use of herbicides. As a result of herbicides being the primary method of weed control in agronomic crops, herbicide resistance has evolved and there has been a vast increase in the occurrence and distribution of herbicide resistant weeds. Many of the most problematic weeds have now evolved multiple herbicide resistance (MHR), which is associated with an enhanced ability to detoxify xenobiotics, enabling the weed to survive herbicide application irrespective of the mode of action. As herbicide resistance is a major limiting factor to food security in global agriculture, effective methods for weed management are sought. This work focuses on MHR in black grass (Alopecurus myosuroides), one of the most damaging weeds of winter cereals. Previous work by Edwards et al. described that black grass populations showing MHR, exhibit an upregulation in the expression of a specific phi-class glutathione transferase (AmGSTF1), which is thought to have a direct regulatory control on metabolism. The importance of AmGSTF1 in MHR has been confirmed both genetically by transgene experiments and chemically through inhibition experiments. This offers the opportunity to develop potential herbicide synergists, which are active towards AmGSTF1 and restore herbicide control in multiple herbicide resistant black grass. Considering the rapid spread of MHR in grass weeds and the limited development of new herbicides, synergists offer an important alternative strategy in counteracting resistance in the field. Recently a new class of AmGSTF1 inhibitors, derived from flavonoids, could be identified. Initial efforts focused on the synthesis of a series of flavone analogues, mainly with structural changes of the C-ring and different substituents in the 5-position. A particular emphasis was put on increasing the aqueous solubility and other physicochemical properties of the compounds, in order to increase the bioavailability in the plant. Although the potency of the initial lead molecule could not be increased in vitro, 5,7-dimethoxy-2-(1’,3’-thiazol-2’-yl)-4H-chromen-4-one, with a significantly increased aqueous solubility, showed good results in in vivo studies in black grass and acted as a synergist to the herbicide pinoxaden. The black grass plants died, when pinoxaden (10μl of a 15 μM solution) was applied to plants, which were pre-treated with the thiazole (10 μl of a 2 mM solution), but survived the herbicide treatment, if no synergist was applied prior.

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Puri, Atul. "Biochemical, molecular, and physiological aspects of fluridone herbicide resistance in hydrilla (Hydrilla verticillata)". [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0013738.

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Mascanzoni, Elisa. "Epidemiology of herbicide resistance evolution in rice weeds and variability in Echinochloa spp". Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3425887.

