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1
Al-Allagi, Musa. "Integrated weed management in spring cereals : the contribution of crop genotype and seed quality." Thesis, University of Reading, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.553091.
Повний текст джерелаАнотація:
Research was conducted at Reading University over three growing seasons into alternatives to herbicides m spnng cereals by identifying traits that enhance crop competitive ability and exammmg the role of seed quality in Integrated Weed Management (IWM~. Nine spring wheat genotypes, spring Barley, spring Triticale and a mixture of spring wheat genotypes Paragon and Belvoir were monitored for their competitive ability in three weed treatments, i.e. weed free and with model weeds Sinapis alba L. or Avena sativa L. The ranking of competitive ability (CA) was estimated from both crop tolerances to weed pressure (i.e. a low crop grain yield loss - CYL) and weed suppression. Genotypic differences in CA were repeatable, with CYL of 28%, 39% and 28-75% for barley, triticale and wheat in 2003, respectively. Barley also suppressed weed biomass by 59% more than wheat. Among wheats, Axona consistently maintained higher yields (10% CYL in 2002 and 46% in 2003). Paragon suppressed weeds by 63% in 2002 and 50% in 2003 whereas cv. Status was a poor competitor. The wheat mixture reduced CYL but had no significant effect on weed suppression. An important observation for variety trials was that the ranking for grain yields in weed free plots was inconsistent with those with weeds. Competitive genotypes tended to be taller and have rapid early growth at GS 15 giving early ground cover, a higher absolute growth rate at GSI5, a shorter mean time to emergence and higher early leave area. On seed quality and its interactions with agronomic practices such as seeding rate and sowing date, doubling seed rate improved crop competitiveness if the crop was sown at the same time as weeds rather than a week later. When a vigorous seed lot was used, higher number of seedlings, ground cover, harvest index and number of fertile tillers per m2 and lower mean time to emergence contributed to its higher crop grain yield. High vigour seeds suppressed total weed biomass up to 89,-43 and 63% in three experiments, the suppression varying between individual weed species. For example, when natural weed infestations were present, high vigour seeds suppressed Convolvulus arvensis L. by 52.5% and Solanum nigrum L. by 95.5%. One particular feature of this thesis was an attempt to understand why high vigour seeds are more competitive. The results indicated that more than 75% of the variations in grain yield and 81 % of the variation in weed dry mutter suppression can be accounted for due to achieving more rapid emergence than the weeds.
2
Ali, Niaz. "Molecular markers, cytogenetics and epigenetics to characterize wheat-Thinopyrum hybrid lines conferring wheat streak mosaic virus resistance." Thesis, University of Leicester, 2012. http://hdl.handle.net/2381/10951.
Повний текст джерелаАнотація:
Genetic resistance to Wheat streak mosaic virus (WSMV) offers the most attractive and environmentally safe strategy for disease control. While effective resistance in hexaploid bread wheat (Triticum aestivum) has recently been described in only one case, the Wsm2 gene, more successful resistance has been introgressed from the related hexaploid wheatgrass, Thinopyrum intermedium, as the Wsm1 and Wsm3 genes. In the current study, fluorescent in situ hybridization (FISH) with genomic DNA from Th. intermedium, Aegilops tauschii and repetitive DNA probes was applied to four breeding populations of wheat-Th. intermedium, previously tested for WSMV-resistance. Three different wheat-Th. intermedium recombinant chromosomes, the well-known 4Ai#2S.4DL and two novel, 1B and 3D, were identified to be associated with WSMV-resistance. These novel introgressed genes from Th. intermedium were designated as Wsm4 and Wsm5 respectively. The Wsm4 gene was pinpointed to a 6% interstitial map region on the 1BS flanked by Xgwm4144 and Xgwm1100 markers. Six new PCRmarkers, five linked to Wsm1 and one to Wsm4 were identified. Molecular markers now provide a good coverage of the 4Ai#2S arm for effective marker assisted selection and the new genes increase our arsenal to combat the disease. Two highly repetitive satellite DNA families, Afa and pSc119.2, were isolated for the first time from Th. intermedium and their diversity in respect to copies from other Triticeae species were investigated. They showed contrasting evolutionary dynamics leading to time dependent or independent homogenization of Afa and pSc119.2 sequences. Both repeats are excellent cytological markers and characterized the 4Ai#2S chromosomal arm, in the alien wheat lines and the Th. intermedium genome. Southern hybridization, with methylation sensitive and insensitive restriction enzymes and immunostaining with anti-5-methyl-cytosine antibodies were employed to assess DNA methylation. Overall, no massive changes were evident in the wheat genome, however the alien arm showed reduced cytosine methylation which is characteristic for actively transcribing chromatin.
3
Davey, Jeffrey Stewart. "Intraguild predation among generalist predators in winter wheat." Thesis, Cardiff University, 2010. http://orca.cf.ac.uk/55042/.
Повний текст джерелаАнотація:
Modern annual arable crops are susceptible to outbreaks of pests due mainly to the uniform habitats that agricultural fields represent. Cereals are particularly prone to infestations of aphids, which may damage the crop directly through herbivory, or indirectly by acting as vectors of disease. These insects, however, have a large range of invertebrate natural enemies, which under certain circumstances, can maintain infestations below economically damaging levels. Greater habitat complexity at landscape and farm scale usually leads to more diverse assemblages of natural enemies at the field scale, but such diversity less often translates to a higher risk for pests. When higher natural enemy diversity is associated with lower levels of pest control, intraguild predation (IGP) is often cited as one of the primary antagonsitic mechanisms. IGP occurs where predators not only compete for the same resource, but also partake in a trophic interaction with one another. Controlled experiments suggest that the niche proximity of predators relative to each other and their shared prey may help predict the outcome of multiple- predator interactions. The primary aim of this thesis was to assess levels of IGP amongst generalist invertebrate predators and to elucidate their spatial patterns, in fields of winter wheat (
4
Almuayrifi, Mohammed Saleh B. "Effect of fertilisation, crop protection, pre-crop and variety choice on yield of phenols content diseases severity and yield of winter wheat." Thesis, University of Newcastle upon Tyne, 2013. http://hdl.handle.net/10443/2196.
Повний текст джерелаАнотація:
There is increasing pressure from government legislation and supermarket quality assurance schemes to reduce chemosynthetic pesticide-inputs in conventional production systems. This has resulted in the need to study potential management based approaches to develop alternative management (e.g. rotational design or crop nutrition) strategies and/or crop breeding/variety selection based approaches to reduce disease pressure or crop resistance to biotic stress. Two long-term, factorial field trials (the NSCS and the NUE-crops trials) were used to assess effects of fertiliser input types (composted manure vs mineral fertilisers), fertiliser input levels, pre-crop/rotational position, crop protection (with and without the use of chemosynthetic pesticides) and wheat genetics/variety choice on phenolic profiles in flag leaves, foliar disease severity and grain yield in winter wheat. Interactions between crop management practices and growing season were investigated using univariate and redundancy analysis approaches. Flag leaf concentrations of phenolic compounds differed between years and plant growth stages and were higher (approx 40%) in crops fertilised with organic compared to mineral fertilisers, but there were virtually no effects of crop protection on phenolic profiles. In contrast, both disease severity and crop yield were significantly affected by crop protection and fertilisation practices. The use of conventional, pesticide based crop protection resulted in lower disease severity and higher yields and mineral NPK fertilisers resulted in lower Septoria and higher mildew and stripe rust severity. Effects of precrop/rotational position and wheat genetics/variety choice, and interactions between precrop, fertilisation, crop protection and/or variety choice were also detected for phenolic profiles, disease severity and grain yield. RDA identified (a) positive associations between organic fertilisation and radiation, and concentrations of phenolic compounds in leaves, (b) positive associations between organic crop protection and relative humidity, and disease severity and (c) negative associations between concentrations of most phenolic compounds and disease severity. Results indicate that it is possible to increaseing concentrations of phenolic compounds in cereals via changes to fertilisation practices, and that this may (a) reduce disease severity and/or increase crop yield in cropping systems which omit chemosynthetic pesticides, but (b) may have no effect on disease and reduced crop yields in cereal cropping systems which use pesticides. However, varietal differences in leaf phenolic expression under organic fertilisation could not be linked to differences in disease severity and yields.
5
Aada, Abdallah. "Identification of pathogens and control of spot blotch disease of barley (Hordeum vulgare) by combining plant resistance and biological control." Thesis, University of Newcastle upon Tyne, 2013. http://hdl.handle.net/10443/2148.
Повний текст джерелаАнотація:
Spot blotch is one of the most important diseases of barley (Hordeum vulgare) in Libya and worldwide. The overall aim of this study was to investigate the potential of biological control in combination with disease resistance to control spot blotch without the potential hazards of chemical application. Fungi were isolated from barley plants with spot blotch symptoms from different areas in Libya. As well as the commonly known spot blotch pathogen Bipolaris sorokiniana (teleomorph Cochliobolus sativus), Bipolaris spicifera (teleomorph Cochliobolus spicifer), Curvularia inaequalis, and Alternaria alternata were identified by their morphology and ribosomal DNA sequences. Bipolaris sorokiniana was the most serious pathogen under the test conditions; the others infected barley but caused less severe symptoms. Spot blotch resistance of barley seedlings was tested under greenhouse conditions with four Libyan cultivars (ACSAD, Nibola, Rehan, and Wadi Utbah) and two UK cultivars (Gaelic and Pastoral). Nibola was the most resistant. The ability of the organisms in three commercial biocontrol products, Trichoderma harzianum T-22 (Trianum), Streptomyces lydicus WYEC 108 (Actinovate) and Bacillus subtilis QST 713 (Serenade), to control spot blotch individually and in combination was investigated. On agar plates, all three inhibited growth of the pathogens completely on the second day of culture, except that for B. spicifera with S. lydicus there was an inhibition zone and the pathogen grew in the opposite direction. Disease severity was lowest when T. harzianum T-22 was applied individually to the most resistant cultivar, Nibola. Foliar application, soil treatment and seed coating all reduced disease severity. With foliar application, T. harzianum T-22 was more effective when applied at the same time as the pathogen than when applied one week before or four days after. In a field experiment with T. harzianum T-22, foliar application combined with seed treatment suppressed spot blotch more effectively than either method individually.
6
Rösti, Sandrine. "The evolution of the cytosolic pathway of ADP-glucose synthesis in cereal endosperm." Thesis, University of East Anglia, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429826.
Повний текст джерела
7
Franke, Angelinus Cornelius. "Ecological and sociological aspects of the Phalaris minor epidemic in the rice-wheat system of Haryana, India." Thesis, University of Glasgow, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433580.
Повний текст джерела
8
Saeed, K. F. "Effect of sulphur and silicon fertilizers on disease control and yield and quality of wheat." Thesis, University of Reading, 2016. http://centaur.reading.ac.uk/69068/.
Повний текст джерелаАнотація:
Published research showed there was a link between the abundance of septoria diseases (Zymoseptoria tritici and Parastagonospora nodorum) and sulphurous acid in acid rain. Historical records showed that P. nodorum was at a peak in 1970s while Z. tritici became more abundant at 1980s. Another, small scale, study showed that both pathogens were affected by sulphur, but Z. tritici was reduced more by sulphur than P. nodorum. These studies suggested it could be useful to investigate the effect of sulphur fertilizer under larger scale, field, conditions. Thus, the aim of this project was to study if sulphur fertilizer affects the abundance of these pathogens, and to study if sulphur fertilization alters the yield and quality of wheat under disease pressure. A further question was whether silicon fertilizer affects both pathogens and the yield and quality of wheat. A final aspect of this thesis was to develop a way to quantify pathogens by using qPCR assay on large field samples. A glasshouse experiment showed that all wheat cultivars were susceptible to available pure isolates of both pathogens, but the proportion of leaves infected by these isolates varied between cultivars. Cv. Paragon showed a high proportion of infected leaves in comparison with Gallant and Maris Huntsman (M. Huntsman). Three successive field experiments were conducted. Z. tritici infected all plots, so it was not possible to estimate changes in competitive effects due to the fertiliser regimes. In the field experiments a variety of measurements were used at different growth stages to assess the diseases. The proportion of leaves infected with, and disease severity of, Z. tritici were not significantly affectedly by sulphur fertilization in 2013. In two further experiments, proportion of leaves infected with, and spore concentration of, Z. tritici were reduced by sulphur fertilization. In the 2014-2015 experiment disease severity of Z. tritici was significantly reduced by sulphur fertilization. Although autumn spray and seed inoculation with P. nodorum did not succeed, a spring spray inoculation was successful in the 2014-2015 experiment. In this experiment, proportion of leaves infected and disease severity of both fungi were reduced by sulphur fertilization. but Z. tritici was reduced more than P. nodorum. These results agree with the historical trends. Yield and quality measurements results showed that sulphur fertilization increased yield and the wheat quality was improved. This result was obtained when the sulphur fertilization was split and applied at multiple times throughout the growing season of wheat (Table 6).
9
Chuong, Nguyen Duc Xuan. "Identification of radiation use efficiency traits in a wheat and spelt population." Thesis, University of Nottingham, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.662207.
Повний текст джерелаАнотація:
Wheat is one of the main staple food crops, providing an essential source of carbohydrates for millions of people. Therefore, demand for wheat will increase in next few decades as the global population increases toward a prediction 9 billion by 2050. Further advances in wheat yield requires the integration of new tools and strategies to complement traditional approaches to select genotypes that are better suited to abiotic stress, in the context of climate change. Identifying morphological and physiological characters, correlated with tolerance to environmental stress, is a priority for wheat breeders. One approach that can be combined in wheat breeding programmes is to create new genetic variation, for example by crossing wheat with close relatives such as spelt. The overall objective of this study is to investigate the physiological traits associated with radiation use efficiency (RUE) in a segregating population of 225 recombinant inbred lines, originating from the cross of wheat (cv. Forno) with spelt (cv. Oberkulmer). Three field experiments from 2010 to 2012 were carried out at Sutton Bonington. All lines, and their parents, were grown as ear rows in 2010 and arranged in randomized design with one replicate of mini plots in 2011. In 2012 three replicates were grown in a randomised complete block design. In these experiments, plant development, RUE, biomass, grain yield and associated physiological traits were measured in the recombinant inbred lines. In addition, a glasshouse experiment was conducted in 2013 to investigate gas exchange traits amongst 18 selected lines with a wide range of RUE, alongside the parents.
10
Xia, Jing. "Immunocytochemical localisation of arabinoxylans in the wheat (Triticum aestivum) caryopsis using a polyclonal antibody." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396093.
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11
Gould, Nicholas. "The role of phloem in K'+ nutrition of barley (Hordeum Vulgare L.)." Thesis, University of Birmingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395733.
Повний текст джерела
12
Badaruddin, Muhammad. "Investigating the role of glycogen metabolism in the rice blast fungus Magnaporthe oryzae." Thesis, University of Exeter, 2011. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548630.
Повний текст джерела
13
Hands, Philip Stuart. "Comparative grain development in temperate grasses." Thesis, University of Leicester, 2013. http://hdl.handle.net/2381/27807.
Повний текст джерелаАнотація:
Temperate or pooid cereal crops, such as wheat, barley and oat, represent a major world food source much of which is attributable to the storage capabilities of the cereal endosperm and influences of domestication selection. Brachypodium distachyon has recently become established as a genome-sequenced model system and the first wild member of the Pooideae be studied in detail. We provide the first detailed description of grain development in Brachypodium assessing its suitability as a model for grain development in crop species. Cellular and molecular mapping of developing Brachypodium endosperm domains reveals significant differences in aleurone differentiation reflecting differences in grain filling and endosperm storage reserves. We extend this survey of grain morphology and endosperm organisation to a wider sample of the Pooideae incorporating both wild and cultivated species. Focusing on the functionally important aleurone domains, distinct patterns of grain tissue organisation are described. Results indicate that organizational features are correlated to species’ ecological and grain quality characters and that the modified aleurone region, absent in Brachypodium, may be a feature of only a subset of cereals, specifically the Triticeae tribe. A more systematic candidate gene approach focusing on transcription factors was initiated in attempts to find the genes underpinning this variation. The identification of orthologous key regulatory genes with both similar and contrasting patterns of expression provides information on the differences and conservation of grain developmental pathways amongst the Pooideae. To investigate function of candidate genes, publically available insertional mutants for major MADS-box and YABBY genes were obtained and characterized, while simultaneously attempting to establish genetic transformation protocols to enable RNAi analyses of other candidate genes.
14
Khan, Thana Khalid. "Transcriptional and physiological responses of wheat Triticum aestivum to a combination of abiotic and biotic stress." Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/3511.
Повний текст джерелаАнотація:
Plant responses to simultaneous biotic and abiotic stresses involve the activation of multiple signalling pathways that often interact in a synergistic or an antagonistic manner. Recent studies have shown that the plant response to a combination of stresses differ to those that occur when exposed to a single stress. The aim of the present study is to investigate the response of wheat (Triticum aestivum) to both salinity and aphid Sitobion avenae infestation, applied singly and in combination, at the physiological and transcriptional levels, to provide a better understanding of the impact of abiotic and biotic interactions and cross tolerance in wheat. These two forms of stress were selected since they are known to have a major impact on crop productivity. Wheat genotype 122-1 was shown to be tolerant to salt (160 mM NaCl) on the basis of biomass; accumulating high levels of Na+ in the shoots and was partially resistant to aphids in terms of fecundity. Pretreatment of this genotype with salt significantly (p < 0.001) reduced aphid fecundity (by 37%) relative to its control, indicating enhanced resistance to aphids. This positive interaction between salt and aphid stress was investigated at 6h and 24h post aphid infestation on the wheat transcriptome. Microarray analysis indicated common and specific gene expression patterns of the 61.290 transcripts differentially regulated in response to salt stress alone, aphid infestation alone and dual stress compared to the controls. Dual stress specifically and strongly increased the transcription level of the following genes assigned to jasmonate synthesis encoding lipoxygenase (LOX), abiotic stress (heat), miscellaneous enzyme families (acid and other phosphatases) at 6h, and secondary metabolism (phenylpropanoids) at 24h. Furthermore, based on functional classification analysis, several categories which were shown to be significantly activated by dual stress such as cytokinin hormone synthesis and MAP kinases signalling were not, however, significantly changed under either salt stress or aphid infestation alone. The current study demonstrated that jasmonate hormone signalling pathways antagonized those of salicylic acid under dual stress and aphid infestation at 6 h. Results suggests that the interaction between combined salinity and aphids stresses caused distinct alteration in gene expression patterns that could not be detected under either of the two stresses when applied individually. This study proposes that the activation of specific genes involved in the acquisition of defence/tolerance, such as those encoding cytochrome P450 and MYB domain transcription factor families, due to prior exposure to salt may enhance subsequent tolerance to aphids. The present study sheds light on candidate genes with putative functions in the crosstalk and the acquisition of cross tolerance and provides new insights on wheat response to multiple stress conditions. Such information is a prerequisite for enhancing crop tolerance to a broad-spectrum of stress.
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Gamble, Mary. "Molecular characterisation of the Rhynchosporium commune interaction with barley." Thesis, University of Dundee, 2016. https://discovery.dundee.ac.uk/en/studentTheses/cf6bac20-95db-47bb-b0dc-566eac626641.