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Resistance issues has geometrically increased in the last ten years and now are affecting the production of all most important crops worldwide. Italy is the first European rice producer with about 230,000 ha cultivate mostly in the north west of the Po Valley. To date six weeds have evolved resistance in this crop, among these the most troublesome is Echinochloa spp. Two main purposes were followed in the research: first it was performed an epidemiological study at a scale as large as the main rice area, second a classification study was done on Echinochloa spp. including a dose response experiment of different species belonging to this genus to herbicides. The aim of epidemiological study was to investigate, at municipality level, the association between herbicide resistance cases identified so far and three important agronomic predictors: water seeding rate, soil texture and rotation rate. The analyses was performed using different statistical tests: discriminant analyses and logistic regressions were used to find the degree of association between resistance presence and the predictors. Neural Network approach was used to calculate the risk of resistance evolution on the base of the predictors. Neural Network was able to predict the evolution of resistance in 70% of municipalities when all 6 resistant weeds were considered in the analyses, 30% when Echinochloa spp. alone was considered, losing part of its predictive power maybe due to the smaller quantity of resistance cases present in the database. Maps in Qgis were composed to graphically display the diffusion of the three predictors in the area of the study and the risk of resistance evolution. A resistance screening was performed on 20 randomly collected populations of Echinochloa spp in the area where GIRE had never recorded resistant cases. 16 populations resulted resistant to ALS+ACCase showing that in in these areas resistance is present, but kept at an acceptable level for the farmers. The second part of the research was focused on the recognition of Echinochloa species, matching already published dichotomical keys, with molecular discrimination performed through DNA barcoding approach. Forty accessions of Echinochloa spp. were collected in 2015 from single plant, they were classified and tested for penoxsulam sensitivity. Among the sensible accessions ten were chosen for reproduction in order to obtain a bigger quantity of seeds for further studies. Penoxsulam screening was repeated on these accessions to confirm sensitivity. Morphological classification and molecular marker discrimination were performed both on original and reproduced accessions, with consistent results. Results show that according to Costea & Tardif (2002) only E. crus-galli and E. oryzicola were present among our accessions, according to Tabacchi et al. (2006) there were E. crus-galli, E. oryzicola and E. phyllopogon. Five DNA regions of the chloroplast were analyzed: matK was able to highlight genetic differences between the “white” species, besides distinguishing E. crus-galli, providing a good, but not complete match with Tabacchi et al. (2006) classification. rbcL region instead, differentiating only E. oryzicola from E. crus-galli provided a 100% match with Costea & Tardif (2002) classification. A Specie-Specific PCR protocol was set up on matK gene to discriminate among the “white” Echinochloa species in a single PCR reaction. Dose response experiment was performed twice on 9 accessions using three different herbicides: cyhalofop – butyl, penoxsulam and florpyrauxifen benzyl, both in greenhouse and in outside conditions: although results were variable, especially in the outside experiment, it was clear that the three herbicides had similar efficacy on all Echinochloa species. Results obtained show that planning herbicides strategies on the base of the Echinochloa spp. present on field could be wrong.
La resistenza agli erbicidi è un problema che è cresciuto esponenzialmente negli ultimi 10 anni e riguarda tutte le più importanti colture al mondo. L’Italia è il primo produttore europeo di riso con 230.000 ha localizzati nel nord-ovest della Pianura Padana. Ad oggi 6 infestanti hanno evoluto popolazioni resistenti in riso in Italia, fra queste la più importante è Echinochloa spp. La ricerca si è svolta su due binari paralleli: il primo è uno studio epidemiologico a larga scala sulla principale area riso, il secondo è uno studio sulla classificazione di Echinochloa spp. che comprendente esperimenti di dose risposta su varie specie di Echinochloa spp.agli erbicidi. Obiettivo dello studio epidemiologico era analizzare, a livello comunale, il grado di associazione fra presenza di resistenza e tre importanti predittori agronomici: percentuale di semina in acqua, tessitura del suolo e percentuale di rotazione. Le analisi sono state fatte con più approcci statistici: l’analisi discriminante e la regressione logistica hanno permesso di individuare un alto grado di associazione fra la presenza di resistenza ed i predittori. L’approccio Neural Network ha permesso di calcolare il rischio di evolvere popolazioni resistenti sulla base dei predittori: 70% quando tutte le infestanti resistenti sono state considerate, 30% quando solo i casi di Echinochloa spp. sono stati inclusi, perdendo parte del potere predittivo forse a causa della minore quantità di casi di resistenza inclusi nel database. In Qgis sono state create mappe per illustrare la diffusione dei tre predittori nell’area dello studio e il rischio di evoluzione della resistenza. 20 popolazioni di giavone sono state raccolte nei comuni dove non sono mai stati segnalati casi di resistenza al GIRE ed è stato fatto uno screening. 16 popolazioni sono risultate resistenti ACCase+ALS mostrando che in queste aree la resistenza è presente, ma viene tenuta ad un livello accettabile per gli agricoltori. La seconda parte della ricerca riguardava la classificazione delle diverse specie di giavone, abbinando la classificazione fenotipica alla discriminazione fatta attraverso marcatori molecolari usando il DNA barcoding. 40 accessioni di giavone sono state raccolte da piante singole nel 2015, sono state classificate morfologicamente e testate per la sensibilità al penoxsulam. Fra le piante sensibili, 10 sono state riprodotte per ottenere una quantità maggiore di seme. Lo screening con il penoxsulam è stato ripetuto sulle accessioni riprodotte a confermare la sensibilità. La classificazione morfologica e la discriminazione per marcatori molecolari sono state fatte sia sulle piante originali che sulle riprodotte, dando risultati consistenti: nelle popolazioni riprodotte usando Costea & Tardif (2002) sono presenti solo E. crus-galli ed E. oryzicola, usando Tabacchi et al. (2006) sono presenti E. crus-galli, E. oryzicola ed E. phyllopogon. Sono state analizzate 5 regioni di DNA cloroplastico: matK ha discriminato fra le diverse specie di giavone bianco, oltre a E. crus-galli offrendo un buon match, anche se incompleto, con la classificazione di Tabacchi et al. (2006). Le sequenze di rbcL invece hanno differenziato solo E. oryzicola da E. crus-galli, corrispondendo perfettamente a Costea & Tardif (2002) Un protocollo di PCR specie-specifica è stato impostato su matK gene per discriminare diverse specie di giavoni bianchi in una sola reazione di PCR. Gli esperimenti di dose-risposta sono stati fatti sia in serra che all’aperto su 9 accessioni con 3 erbicidi: cyhalofop – butyl, penoxsulam e florpyrauxifen benzyl: anche se i risultati sono stati variabili, soprattutto nell’esperimento all’aperto, è chiaro che i vari erbicidi hanno efficacia simile su tutte le specie di Echinochloa. I risultati ottenuti dimostrano che pianificare le strategie erbicide sulla base delle diverse specie di Echinochla possa essere erroneo.