Повний текст джерелаАнотація:
The molecular interaction between Rhynchosporium commune and its host barley was studied to gain a better understanding of the pathogen during infection and provide further characterisation of resistance in barley, using a combination of bioinformatics, transcript expression analysis, proteomics and confocal microscopy. Expression analysis of potential effector sequences identified novel candidate effectors Rc_10934, Rc_2091 and Rc_2835 which showed the highest abundance during the biotrophic infection. A further two novel candidates Rc07_03591 and Rc07_02334 and a LysM containing protein (RcLysM3) were identified using a proteomic analysis of infected plant apoplast. Further apoplastic analysis revealed some of the most abundant proteins that are present in R. commune’s infection toolkit. Cell wall degrading enzymes (CWDEs), virulence factors and proteins involved in detoxification were all highlighted as some of the main key players of pathogenesis. A large family of LysM domain containing proteins was later identified in the R. commune genome. Expression profiling revealed the upregulation of some of the transcripts during infection, indicating a potential role in pathogenesis, whereas others were expressed in vitro indicating potential functions for the proteins in fungal growth and development. RcLysM3 containing 3 LysM domains and sharing similarities with the well-known C. fulvum Ecp6 effector was selected for further characterisation. Bioinformatics predictions showed a high affinity for chitin binding which was confirmed in vitro. Binding analysis revealed that it can also bind chitosan but not plant cell wall polysaccharides, indicating that it is potentially involved in the evasion of plant immune responses. The presence of the effector was also identified in the apoplast of infected barley leaves using a proteomic approach. R. commune strain expressing GFP was used to characterise differences in pathogen growth and colony morphology in response to different genetic backgrounds of barley using lines carrying the Rrs3 (Abyssinian), Rrs4 (CI11549) and Rrs13 (BC line 30) genes and barley landraces with uncharacterised resistance. Rrs1 resistance was further analysed using comparative proteomics to identify proteins differentially expressed in resistant and susceptible cultivars. Pathogenesis related proteins - chitinase, glucanase and thaumatin-like protease, were identified in the barley apoplastic fluid and were shown to be upregulated during infection. In addition, serine carboxypeptidase and purple acid phosphatase proteins were identified that were novel to the barley resistance interaction but have been identified in other incompatible interactions as defence related proteins. The final chapter of this thesis is dedicated to the analysis of asymptomatic growth of R. commune on the model dicotyledonous plant N. benthamiana and analysis of effector transcription during growth on a non-host. R. commune growth was shown to be confined to the leaf surface, with no evidence of plant cell deterioration in transgenic N. benthamiana plants expressing an mRFP-tagged plasma membrane protein. This system could be used for further research into non-host interactions and provides insights into the growth of R. commune on alternative plant species.
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Lewis, Rebecca Sian. "Charcterising mismatch repair in wheat (triticum aestivum)." Thesis, University of Bristol, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.681489.
Повний текст джерелаАнотація:
To meet the nutritional requirements of a growing population, world agricultural output must increase by 70-100% by 2050. However, worldwide wheat yields are close to reaching a 'glass ceiling'. In order to meet the challenges of a rapidly growing population, scarcity of resources and a trend toward high-protein diets, traditional agriculture has looked towards molecular biology for insight and innovation for the future. Studying the mechanisms underlying DNA damage and repair is crucially important to facilitating generation of novel variation and developing breeding techniques. The Mismatch Repair (MMR) system is a highly-conserved series of pathways responsible for maintaining genomic integrity in prokaryotes and eukaryotes. The constituent proteins repair DNA mismatches and prevent meiotic recombination between homoeologous sequences. Work in Arabidopsis, tobacco and tomato has shown that plants with an impaired MMR system accumulate point mutations and undergo increased homoeologous recombination, which may be useful in breeding programs. Two key MMR genes are explored: MutS Homologue 2 (MSH2) acts as a heterodimer with MSH3, MSH6 or MSH7 to detect point mutations, insertions and deletions. Post Meiotic Segregation increased 2 (PMS2) is a homologue of the MutL gene, which co-ordinates repair of mismatches. The two genes were cloned and sequenced from elite cultivar Cadenza, and the sequences subsequently compared to next generation sequencing data from Chinese Spring. Three homoeologous copies of each gene were identified in the genome of wheat, and two of these were sequenced from the transcriptome. The expression of MSH2 was studied using qPCR in the transcriptome of Cadenza and four gamma-irradiated deletion lines, generated in a Paragon background. The four deletion lines showed varying responses: from down-regulation of MSH2 expression by 57% to upregulation by 82%. The expression of the individual homoeologues of MSH2 were also explored using a qPCR based method and by examining RNAseq data, but this was inconclusive.
17
Tejakhod, S. "The effect of simulated flooding post-anthesis on pre-harvest sprouting and subsequent seed longevity in contrasting rice cultivars." Thesis, University of Reading, 2016. http://centaur.reading.ac.uk/63179/.
Повний текст джерелаАнотація:
Unpredictable flooding is a major constraint to rice production. It can occur at any growth stage. The effect of simulated flooding post-anthesis on yield and subsequent seed quality of pot-grown rice (Oryza sativa L.) plants was investigated in glasshouses and controlled-environment growth cabinets. Submergence post-anthesis (9-40 DAA) for 3 or 5 days reduced seed weight of japonica rice cv. Gleva, with considerable pre-harvest sprouting (up to 53%). The latter was greater the later in seed development and maturation that flooding occurred. Sprouted seed had poor ability to survive desiccation or germinate normally upon rehydration, whereas the effects of flooding on the subsequent air-dry seed storage longevity (p50) of the non-sprouted seed fraction was negligible. The indica rice cvs IR64 and IR64Sub1 (introgression of submergence tolerance gene Submergence1A-1) were both far more tolerant to flooding post-anthesis than cv. Gleva: four days’ submergence of these two near-isogenic cultivars at 10-40 DAA resulted less than 1% sprouted seeds. The presence of the Sub1A-1 allele in cv. IR64Sub1 was verified by gel electrophoresis and DNA sequencing. It had no harmful effect on loss in seed viability during storage compared with IR64 in both control and flooded environments. Moreover, the germinability and changes in dormancy during seed development and maturation were very similar to IR64. The efficiency of using chemical spray to increase seed dormancy was investigated in the pre-harvest sprouting susceptible rice cv. Gleva. Foliar application of molybdenum at 100 mg L-1 reduced sprouted seeds by 15-21% following 4 days’ submergence at 20-30 DAA. Analyses confirmed that the treatment did result in molybdenum uptake by the plants, and also tended to increase seed abscisic acid concentration. The latter was reduced by submergence and declined exponentially during grain ripening. The selection of submergence-tolerant varieties was more successful than application of molybdenum in reducing pre-harvest sprouting.
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Wamaedeesa, Raheema. "Molecular aspects of 2OG-Fe(II)-dioxygenases and response to abiotic stress in rice." Thesis, University of Reading, 2016. http://centaur.reading.ac.uk/68587/.
Повний текст джерелаАнотація:
In specific mammalian cells, the Ten-Eleven Translocation (TET) enzymes which are family members of 2-oxoglutarate (2-OG)-and Fe (II)-dependent dioxygenase (2ODD) are responsible for the modification of 5-mC to generate oxidised products such as 5-hmC, 5-caC and 5-fC, which are involved in oxidative demethylation. In rice, some reports have also revealed that 5-hmC was also present but the enzyme(s) responsible for oxidising 5-mC has not been identified. Here, possible Tet gene homologues in rice were identified by using various databases. There are 18 genes having a 2ODD domain most similar to TETs. Moreover, additional significant information such as the relatedness of protein sequence, protein interaction, nuclear localisation prediction, mutant analysis as well as gene annotation was obtained. Next, the spatial and temporal expression patterns of these genes were analysed within seedling root, mature leaf, young leaf and young panicle by analysing data from both microarray and qPCR. It was found that Os01g0546900 had highest expression in young leaf and six genes showed highest expression in mature leaf, whereas the remaining genes showed low expression in various organs. Finally, selected contrasting cultivars of rice were used to examine the expression of three genes of 2ODD and SLENDER RICE 1 (SLR1) under flooding and drought in order to evaluate the molecular aspects of Submergence 1A (Sub1A) regulation. The results showed that the Sub1A gene of tolerant rice was highly expressed under submergence but was not expressed under drought. Os03g0803500, Os07g0194500 and Os09g0489200, and SLR1 did not show any significant difference in expression in submerged and dehydrated plants of both IR64 and IR64.S1, nor in Japonica varieties which were used as susceptible check. To conclude, this finding indicates that Os03g0803500, Os07g0194500, Os09g0489200 and SLR1 may not have a correlation with Sub1A under flooding and drought stress.
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Steinmeyer, Frederick Thomas. "Spike temperature depression of wheat (Triticum aestivum L.) at anthesis." Thesis, University of Reading, 2016. http://centaur.reading.ac.uk/68662/.
Повний текст джерелаАнотація:
Global climate change has been forecast to result in significant alterations to current temperature and precipitation patterns in cereal growing regions worldwide. The increased occurrence of elevated temperature stress at anthesis is likely to result in significant yield losses in wheat (Triticum aestivum L.). The ability of plant tissue to depress its temperature has been reported in relation to the canopy but recent work has demonstrated that spike temperature depression (STD) can be assessed in controlled environments (CE). The findings from two consecutive years of potbased CE experiments, a field-based experiment under polytunnel cover and a rhizobox-based experiment, in which the thermal dynamics of the spike and flag leaf under contrasting conditions of elevated temperature and water-deficit stress at anthesis, are reported. Flag leaf temperature depression (FLTD) was significantly greater than STD at anthesis. The data do not demonstrate an increased cooling capacity of the spike in the early stages of anthesis but rather in the latter stages, a phenomenon hypothesized to be primarily associated with the onset of senescence in the canopy. The inconsistent relationship observed between FLTD/STD at anthesis and grain yield (GY) does not currently elucidate whether a failure to depress tissue temperature at anthesis is associated with a yield penalty. The effect of experimental design on the physiological response to abiotic stress at anthesis was explored. The plant-wide distribution of photoassimilates at mid-anthesis was examined. Starch and water-soluble carbohydrate content in the flag leaf, peduncle and glumes was not found to correlate to GY. Further examination of the effects that abiotic stress at anthesis have on the photoassimilate distribution and GY need to take place in field-grown wheat.