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Rey, Caballero Jordi. "Unravelling herbicide resistance in corn poppy (Papaver rhoeas L.) to improve integrated weed management strategies". Doctoral thesis, Universitat de Lleida, 2016. http://hdl.handle.net/10803/382633.

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La presencia de biotipos de amapola (Papaver rhoeas L.) resistentes a herbicidas constituye uno de los principales problemas de muchas áreas cerealistas de secano. La solución del mismo pasa por una correcta caracterización de la resistencia y por el establecimiento de una adecuada estrategia de manejo integrado. El presente trabajo se ha planteado precisamente con este fin. Para ello a) se han seleccionado biotipos con resistencia múltiple (a inhibidores de la acetolactato sintasa -ALS- y a herbicidas auxínicos) y biotipos únicamente resistentes a 2,4-D originarios de las zonas cerealistas del noreste peninsular de los que se han estudiado las bases moleculares y fisiológicas de estas resistencias; b) se ha querido discernir bajo condiciones controladas (invernadero), si los fallos de control observados en campo, mediante herbicidas inhibidores del fotosistema II (bromoxinil), son debidos al estadio fenológico de la mala hierba en el momento de aplicación o a la presencia de una posible resistencia incipiente y c) se han establecido diferentes estrategias de manejo integrado de amapola en campos comerciales de cereales de secano del noreste peninsular.
La presència de biotips de rosella (Papaver rhoeas L.) resistents a herbicides constitueix un dels principals problemes de moltes àrees cerealistes de secà. La solució del mateix passa per una correcta caracterització de la resistència així com en l'establiment d'una adequada estratègia de maneig integrat. El present treball s'ha plantejat precisament amb aquesta finalitat. Per això a) s'han seleccionat biotips amb resistència múltiple (a inhibidors de la acetolactato sintasa -ALS- i a herbicides auxínics) i biotips únicament resistents a 2,4-D originaris de les zones cerealistes del nord-est peninsular i s’han estudiat les bases moleculars i fisiològiques d'aquestes resistències; b) s'ha volgut discernir sota condicions controlades (hivernacle), si la manca de control observada en camp, mitjançant herbicides inhibidors del fotosistema II (bromoxinil), és deguda a l'estadi fenològic de la mala herba en el moment de l’aplicació o a la presència d' una possible resistència incipient i c) s'han establert diferents estratègies de maneig integrat de rosella en camps comercials de cereals de secà del nord-est peninsular.
The persistence of resistant corn poppy (Papaver rhoeas L.) biotypes is one of the most pressing problems in rainfed Spanish cereal crops. Resolution to this problem begins with the proper characterization of the resistant profile, followed by the establishment of an appropriate integrated management system. The study herein has been conducted precisely towards this end, while maintaining the following bases as a general framework: a) corn poppy biotypes with multiple resistance (acetolactate synthase -ALS- inhibiting herbicides and auxinic herbicides) and only 2,4-D resistance from north-eastern Spain were selected for analysis of molecular and physiological resistance matrices; b) we have tried to investigate under controlled conditions, if failures observed in the field, by photosystem II inhibiting herbicides (bromoxynil), could be directly attributed to the phenological stage of the weed at application time or inherent resistance and c) the creation of integrated management strategies for corn poppy and rainfed cereal fields in North-Eastern Spain.