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Illes, Mary. "Role of nitric oxide and nitric oxide synthases in the rice blast fungus." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670065.
Повний текст джерела
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Goodwin, Hazel Emma. "The evolution and spread of Triticum aestivum L. in Europe." Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702440.
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Judge, Christopher. "Disease escape in relation to a trade off between Septoria tritici blotch and yield of wheat." Thesis, University of East Anglia, 2015. https://ueaeprints.uea.ac.uk/59397/.
Повний текст джерелаАнотація:
Zymoseptoria tritici, the fungus that causes Septoria tritici blotch (STB) of wheat, is spread by splash borne transfer from the base of the plant to the flag leaf. This project is on a potential new source of resistance to STB discovered on chromosome 6A using association mapping (Arraiano & Brown 2016). Near isogenic lines generated for this region show no significant differences in STB symptoms when leaves are directly inoculated with Z. tritici. However, trials that are naturally infected or inoculated at the base of the plant show clear differences in their level of STB. This indicated that this region contains genes that cause differences in disease escape. The fact that the same marker Psp3071 is associated with yield traits (Snape et al, 2007) led to the hypothesis that the region may control a physiological trait that improves yield at the cost of aiding spore transmission. Candidate physiological traits, that could influence disease escape, have been tested in the 6A NILs including plant height, leaf area and senescence. The trait that fits with the pattern of the disease results best is leaf emergence, with later emerging leaves getting more STB. However, the effect of the 6A alleles on disease escape may be caused by multiple traits. Recombinant lines generated for the region have reduced the interval that contains the yield traits, though it is still unclear if the disease escape and yield effects are connected by linkage or pleiotropy.
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Barral, Baron Guillaume. "Investigation and validation of QTL for yield and yield components in winter barley." Thesis, University of Newcastle upon Tyne, 2016. http://hdl.handle.net/10443/3329.
Повний текст джерелаАнотація:
The rapid development of biotechnologies in crop genetics has increased the prospects for more efficient crop improvement. In barley breeding programmes, marker assisted selection (MAS) approaches for quantitative trait loci (QTL) for yield and yield components is still developing as it requires a thorough understanding of the genetic architecture of complex traits. This project reports an investigation of QTL for yield and yield components in two-row winter barley using three QTL mapping experiments. First, a bi-parental mapping population from an elite cross identified 23 genetic factors involved in the control of complex traits, including a strong grain weight QTL on the short arm of chromosome 2H. Second, two genome wide association studies (GWAS) were used to explore the genetic diversity for agronomic traits in European variety panels used in the NUE-CROPS and the AGOUEB projects. The integration of QTL mapping results revealed clustering of significant effects as potential targets for MAS. A major QTL cluster identified on 2H suggests that the centromeric HvCEN candidate gene is strongly involved in controlling the phenology and number of grains per ear in two-row winter barley and has additional pleiotropic effects on several agronomic traits. Some QTL effects were further confirmed by a QTL validation experiment using near isogenic lines (NILs) developed from advanced breeding material alongside the mapping experiments. Most of the QTL clusters involving different yield components showed that allele effects mirrored phenotypic correlations and a few QTL clusters were identified that had unidirectional increasing effects on all traits, such as an important tillering locus on 4HL. The exploitation of comparative genomics with rice revealed that SNP haplotypes could be used for candidate gene discovery at barley QTL clusters. The complexity of the QTL clusters associated with yield and yield components highlight the challenges in identifying relevant targets for marker assisted breeding when accounting for pleiotropic effects of loci controlling phenology and correlated traits. The study provides insights into the genetic architecture of complex traits in small grain cereals and for the implementation of associated QTL in commercial barley breeding activities.
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Ramirez, Gonzalez Ricardo. "Next generation genomics tools for wheat improvement." Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/63098/.
Повний текст джерелаАнотація:
In recent years the amount of genomic resources of wheat has increased to the point where manual analysis is unfeasible. The aim of this PhD was to develop bioinformatics tools that help answer biological questions relevant to research and breeding by addressing the complexities associated with the wheat genome. I took advantage of resources which became publicly available as the analyses were carried out and I developed new approaches, strategies and tools to help accelerate wheat research. Chapter 1 reviews the genomic resources used for the thesis, placing them in historic context with the work and analyses performed. Chapter 2 describes the development of PolyMarker, a bioinformatics pipeline to design genome-specific primers in a timely and effective manner. Examples of different applications of PolyMarker are also included. Chapter 3 describes the analysis of an F2 population to generate a genetic map for Yr15, a gene that provides resistance to yellow rust. The SNP calling was done from bulked segregating samples, sequenced with RNASeq as a method of reduced representation. Chapter 4 describes expVIP, a tool to integrate RNA-Seq experiments in a relational database. Data from different studies can be visualised simultaneously, enabling comparisons between them. Lastly, in Chapter 5 all the data types used for the analysis on each of the previous chapters is integrated into a relational database. The discussion further explores how genetic maps, SNP markers, novel SNPs, gene annotations, gene assemblies and gene expression can be used simultaneously in research and breeding programs. All the tools and pipelines described in this thesis are open source and are available on: https://github.com/homonecloco.
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Gonzalez, Navarro Oscar. "Understanding the developmental basis of grain yield potential in bread wheat." Thesis, University of East Anglia, 2017. https://ueaeprints.uea.ac.uk/63110/.
Повний текст джерелаАнотація:
Grain yield potential in wheat is a complex trait controlled by sub-traits like grain number, grain size, and assimilate partitioning. To achieve further understanding of grain yield potential, this thesis combines physiological and genetic dissection of wheat development. In particular, how the length of developmental phases can be optimized in favour of increased partitioning of assimilates to the spike, in order to reduce abortion rates of florets. The physiological section of the thesis (Chapter 2 and 3) comprises the in depth study of the CIMCOG panel (CIMMYT Core Germplasm). In this section the variation in patterns of floret and phenological development was determined, ascertaining how these differences affect the number of fertile florets. The differences in floret development were clear in the intermediate florets (floret primordia 3, 4, and 5 from the rachis). Floret survival was found to be positively related to the length of the period of floret development. Also fruiting efficiency, using the frontier concept, show a positive relationship with the stem elongation period. The genetic section (Chapter 4 and 5) involves the use of quantitative trait locus (QTL) analysis with a segregating population to determine the chromosomal locations affecting key developmental traits. A Buster x Charger doubled haploid population provided a crucial contrast between similar genetic background and differences in length of phenological phases. The results show that a QTL on chromosome 7A has an effect on the time to terminal spikelet phase, i.e. the onset of stem elongation, and QTL affecting time to heading was found on chromosomes 2D and 4A. Furthermore, this population also varies in lodging resistance. A major QTL was found on chromosome 2D affecting height and providing lodging resistance. These studies provide the basis to optimise wheat developmental patterns and, therefore, maximize spike fertility.
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Mark, P. J. L. "A multifaceted evaluation of the effects of heat stress on the pollen development of wheat." Thesis, University of Reading, 2016. http://centaur.reading.ac.uk/66336/.
Повний текст джерелаАнотація:
Pollen formation is considered ‘the Achilles tendon of reproductive development’. Therefore, special attention must be directed towards making sure that pollen is sufficiently robust, in order to cope with future climatic changes. One such anticipated future change in climate is increasing global temperature. Wheat is a very important crop for global food security, but wheat pollen development has been shown particularly sensitive to temperature stress. Therefore, work is needed to increase the environmental resilience of wheat pollen. In this thesis, attempts were made to not only find modern wheat varieties that had an increased tolerance to heat stress during pollen development, but also to clarify which stage(s) of wheat pollen development were the most sensitive to heat stress. Additionally, experimentation was conducted in order to assess the effect of heat stress on anther/pollen related gene expression, and the effect that inter-ear viable pollen movement had on yield restoration. In spite of it being shown that there were varieties that sustained significantly less grain losses, due to a heat stress event, and that a reduced level of pollen damage played a key role in this, it was apparent that this was not an example of tolerance, but instead an example of avoidance. Additionally, unlike previous reports, the developmental stage around pollen mother cell meiosis was not found to be the most significantly affected by heat stress, either in relation to grain number or microspore/pollen wellbeing. Instead, this designation was given to the latter stages of pollen wall development. Heat stress, during pollen development, had a profound effect on the expression levels/patterns of six anther/pollen related genes. This research has established a firm platform, in numerous different areas, for the future exploration of possibilities for reducing the effects of abiotic stress on wheat pollen development, and therefore directly increase yield resilience.
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Bin, Nazri Ahmad. "Unravelling zinc homeostatic mechanisms in the crop plant barley." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/403873/.
Повний текст джерелаАнотація:
Zinc (Zn) is an essential micronutrient in plants but becomes toxic when present in excess, with nutritional extremes leading to agricultural yield losses. Homeostatic mechanisms are in place to control cellular Zn levels with transcription factors and membrane transport proteins playing vital roles. In Arabidopsis thaliana, two F-group bZIP transcription factors, bZIP19 and bZIP23, are proposed to sense and respond to Zn deficiency by regulating the expression of particular Zn membrane transporters, ZIPs (ZRT/IRT-like proteins). In this thesis, four unique bzip19 bzip23 knockout mutants with different combinations of T-DNA insertion sites were generated and shown to be hypersensitive to Zn-deficiency. To understand the role of F-group bZIPs in the economically important crop Hordeum vulgare (barley), HvbZIP1, 10, 56, 57, 58, and 61 were cloned and characterized to various extents. HvbZIP56, HvbZIP57, HvbZIP62 but not HvbZIP1 partially rescue the hypersensitive phenotype of the A. thaliana bzip19-4 bzip23-2 mutant. HvbZIP56 was localised to the cytoplasm and nucleus when expressed in A. thaliana and tobacco. Promoter analysis demonstrates that barley ZIP transporters that are up-regulated under Zn deficiency contain cis Zn-deficiency response elements (ZDREs), similarly to A. thaliana. Overall, these results indicate that the mechanisms operating in controlling Zn levels in barley are conserved. Two transporters, AtHMA3 (a P1B-2-type ATPase) and AtMTP1 (a Metal tolerance protein) have been implicated in sequestering Zn in Arabidopsis vacuoles to alleviate Zn toxicity. In this study, only the mtp1 mutant and not the hma3 mutant showed hypersensitivity to high Zn levels. HvHMA3 (a barley P1B-2-ATPase) when expressed in mtp1 rescued this hypersensitivity indicating a role in Zn transport, although this could not be confirmed by expression in S. cerevisiae. This study represents a significant step forward in understanding the mechanisms controlling Zn responses in cereal crops, and will aid in developing strategies for crop improvement.