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Ahmed, Amro Mohamed Aly Tawfic. "Control, Assessment and Glyphosate Resistance of Palmer Amaranth(Amaranthus palmeri S. Wats) in Virginia". Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/34563.

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Glyphosate resistant crops were rapidly adopted by farmers since their introduction in 1996 and currently, greater than 90% of cotton and soybean crops are glyphosate resistant. Glyphosate has been an effective mean for controlling Palmer amaranth, however overreliance on glyphosate based systems resulted in weeds that can no longer be controlled with glyphosate. Palmer amaranth resistance to glyphosate has been confirmed in ten US states including Virginiaâ s bordering neighbor North Carolina. The objectives of this study were to i) determine the spread of Palmer amaranth and evaluate awareness among farmers and agribusinesses of herbicide resistant weeds in Virginia; ii) determine the efficacy of commonly used cotton and soybean herbicides programs for Palmer amaranth control; and iii) conduct greenhouse experiments to quantify the level of glyphosate resistance in a Greensville County, Virginia population. Using a communication network of Virginia county extension agents and crop advisers, Palmer amaranth was found in 15 Virginia counties. A survey was conducted to evaluate awareness of herbicide resistance and management of weeds in Virginia. Ninety percent of producers had fields planted to Roundup Ready^® crops for each of the last 3 years. One hundred percent of the responders claimed awareness of the potential for weeds to develop resistance to glyphosate, but when asked about how serious they consider weed resistance to herbicides, the responders average rating was of 7.9 (on a scale of 1 to 10 where 1 is â not at all seriousâ and 10 is â very seriousâ ). Eighteen percent of the responder population claimed no awareness of glyphosate resistant weeds

documented in Virginia. Herbicide efficacy experiments were established in soybean and cotton fields infested with Palmer amaranth. In soybean, experiments were established in a field where Palmer amaranth was not adequately controlled with glyphosate in the previous year. Glyphosate applied at 0.87 + 0.87 + 1.74 kg ae ha^-1 at 1, 3, and 5 weeks after planting (WAP) provided 82 to 85% control in 2009, but only 23 to 30% control in 2010, a hot and dry year. Glyphosate applied after preemergence (PRE) herbicides improved control to 90 percent. Programs that included s-metolachlor + metribuzin applied preemergence and followed by glyphosate + fomesafen applied postemergence provided the best control (93%) at 8 WAP. Glufosinate based herbicide programs provided greater than 85% control when applied alone, and control increased to 95% when preceded by PRE herbicides. Many conventional control systems integrating different modes of action provided more than 80% control at final evaluation of Palmer amaranth in 2009 and 2010. In soybean, the most consistent and effective program was flumioxazin applied PRE followed by chlorimuron + thifensulfuron, which provided 99 and 82% control at final evaluation in 2009 and 2010, respectively. Cotton fields were heavily infested with Palmer amaranth, but control with glyphosate had historically been good. Glyphosate applied early postemergence, late postemergence, and late post-directed provided more than 95 percent control at final evaluation of Palmer amaranth. Preemergence applications of fomesafen, fluometuron, or pendimethalin + fomesafen provided 77 to 99 percent early-season control and control was complete with an additional postemergence glyphosate application. Glufosinate applied at 0.45 kg ha^-1 at 1 and 3 WAP or applied at 0.45 kg ha^-1 following a preemergence herbicide provided greater than 95% control. Greenhouse experiments confirmed Palmer amaranth resistance in a population collected from Greensville County, Virginia. In the first experiment, the resistant biotypeâ s I₅₀value (rate necessary for 50% inhibition) for dry weight was 1.47 kg ae ha^-1, which is 4.6 times greater than the susceptible biotype and 1.7 times the recommended use rate of glyphosate. For fresh weight, the I₅₀value of the resistant biotype was 1.60 kg ae ha^-1, 4.7 times that of the susceptible biotype of 0.34 kg ae ha^-1. In the second experiment, the I₅₀ value for the susceptible population could not be determined because all glyphosate rates resulted in complete control. However, the resistant population required 1.01 and 1.30 kg ae ha^-1of glyphosate to reduce the fresh and dry weight by 50%.

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Bianchi, Leandro 1991. "Efeito de glyphosate e clethodim isolados e em mistura em Digitaria insularis /". Botucatu, 2018. http://hdl.handle.net/11449/153555.