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Samnakay, Parwez. "An investigation into the chloroplast transformation of wheat, and the use of a cyanobacterial CCM gene for improving photosynthesis in a C3 plant." Thesis, Lancaster University, 2015. http://eprints.lancs.ac.uk/80974/.
Повний текст джерелаАнотація:
Wheat is a major component of the UK diet, and provides approximately 20% of global caloric intake. Wheat is grown on more land area than any other crop, and the continued supply of wheat is essential for global food security. Biotechnology is likely to play an important role in the sustainable increase of wheat yields, and the genetic manipulation of chloroplasts for photosynthetic improvement has many potential advantages over transformation of the nuclear genome. The genetic modification of the chloroplast genome via transformation was first demonstrated in the late 1980’s, and since then, chloroplast transformation of many Dicotyledonous (dicot) plant species such as Nicotiana tabaccum has been routinely performed. In comparison, the transformation of chloroplasts in Monocotyledons (monocot) plant species, which includes all cereal crops, has made far less progress. To date, there has been no reproducible homoplasmic plastid transformation event in the monocots. This study identifies a number of bottlenecks responsible for the prevention of chloroplast transformation in wheat. One such bottleneck is the lack of a suitable explant for plastid transformation, as traditional nuclear transformation targets are absent of metabolically active plastids. This study has developed a robust regeneration protocol for a previously undescribed tissue, termed the primary inflorescence leaf sheath (piLS), which is rich in active chloroplasts. Functional wheat specific chloroplast transformation vectors have been generated, and bombardment studies have been conducted with these on piLS and a second tissue, the immature embryosderived callus. Immature embryo callus (IEC) does not contain active plastids, however contains pro-plastids and is highly embryogenic. To uncover novel ways of increasing photosynthesis in C3 plants, a number of transplastomic tobacco lines expressing the Synechococcus elongatus PCC 7942 ictB gene were generated. Previous studies suggest that ictB may be an inorganic carbon transporter. In a number of transplastomic lines produced in this study, the intercellular carbon concentration (Ci) is significantly increased. This increased Ci did not result in an increased photosynthetic rate, however did cause a number of phenotypic differences, such as smaller plants, wider leaves, and earlier seed pod formation. The results, with regards to chloroplast transformation, and its implications in improving photosynthesis within C3 plants, are discussed in this thesis.
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Pennacchi, João. "Enhancing photosynthetic capacity and energy conversion in wheat." Thesis, Lancaster University, 2017. http://eprints.lancs.ac.uk/86699/.
Повний текст джерелаАнотація:
Wheat is one of the major grain crops worldwide and provides approximately 20% of the total caloric and protein input for the world’s population. An increase in crop yields is required to meet the demands of the increasing world population in a challenging scenario of less predictable climatic conditions and sustainability requirements. There is an urgent need to develop crop plants that are more productive per land area and yield more stable outputs, without having to increase inputs of fertilizer or water. The canopy light-driven carbon uptake through photosynthesis is the primary determinant of plant biomass and yield. In this context, it is crucial to understand crop physiology and plant behaviour, with a focus on carbon balance, in contrasting environments, as well as to map the interactions between traits that drive wheat yields. Exploiting new methods of enhancing yield through successful strategies observed in other organisms can be used to achieve positive results for crop improvement. The impact of contrasting environments in wheat development and yield was studied in a panel of elite wheat cultivars over 3 seasons in UK. Late sowing and lower rainfall decreased the duration of grain development, impacting on grain yields. Yield stability was related to the crop resilience to shorter grain development periods and was partially explained by genetic similarities between cultivars or by the presence of genes related to crop development. The interaction between traits recognized as potential yield drivers and their stability and correlation to yield were studied in a double-haploid wheat mapping population. Traits correlated to light interception and use, and biomass allocation were strong yield drivers. Different lines adopt different strategies, based on these traits, to achieve high yields. The possible effect of the insertion of the ictB gene, related to carbon concentration in the chloroplast in cyanobacteria and to improved yields in plants, was studied in genetically modified wheat plants. No improvement was observed for photosynthetic traits or yield in the transgenic plants when compared to control plants, although unforeseen experimental problems could have hidden the expected phenotype. The achievements of this research contribute to improve the knowledge of wheat yield formation, its correlation to the carbon uptake process and stability in different climatic conditions. It may lead to a better understanding of new potential strategies to be applied in the breeding of genotypes for higher and more stable yields.
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Mirzaei, Heydari Mohammad. "The role of bio-inoculants on phosphorous relations of barley." Thesis, Bangor University, 2013. https://research.bangor.ac.uk/portal/en/theses/the-role-of-bioinoculants-on-phosphorous-relations-of-barley(7fa4da0a-1d19-4df4-95ff-5da3905da1cc).html.
Повний текст джерелаАнотація:
Phosphorus (P) is one of the most limiting and important elements in crop production, yet often has limited availability in the soil. Manufactured inorganic P fertilisers are required to improve soil and crop P supply but their use depletes finite reserves of rock phosphate and impacts on water quality and ecosystem biodiversity. Bio-inoculants have a potential role to increase soil P supply and reduce dependence on expensive fertilisers. The objective of this thesis was to further understand the role of mycorrhizae (M) and P solubilizing bacteria (PSB) bio-inoculants and external P sources (super phosphate (SP), struvite (AMP) and rock phosphate (RP)on phosphorus availability in soil and their effects on the growth, yield and P uptake of barley. Field experiments on low P status soils in 2010 and 2011 demonstrated the potential for the use of bio-inoculants (PSB and M) in mobilizing P from soil and significantly (P <0.05) enhancing P uptake to increase growth of barley, and to a lesser extent, grain yield. It was postulated that bio-inoculant effects in the field were compromised by the presence of native M and PSB. Glasshouse pot experiments were conducted with a range of growth media: horticultural sand (zero P), field soil (low P status but with native micro-organisms) and heat sterilized field soil. These demonstrated the effects of bio-inoculants without the presence of native M and PSB, and to a lesser extent in the presence of native micro-organisms, in terms of increased plant root and shoot growth, grain yield and tissue P concentration. Across all experiments bio-inoculants (M and PSB) increased the effectiveness of water soluble SP, partially soluble AMP and insoluble RP. M and PSB were equally effective. In combination with these external P sources, bio-inoculants (M and PSB) significantly (P < 0.05) increased yield, P concentration and total P uptake, plant dry matter and concentration of P in the grain compared to P fertilizers without bio-inoculants. However, applications of P fertilizers reduced the colonization of roots by mycorrhizae. The potential role of P uptake enhancing bio-inoculants in reducing external inputs in agriculture is discussed.
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Soleimani, Mohammadreza. "The effect of rain and agronomy on seed dormancy and quality of winter cereals." Thesis, University of Reading, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.739381.
Повний текст джерелаАнотація:
Variation in agronomy and crop production environment often have interactive effects on cereal seed dormancy and seed and grain quality, possibly by effects on canopy temperature, seed size, or grain drying rate. The effect of rain, nitrogen (N) fertilizer, and fungicide on seed dormancy, grain quality and subsequent seedling growth of winter cereals was studied in three field experiments. Dormancy was released during seed development and maturation in barley, rye and triticale (2012) but released and then re-imposed in wheat (2012 and 2013). Dormancy release was stimulated in barley, rye and triticale, but not wheat, when crops were sheltered from rain in the field. Alpha-amylase activity was reduced and Hagberg falling number (HFN) increased by rain shelter in barley and wheat; HFN was associated positively with grain drying rate in barley and rye. Dormancy release in wheat was stimulated by fungicide application but delayed by early N. The latter increased sulphur and protein concentrations, HFN, and sodium dodecyl sulphate sedimentation volume. This effect was greater when fungicide and/or late N application were also applied. Fungicide improved subsequent seedling growth in wheat in 2012 only. Plumule and root length and dry weight were associated positively with seed size in both years. It is proposed that rain and N fertilizer delayed dormancy release through an indirect effect on grain drying rate and/or canopy temperature, whereas fungicide stimulated dormancy release by reducing grain surface fungal colonies. As expected, rain reduced but N fertilizer increased HFN, but treatment effects on grain drying rate and/or seed size could not account for all these effects on HFN. Fungicide increased subsequent seedling growth indirectly by increasing seed size in addition to a direct effect of fungicide on reducing infection on seedlings, but only when crop disease pressure was high (2012, not 2013).
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Sapna, Kumari. "Effect of simulated rainfall and drought on wheat seed and grain quality development." Thesis, University of Reading, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.740775.