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Orientador: Edivaldo Domingues Velini
Banca: Leandro Tropaldi
Banca: Lucas Perim
Resumo: Devido ao uso frequente do glyphosate na agricultura, o capim-amargoso (Digitaria insularis) tornou-se uma das plantas daninhas mais problemáticas no Brasil, por adquirir resistência a esse herbicida. Biótipos resistentes em estádios iniciais são facilmente controlados por graminicidas, porém em estádio mais avançado o controle é reduzido. O herbicida clethodim é um graminicida com alta eficiência, portanto, verificar o controle de biótipos resistentes ao glyphosate em diferentes estádios, com o uso isolado de clethodim e em mistura com o glyphosate é fundamental para auxiliar no manejo desta invasora. Assim o presente trabalho teve como objetivo avaliar o desempenho de glyphosate, clethodim e glyphosate + clethodim, em biótipo de D. insularis resistente e suscetível. O ensaio foi realizado em casa de vegetação, inteiramente casualizado, com quatro repetições e repetido em duas épocas do ano. As aplicações foram realizadas em estádio inicial (15 - 20 cm) e em florescimento. Avaliou-se o controle aos 21 dias e o peso da biomassa seca. Para a mistura dos produtos, foi verificada a interação entre os herbicidas: efeito sinérgico, antagônico ou aditivo. No ensaio com plantas em estádio inicial, avaliou-se a concentração de lipídeos na biomassa seca. De forma geral, a aplicação de clethodim aplicado isoladamente controlou o biótipo resistente em estádio inicial, porém em florescimento a eficácia foi reduzida. A mistura mostrou-se eficiente para controle de biótipo resistente em es... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Due to frequent use of glyphosate in agriculture, sourgrass (Digitaria insularis) has become one of the most problematic weeds in Brazil for purchase resistance to this herbicide. Resistant biotypes in initial stages are easily controlled by graminicides, but in a more advanced stage the control is reduced. The herbicide clethodim is a graminicide with high efficiency, therefore, to check the control of resistant biotypes of glyphosate in different stages, with the isolated use of clethodim and in mixture with the glyphosate is fundamental to assist in the management of this weed. Thus the experiment was aimed at evaluate the action of glyphosate, clethodim and glyphosate + clethodim, in a resistant and susceptible biotype of D. insularis. The experiment was carried out in a greenhouse, completely randomized, with four replications and repeated at two times of the year. The applications were performed in the initial stage (15 - 20 cm) and flowering. Plants were evaluated at 21 days after application (DAA) and dry biomass weight. For the mixture of products, the interaction between the herbicides was also verified: synergistic, antagonistic or additive effect. In the experiment with plants at the initial stage, was evaluated the lipid concentration in the dry biomass. In general, the application of clethodim applied alone controlled the resistant biotype at the initial stage, but in flowering the efficiency was reduced. The mixture showed to be efficient for control of resistant biotype in initial and flowering stages. Considering the visual evaluations of control, the interaction between glyphosate and clethodim showed synergic effect for intermediate doses and additive for the highest doses considering the initial stage; in flowered plants, with the additive effects predominating for all as doses, the additive effect prevailed for all doses. For dry mass, the mixture had synergistic interaction ...
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Massa, Dario [Verfasser], i Roland [Akademischer Betreuer] Gerhards. "Investigations on herbicide resistance in Apera spica-venti populations / Dario Massa. Betreuer: Roland Gerhards". Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2012. http://d-nb.info/1027352812/34.

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Straker, Hannah Elizabeth. "Chemical methods towards the investigation of multiple herbicide resistance in black grass (Alopecurus myosuroides)". Thesis, Durham University, 2014. http://etheses.dur.ac.uk/10822/.

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As the world population rises and the availability of land for cultivation decreases, there is an ever-growing demand on food production. However, the persistent use of herbicides in order to sustain food production has resulted in the emergence of resistance. The most serious form of resistance is multiple herbicide resistance (MHR) in which plants become resistant to all herbicides regardless of their mode of action. Previous work involving the weed black grass identified a key glutathione S-transferase (GST), AmGSTF1, involved in the development of MHR. Small molecule inhibitors of the benzoxadiazole motif have been shown to disrupt the function of this enzyme and consequently suppress resistance. This work describes the synthesis of 4-substituted-7-nitrobenzofurazan derivatives and structurally related 6-halopurine analogues to investigate SAR. Assessment of these compounds through in vitro and in vivo studies revealed that alkoxy and thiol leaving groups were preferred for activity in the benzofurazan series, whilst 8-substituted-6-halopurine analogues were favoured in the purine series. However, no significant enhancement in activity over the parent structures was observed with these pharmacophores. Further studies identified a new class of small molecule inhibitors through ligand fishing in which AmGSTF1 was immobilised on a streptactin column and washed with a cocktail of inhibitors. This method revealed flavonoid compounds to be potent binders of AmGSTF1. The subsequent synthesis and SAR evaluation of flavones highlighted 5,7-dihydroxyflavone as a key pharmacophore. Additional work revealed a fatty acid quercetin derivative to be a potent inhibitor of AmGSTF1, and was subsequently shown to be capable of synergising the effects of herbicides in MHR black grass.

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Nakka, Sridevi. "Physiological, biochemical and molecular characterization of multiple herbicide resistance in Palmer amaranth (Amaranthus palmeri)". Diss., Kansas State University, 2016. http://hdl.handle.net/2097/34474.

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Doctor of Philosophy
Department of Agronomy
Mithila Jugulam
Palmer amaranth (Amaranthus palmeri) is one of the most aggressive, troublesome and damaging broadleaf weeds in many cropping systems including corn, soybean, cotton, and grain sorghum causing huge yield losses across the USA. As a result of extensive and intensive selection of pre- and -post emergence herbicides, Palmer amaranth has evolved resistance to multiple herbicide modes of action, microtubule-, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS)-, acetolactate synthase (ALS)-, photosystem II (PS II)-, hydroxyphenylpyruvate dioxygenase (HPPD)- and more recently to protoporphyrinogen oxidase (PPO)-inhibitors. A Palmer amaranth population from Kansas was found resistant to HPPD-, PS II-, and ALS-inhibitors. The overall objective of this research was to investigate the target-site and/or non-target-site resistance mechanisms in Palmer amaranth from KS (KSR) to mesotrione (HPPD-inhibitor), atrazine (PS II-inhibitor), and chlorsulfuron (ALS-inhibitor) relative to known susceptible Palmer amaranth from Mississippi (MSS) and KS (KSS). Whole plant dose-response assays showed high level of resistance in KSR to mesotrione, atrazine and chlorsulfuron. KSR was 10-18, 178-237 and >275 fold more resistant to mesotrione, atrazine, and chlorsulfuron, respectively, compared to MSS and KSS. Metabolism studies using [¹⁴C] labeled mesotrione and atrazine demonstrated non-target-site resistance to both herbicides, particularly, enhanced metabolism of [¹⁴C] mesotrione likely mediated by cytochrome P450 monooxygenases and rapid degradation of [¹⁴C] atrazine by glutathione S-transferases (GSTs). In addition, molecular and biochemical basis of mesotrione resistance was characterized by quantitative PCR (qPCR) and immunoblotting. These results showed 4-12 fold increased levels of the HPPD transcript and positively correlated with the increased HPPD protein. Sequencing of atrazine and chlorsulfuron target genes, psbA and ALS, respectively, showed interesting results. The most common mutation (serine264glycine) associated with atrazine resistance in weeds was not found in KSR. On the other hand, a well-known mutation (proline197serine) associated with chlorsulfuron resistance was found in 30% of KSR, suggesting ~70% of plants might have a non-target-site, possibly P450 mediated metabolism based resistance. Over all, KSR evolved both non-target-site and target-site based mechanisms to mesotrione and chlorsulfuron with only non-target-site based mechanism of resistance to atrazine leaving fewer options for weed control, especially in no-till crop production systems. Such multiple herbicide resistant Palmer amaranth populations are a serious threat to sustainable weed management because metabolism-based resistance may confer resistance to other herbicides and even those that are yet to be discovered. The findings of this research are novel and valuable to recommend appropriate weed management strategies in the region and should include diversified tactics to prevent evolution and spread of multiple herbicide resistance in Palmer amaranth.

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