Повний текст джерелаАнотація:
The effect of drought and simulated rainfall on wheat (Triticum aestivum L.) seed and grain quality during development and maturation, including delayed harvest, were investigated with pot-grown plants harvested serially in a ventilated poly tunnel. Grain quality was assessed by seed mean dry weight (MOW), moisture content, HFN (Hagberg falling number), 50S (sodium dodecyl sulphate sedimentation), nitrogen content, sulphur content a nd seed size; seed quality by ability to germinate and subsequent air-dry seed storage survival. Developmental duration was the dominant factor influencing quality: HFN increased progressively and substantially from early seed filling to beyond harvest maturity in a sigmoidal pattern; 50S in a linear trend in 2012, but plateaued in 2013 from the end of seed filling; seed longevity in a curvi-linear trend (quantified by a polynomial) till harvest maturity; ability to germinate was maximal (100% normal germination) from 15-17 days before to 30-32 days after mass maturity (control). Stopping irrigation before seed filling ended reduced MOW and grain size, but increased HFN, 50S, germinability and seed longevity. Drought resulted in more rapid increase in HFN (14 days after anthesis > 21 DAA > 28 DAA > Control) and earlier attainment of maximum seed longevity. Ear wetting once close to harvest maturity reduced HFN considerably; thereafter it increased, though less than the control. Ear wetting reduced but root wetting increased HFN early in development, whereas both treatments at harvest maturity reduced seed and grain quality. Ear wetting reduced subsequent seed longevity immediately, but a period of re-drying in planta improved longevity - surpassing the control. Ear wetting (25-50mm) once at harvest maturity resulted in greater subsequent seed longevity than wetting for several days or >50mm. Hence direct and indirect and immediate and delayed effects of simulated rainfall were detected; drought improved and rainfall reduced HFN, but seed quality was increased by both.
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Ali, Solaf Jawhar. "Investigating secondary metabolism in Zymoseptoria tritici." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.687598.
Повний текст джерелаАнотація:
One of the most serious fungal diseases of wheat is Septoria tritici Blotch caused by Zymoseptoria tritici. This disease is typified by an asymptomatic latent phase, followed by a rapid onset on host-cell necrosis. There has long been debate about whether the necrosis is due to production of secondary metabolite toxins or other effects of the fungus such as use of small protein effectors thereby providing nutrients for fungal growth. Secondary metabolites are mainly classified into polyketides (PKs), non-ribosomal peptides (NRPs), alkaloids and terpenes. Genome analysis of Z. tritici identified nine PKS and two hybrid PKS NRPS pathways in addition to the NRPS believed to be responsible for siderophore biosynthesis. Promoter: GFP fusions were made for all of these candidate toxin synthase genes and their expression followed in vitro and through the disease cycle by confocal microscopy, however only pPKS3 gave any apparent GFP expression in planta. Disruption of PKS3 did not generate any mutant phenotype. In fungi, the phosphopantetheine transferase (PPTase) is needed not only for the PKS and NRPS activation, but also both lysine and siderophore synthesis and its disruption in Z. tritici is reported to have very reduced virulence. The Z. tritici alpha-aminoadipate reductase (Lys2) gene was disrupted and the ZtΔlys2 mutant was auxotrophic for lysine. Furthermore, the pathogenicity testing of ZtΔlys2 on wheat showed a significant reduction in symptom development and the pycnidia and spore number compared with a wild type. In a parallel experiment, ornithine N hydroxylase (SidA) was disrupted to prevent hydroxamate siderophore synthesis. The resulting ZtΔlys2 mutant was unable to synthesise ferrichrome and required supplementation with a high concentration of iron. It was more sensitive to oxidative stress compared with wild type and showed reduction of pycnidia and spore numbers. Whilst L1PPTstrain shows reduced virulence, the impacts of lysine and iron uptake are sufficient to account for the reduction in virulence so given that these genes also had very low if any expression in planta, it is unlikely that PKS and hybrid PKS NRPS play a major role in disease of Z. tritici.
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Livesey, Nancy L. "Towards the haploid production of transgenic wheat (Triticum aestivum L.)." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395623.
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Xanthopoulos, Georgios. "Simulation of heat and mass transfer and biological changes in a grain store." Thesis, University of Newcastle upon Tyne, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394568.
Повний текст джерела
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Uawisetwathana, Umaporn. "Metabolomics analysis of brown planthopper (BPH)-resistant traits in Thai Jasmine rice (Oryza sativa)." Thesis, Queen's University Belfast, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.696327.
Повний текст джерелаАнотація:
A metabolomics platform technology was used to study known traits of Thai rice, brown planthopper (BPH) resistance trait. Three rice varieties with different BPH resistance capacity, namely BPH-susceptible KD cultivar, BPH-resistant IL7 containing Bph 3 and BPH-resistant+ IL308 containing Bph 3 and terpene synthase (TPS) genes, were analyzed to identify differential metabolomics profiles between them, with and without BPH infestation at different time points (Days 1, 2, 3, 4 and 8). Metabolic profiles were obtained using the analytical methods including Proton Nuclear Magnetic Resonance (1 H NMR) Spectroscopy, Gas Chromatography-Mass Spectrometry (GC-MS) and Ultra Performance Liquid Chromatography Quadrupole Time of Flight -Mass Spectrometry (UPLC-QToF-MS). The metabolomics data were analysed using multivariate statistical analysis to reveal metabolite markers underlying those traits. Different physiological responses from the three varieties were observed in leaves which were dependent on the level of BPH resistance. Untargeted metabolome profiling of rice leaves obtained by 1 H NMR provided thirty primary metabolites profiles revealing the separation between early and late responses. UPLC-QToF-MS method provided more sensitivity and coverage of compounds, hence, it revealed the effective secondary metabolites differences in the early response between the resistant+ IL308 and the other examined (KD and IL7) varieties. Besides, target fatty acid analysis identified fourteen potential fatty acid associated with the BPH resistance. The overall metabolic pathways obtained by the three different methods suggested that BPH infestation causes the metabolic perturbations in transamination, amino acid metabolism, shikimate, purine/pyrimidine, gluconeogenesis, phenylpropanoid and fatty acid pathways. The susceptible and the resistant rice varieties were likely to employ different pathways to fight against BPH infestation. This study identified several potential metabolic pathways of Thai Jasmine rice and its BPH-isogenic lines that can play a role in acclimatization and defense mechanisms against BPH infestation.
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Samsudin, Nik Iskandar Putra Bin. "Potential biocontrol of fumonisin B1 production by Fusarium verticillioides under different ecophysiological conditions in maize." Thesis, Cranfield University, 2015. http://dspace.lib.cranfield.ac.uk/handle/1826/9620.
Повний текст джерелаАнотація:
Fusarium verticillioides contaminates maize with the fumonisin group of mycotoxins for which there are strict legislative limits in many countries including the EU. The objectives of this project were (a) to examine the microbial diversity of maize samples from different regions and isolate potential biocontrol agents which could antagonize F. verticillioides and reduce fumonisin B1 (FB1) production, (b) to screen the potential biocontrol candidates using antagonistic interaction assays and different ratios of inoculum on maize-based media and on maize kernels to try and control FB1 production, (c) to examine whether the potential control achieved was due to nutritional partitioning and relative utilization patterns of antagonists and pathogen, and (d) to examine the effects of best biocontrol agents on FUM1 gene expression and FB1 production on maize cobs of three different ripening stages.
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Lee, Jack Alexander. "The use of virus induced gene silencing to investigate Septoria leaf blotch in wheat." Thesis, Durham University, 2016. http://etheses.dur.ac.uk/11465/.
Повний текст джерелаАнотація:
Septoria leaf blotch, caused by the fungal pathogen Zymoseptoria tritici, is one of the most damaging diseases of wheat (Triticum aestivum), a crop plant of significant worldwide importance. Using the system of Virus-Induced Gene Silencing, to create transient knockdowns of target genes, a novel wheat gene, TaR1, was identified as playing a key role in the host response to this pathogen. Silencing this gene leads to the earlier onset of disease symptoms, but reduced reproduction of the causal pathogen. Sequence analysis, confocal microscopy and protein-protein interaction assays were used to determine that the protein TaR1 localises the nucleus, where its function involves the binding of histones. Precisely, TaR1 is able to bind the Histone 3 subunit, specifically methylated on Lysine 4. Through this action, the host defence response is delayed, and successful pathogen colonisation is promoted. It is hypothesised that this is an example of the pathogen ‘hi-jacking’ TaR1 from its original function, in order to complete its lifecycle.
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Shorinola, Oluwaseyi. "Understanding the genetic and physiological control of pre-harvest sprouting and pre-maturity amylase in UK wheat." Thesis, University of East Anglia, 2015. https://ueaeprints.uea.ac.uk/58447/.
Повний текст джерелаАнотація:
Pre-harvest sprouting (PHS) and Pre-maturity amylase (PMA) are physiological defects in wheat grains that reduce their end-use quality. PHS is the precocious germination of grains before harvest while PMA is the accumulation of α-amylase in grains. Both traits are quantitative in their expression and are strongly influenced by the environment. In this project, I studied six Quantitative Trait Loci (QTL) located on chromosomes 1A, 2D, 3A (2 loci), 4A and 7B, which confer resistance to PHS or PMA in UK wheat varieties. The aims of this project were to validate and characterise the effects of these QTL, as well as to fine-map the QTL with the most significant effect. To achieve these aims, isogenic materials were developed to independently study these QTL effects. Physiological characterisation of these QTL showed that they exert their effects by affecting the dynamic of dormancy loss in grains, albeit at different stages of grain development and maturation. We also show that temperature during grain development and germination affect the expression of these QTL effects. In addition to the characterisation above, I also undertook the fine-mapping and positional cloning of the 4A QTL (named Phs), as this QTL showed the highest effect on PHS resistance of all the QTL studied. I took advantage of recent advances in wheat genomics, high-throughput genotyping and the syntenic relationship between wheat and other grasses, to delimit Phs to a less than 0.2 cM interval. Furthermore, examination of the physical map of this interval identified 17 genes with varied biological functions. High-resolution fine-mapping of the 0.2 cM interval in three independent and diverse populations further delimited Phs to a 10 kb genomic interval. Finally, I report on the comparative sequence analysis around this critical interval, and show the presence of some genomic lesions that could be critical for the Phs effect.
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Johnson, Stephanie. "The mechanisms of drought stress tolerance in the crop Sorghum bicolor." Thesis, Durham University, 2016. http://etheses.dur.ac.uk/11426/.
Повний текст джерелаАнотація:
Drought stress can have a major impact upon plant survival and crop productivity. Sorghum bicolor is an important cereal crop grown in the arid and semi-arid regions of >98 different countries. It is well adapted to the harsh drought-prone environments in which it is grown however; relatively few studies have investigated the molecular basis of these adaptations. Breeding programs have lead to the identification of ‘stay-green’ varieties, so-called due to their ability to maintain green photosynthetic leaf area for longer under drought conditions. However, despite extensive breeding efforts to select for this trait we have very little understanding of the fundamental biological processes that underlie it. Microarray analysis was used to identify gene expression changes in sorghum following heat stress, drought stress and combined heat and drought stress. These microarrays were additionally used to compare gene expression in stay-green (drought-tolerant) and senescent (drought-sensitive) sorghum lines. Ontological analysis of the genes expressed to higher levels in the stay-green lines identified key processes hypothesised to be associated with the trait. These include genes associated with proline and betaine biosynthesis, glutathione S-transferase (GST) activity and the regulation of stomatal aperture and density. Both proline levels and GST activity were found to be higher in the stay-green lines thus validating that the changes at the gene expression level result in changes at the protein level. Stay-green lines were also shown to have reduced transpiration and reduced numbers of stomata. Two signalling genes, DREB1A and SDIR1 were expressed to higher levels in the stay-green varieties. Transgenic lines overexpressing these genes were generated in order to test their function. Based on the gene expression data, putative mechanisms underlying two QTL for the stay-green trait (Stg1 and StgB) were generated. Further validation of these genes and processes could not only improve our understanding of drought tolerance mechanisms in sorghum, but also facilitate the improvement of future sorghum cultivars.
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Dawson, Andrew. "Elucidating the molecular genetics of host and nonhost resistance in barley to stripe rust." Thesis, University of East Anglia, 2015. https://ueaeprints.uea.ac.uk/58560/.
Повний текст джерелаАнотація:
Plants have a remarkable ability to resist the majority of pathogenic microbes they encounter. As such, they are described as nonhosts. Nonhost resistance is often conceptualised as a qualitative separation from host resistance. Classification into these two states is generally facile, as they fail to fully describe the range of states that exist in the transition from host to nonhost. This poses a problem when studying pathosystems that cannot be classified into either of these categories due to their intermediate status relative to the two extremes. Therefore, the terms intermediate host and intermediate nonhost have been proposed to describe pathosystems in the evolutionary transition between host and nonhost status. At present, a significant amount of research exists into the molecular genetics of host and nonhost pathosystems but very little is known about intermediate systems. The work in this Ph. D. thesis focuses on the interaction of barley with Puccinia striiformis f. sp. tritici, the causal agent of wheat stripe rust, as an intermediate host pathosystem. The first research chapter describes the development of two microscopic phenotypic assays used to quantify P. striformis f. sp. tritici in barley leaves challenged with the pathogen. These assays are then used to screen a large panel of barley accessions to define the intermediate host status of barley relative to a host pathosystem. Subsequently, these assays play a key role in determining that the genetic architecture of resistance in barley is underpinned by three major effect resistance loci: Rpst1, Rpst2, and Rpst3. Using a combination of classical map-based genetics and contemporary genomics information I identify a candidate NLR gene underlying Rpst2 resistance on chromosome 7HL. Furthermore, I show that distinct genes condition host and nonhost resistance in barley by mapping the host resistance gene, rps2 to chromosome 2HL.
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Narawatthana, Supatthra. "The regulation of leaf thickness in rice (Oryza sativa L.)." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/4560/.
Повний текст джерелаАнотація:
The regulation of leaf thickness in rice (Oryza sativa L.) S. Narawatthana One of the most important targets to improve crop yield is leaf photosynthetic capacity. Leaf thickness is one parameter closely associated with photosynthetic function and is strongly influenced by the level of irradiance. Generally, high light grown leaves are thicker, have higher light-saturated rates of photosynthesis, higher amounts of Rubisco and a higher chlorophyll a:b ratio than shade grown leaves. However, the developmental stage at which leaf thickness is set and how it is set are unclear. In this thesis I investigate the outcome on leaf thickness of changing irradiance level at specific points in the development of leaf 5 of rice plants via a series of transfer experiments from high light (HL) to low light (LL) at specific stages of leaf development. The results from these experiments show that the P2- to P4-stage of rice leaf development represents a developmental window during which final thickness can be altered via light regime. Analysis of photosynthetic capacity and gas exchange of the leaves from the transfer experiments indicated some correlation of leaf thickness with biochemical/physiological adaptation to the prevailing irradiance level. Interestingly, whilst HL induced the development of thicker rice leaves with a visibly larger mesophyll cell size, transferral of the leaves to LL conditions at any developmental stage led to a LL-acclimated photosynthetic response. To identify lead genes potentially involved in the growth response of young leaves to the prevailing light environment, I performed a microarray analysis of leaf primordia at P3-stage undergoing a leaf-thickness response to altered irradiance level. A number of lead genes were identified and a selection process based on independent expression analyses was performed to narrow the number of candidates for future functional analysis. An initial analysis of some of these genes is reported.
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German, Richard Neil. "The role of landscape context in biological control of cereal aphids." Thesis, University of Leeds, 2012. http://etheses.whiterose.ac.uk/4165/.
Повний текст джерелаАнотація:
Producing enough food to sustainably meet the demands of a growing global population is one of the greatest challenges we face. In wheat, 8% of yield is lost to insect herbivores before harvest, so improving pest control would contribute significantly to food security. Given the negative effects of chemical insecticides, managing habitat to boost numbers of pest natural enemies offers a promising alternative. Recent studies highlight the importance of wider landscape context for natural enemy management, but there is uncertainty over which landscape characteristics are most important for different natural enemies, how this varies temporally, and which management strategies are worthwhile. In this thesis novel analytical approaches using random forests were used to explore temporal and inter-specific variation in the influence of landscape context on species of aphid and hymenopterous parasitoid in winter wheat fields in the UK, and to produce models predicting the abundance of aphids, parasitoids and syrphid larvae as functional groups. Aphid and parasitoid numbers responded strongly to the spatial configuration of vegetation parcels, both being more common in more fine-grained landscapes. Syrphid larvae were more abundant when arable land was rare within 1500 metres. Seasonal variation in landscape influence was more important than annual or inter-species differences for both aphids and parasitoids. Map-based simulations were then performed to predict the outcome of hypothetical land-use scenarios, using a novel method based on statistical models. Displacement of non-crop vegetation by arable land, alongside increased aggregation, produced consistently undesirable results. Estimates of the economic value of natural enemies to farmers were made, showing the potential to reduce yield loss and insecticide cost by at least £55 per hectare through beneficial habitat management. At high aphid densities, natural enemies were more valuable under insecticide free management. Future work and implications of these results are discussed in chapter 6.
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Sutcliffe, Chloe Angelica Jane. "Adoption of improved maize cultivars for climate vulnerability reduction in Malawi." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7794/.
Повний текст джерелаАнотація:
The projected negative impacts of climate change threaten to endanger smallholder rain-fed maize production and therefore food security across Sub-Saharan Africa. It is widely advocated that the provision of improved, climate-tolerant maize seeds will overcome this problem by enabling agricultural adaptation to changing weather conditions. However, attempts to launch new agricultural technologies in Africa have rarely successfully transformed prospects for the most vulnerable, and historical uptake of improved maize has remained low in some countries, including Malawi, despite a strong political legacy of modern input promotion. This thesis investigates how social dimensions (such as asset ownership, cultural preferences and perceptions of climate risk) affect the potential for cultivar adoption to enable equitable adaptation to climate change amongst smallholder maize farmers in Malawi. National strategies for the diffusion of maize cultivars are explored and analysed with reference to agricultural innovation theory. Adoption outcomes are then assessed using household data from two case study areas selected on the basis of their contrasting climate vulnerability characteristics and productive potentials for maize. Lastly, perceptions of climate change amongst research participants are explored and considered in relation to a statistical analysis of historical rainfall and temperature data within the two research areas, Kasungu and Ngabu. The empirical findings reveal that whilst Malawi’s maize seed industry is modernising, changes do not necessarily benefit smallholders, and access to cultivars and information about them remains unequal. State agricultural policies lack regional contextual specificity and have contributed to heightened vulnerability in Ngabu (the less productive case study area). Stakeholders’ perceptions and attitudes about current and future climate change reveal incongruities and misconceptions. Widespread beliefs that seasons are shortening are driving preferences for short season hybrid cultivars, which increasingly flood the seed market, but statistical analysis of historical seasonal rainfall data reveals no clear seasonal trend in this direction. New diffusion strategies, increasing policy sensitivity for dealing with climate vulnerability in marginal areas, and better understanding and communication about climate variability and change will all be required if cultivar adoption is to enable successful and equitable adaptation for Malawian smallholders. These goals could be better supported if vulnerability reduction, rather than corporate growth, was made central to the development of Malawi’s agricultural innovation system. Practical methods by which this change might be achieved are discussed.
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Goddard, Rachel. "Avoiding trade-off when enhancing Fusarium head blight resistance of barley." Thesis, University of East Anglia, 2015. https://ueaeprints.uea.ac.uk/59400/.
Повний текст джерелаАнотація:
Fusarium head blight (FHB) is an economically important disease of barley caused by mycotoxin-producing Fusarium species. Resistance to FHB is associated with several agronomic traits, particularly height. Taller cultivars are generally more resistant; however increased height is less favourable due to the prospect of lodging, creating a trade-off between disease resistance and agronomic qualities. Disease assays with pathogens of differing trophic lifestyles were conducted using barley BRI1 mutation lines, which display brassinosteroid (BR) insensitivity and a semi-dwarf phenotype. Interestingly, bri1 semi-dwarf lines did not display increased susceptibility to FHB. Additionally, bri1 mutation provided advantageous resistance to necrotrophs but did not increase susceptibility to biotrophs, demonstrating an absence of a resistance trade-off. The barley cultivars Chevallier and Armelle display significant FHB resistance, yet also possess a tall height phenotype. To determine whether the resistance of these cultivars was associated with height, bi-parental populations were created by crossing to the short, modern variety NFC Tipple. High density genetic maps of the populations were produced using Genotyping-by-Sequencing and 384-SNP BeadXpress assays to enable quantitative trait loci (QTL) mapping of both FHB and agronomic traits. Within the C×T population, a QTL for FHB resistance was identified on chromosome 6H which was not associated with either height or heading date, suggesting that resistance in this region is not due to linkage or pleiotropy with these traits. In contrast, FHB resistance within the A×T population was coincident with both height and heading date QTL on 3H. QTL analysis of malting traits of Chevallier, an English malting landrace, was also undertaken. Chevallier compared favourably to NFC Tipple, a modern malting cultivar, for several malting characteristics including free amino nitrogen, diastatic power and wort β-glucan content. This demonstrates that Chevallier may be a useful potential source of both FHB disease resistance and quality traits.
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Frizell-Armitage, Amelia. "The effect of non-glaucousness, as conferred by Inhibitor of Wax 1, on physiology and yield of UK wheat." Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/59421/.
Повний текст джерелаАнотація:
As the first barrier to the external environment, the epicuticular waxes have a number of key roles in plant physiology. Although the wheat wild progenitors display a diversity of epicuticular wax phenotypes, the glaucous (visible wax) phenotype dominates cultivated varieties. However, the UK winter wheat variety Shamrock is unusual in that it exhibits a non-glaucous phenotype, conferred by the wild emmer gene Inhibitor of Wax 1 (Iw1). UK field trials with Shamrock associated a yield advantage of 4.15% with Iw1. This PhD tests the hypothesis that Iw1 imparts an advantage for wheat yield and physiology in the UK. Crossing Shamrock with six glaucous UK winter wheat varieties (Malacca, Alchemy, Hereward, Xi19, Robigus and Einstein) created non-glaucous near isogenic lines (NILs) with Iw1. NILs were grown at multiple field trial locations in the east of England over four years. A long-term shade trial reducing incoming light by 40 and 60% was also carried out in 2014. Yield, and various physiological components including water use efficiency (WUE) and spectral properties, were measured. Iw1 reduced flag leaf photosynthetically active radiation (PAR) reflectance by 15-40% and canopy reflectance by 12-20% (p<0.05). Despite this, Iw1 did not affect flag leaf PAR absorbance or canopy temperature, and conferred no advantage under long-term shading. Furthermore, there was no difference between NILs in photoinhibition following an extended period of high light stress. Iw1 did not affect WUE or yield. However, non-glaucous Hereward and Alchemy NILs yielded 4.96±1.15% (p<0.001) and 2.59±1.01% (p=0.045) more than their glaucous counterparts, although this advantage did not map to Iw1. Iw1 offered no advantage to UK winter wheat under normal UK growing conditions, nor under long-term shading. However, the yield advantage associated with the Iw1 introgression in Hereward and Alchemy is significant within a backdrop of plateauing wheat yields and worth pursuing.
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Redfern, James. "Performance of cereal aphids in relation to genetic variation and nitrogen use efficiency of wheat (Triticum aestivum)." Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/59627/.
Повний текст джерелаАнотація:
In this thesis I address the question: does breeding to improve nitrogen use efficiency of winter wheat, Triticum aestivum, increase its susceptibility to infestation by cereal aphids? Laboratory and greenhouse experiments were used to monitor population performance of the aphids Sitobion avenae and Metopolophium dirhodum on double haploid genotypes of a Savannah cross Rialto (SavRia) wheat population. The genotypes varied in nitrogen use efficiency and its two components: nitrogen uptake efficiency and nitrogen utilisation efficiency. A quantitative trait loci analysis, using 94 genotypes grown under greenhouse and laboratory conditions, identified genetic markers associated with individual performance and population measures of S. avenae and M. dirhodum. Twelve markers across chromosomes on the SavRia genetic map were statistically associated with nine of the fourteen aphid performance traits measured. Nine wheat genotypes, representing the range of nitrogen use efficiencies, were used to analyse how aphid development rate, fecundity and intrinsic rate of increase, varied between genotype and whether settling behaviour and preference between genotypes, reflected differences in performance. Significant differences in performance of S. avenae between different genotypes were found but performance was not correlated with plant nitrogen uptake. In a randomised split plot experiment in the field, six SavRia genotypes and both parental varieties were grown under three application rates of nitrogen fertiliser. Significant variation between genotypes and between different nitrogen application rates was observed for eight plant traits, including both nitrogen uptake and utilisation efficiencies. Density of S. avenae differed significantly between genotypes with significant genotype x nitrogen application rate interactions. Aphid densities were not significantly correlated to either components of nitrogen use efficiency. I conclude that this study does not support the hypothesis that increasing nitrogen use efficiency, or either of its primary components, increases the susceptibility of winter wheat to infestation by cereal aphids.
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Ghanbari-Bonjar, Ahmad. "Intercropping wheat (Triticum aestivum, L.) and bean (Vicia faba, L.) as a a low input forage." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.589767.
Повний текст джерела
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Kowalski, Ania. "The agronomic and molecular characterisation of Rht8 in hexaploid wheat." Thesis, University of East Anglia, 2015. https://ueaeprints.uea.ac.uk/59230/.
Повний текст джерелаАнотація:
Reduced height 8 (Rht8) is the main alternative to the GA-insensitive Rht alleles in hot and dry environments and reduces plant height without yield penalty. The potential of Rht8 in northern-European wheat breeding remains unclear. In the present study, near-isogenic lines contrasting for the Rht8/tall allele in the UK-adapted and photoperiod-sensitive variety Paragon were evaluated in trials with varying nitrogen fertiliser (N) treatments and water regimes across sites in the UK and Spain. Rht8 conferred a robust height reduction of 11% regardless of treatment and was more resistant to root-lodging at agronomically-relevant N levels. In the UK, the Rht8 NIL showed a 10% yield penalty due to concomitant reduction in grain number and spike number whereas grain weight and harvest index were not significantly different to the tall NIL. The yield penalty was abolished at low N and in irrigated conditions in the UK and Spain. This indicates the utility of Rht8 in reduced-input agriculture. Decreased spike length and constant spikelet number in Rht8 compacted spikes by 15% independent of environment. The genetic interval of Rht8 overlaps with the most recent mapping of the compactum gene on 2DS (Johnson et al., 2008) and future work with the markers found in this study is required to genetically dissect these loci. Rht8 had been previously fine-mapped to a 1.29 cM interval (Gasperini et al., 2012). Rht8 was further fine-mapped using an RNA-Seq enabled bulked segregant analysis method, as well as utilising SNP-platforms and emerging Triticeae genomic resources to identify molecular markers. Rht8 was reduced to a 1.015 cM genetic interval and syntenic intervals of 1.34 Mb on rice chromosome 4, 1.36 Mb on Brachypodium chromosome 5, 2.9 Mb on barley 2H and 4.25 Mb on Ae. tauschii 2D. Disruption to micro-collinearity was found with Brachypodium and rice, with better but imperfect collinearity with Ae. tauschii and barley. Rht8 was also anchored to a single IWGSC-2 POPSEQ bin and to a 2.3 cM region in the whole genome shotgun-ordered wheat scaffolds.
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Al-Harbi, Asmaa Ali. "A proteomics-based approach to studying the impact of transgenic maize (MON810) in rats as a model." Thesis, University of Newcastle upon Tyne, 2015. http://hdl.handle.net/10443/3016.
Повний текст джерелаАнотація:
Transgenic maize MON810 is a maize variety that has been genetically modified to express Cry1Ab isolated from the soil bacterium Bacillus thuringiensis (Bt) to produce a natural insecticide (Bt toxin) which kills larvae of the European corn borer (ECB), a major pest of maize. The mode of action of Bt toxin in ECB is through binding to specific receptors on the epithelial cells of the highly alkaline midgut of the insect, resulting in pore-formation, osmotic imbalance, cell lysis and subsequent death of the insect. In contrast, this Bt toxin is considered to be harmless or nontoxic to mammals due to acidified gut pepsinolysis and the lack of Cry protein binding-sites on the mammalian gut epithelial cells. However, to date, no studies have investigated the cellular effects of these Cry proteins at the proteome level. The aim of this study was therefor to investigate the in vivo and in vitro effects of MON810 maize expressing the δ-insecticidal protein Cry1Ab from Bacillus thuringiensis, on differential gene expression at the proteome level in the epithelial cells of the small intestine of the rat as a model for mammals. Proteomic profiling techniques were included for the in vivo and in vitro studies to obtain a better understanding of the underlying molecular responses in rat to MON810. Transgenic Bt maize (MON810), the corresponding parental non-transgenic maize (MON CONV CORN), and 3 other maize varieties, MON Garst 8450, MON Gold HVST H8920 and MCert Rod commercial control (used as internal controls), were provided by Monsanto, USA. All diets were formulated by TestDiet and contained approximately 33% (w/w) corn grain; other diet components were adjusted to provide approximately equal levels of protein, calories and nutrients. Different reference varieties were used in this study to determine whether the changes that may occur with the consumption of MON810 maize lay within the expected range for several different unmodified reference varieties. Two rats feeding trials (7-day and 28-day) were conducted to assess the safety of MON810 maize using forty immature male Wistar rats (rats were between 6 to 7 weeks of age at the beginning of the study). Rats were assigned to the above 5 experimental groups based on body weight means. No adverse behavioural effects on rats were observed and there were no significant differences in absolute body weights, body weight gains, food consumption and feed conversion efficiency between rats fed MON810 in the diet when compared to rats fed diets containing grain from the other maize varieties. Thus the transgenic variety MON810 had no adverse effects on these parameters. Following these feeding studies, rats were sacrificed and the total proteins extracted from the small intestinal epithelial cells were separated by 2D gel electrophoresis. Differentially expressed proteins were identified using SameSpot Progenesis software followed by liquid chromatography–mass spectrometry (LC-MS/MS); the mass spectrometry data were analysed by Global Proteome Machine (GPM) search engine for protein identification. The same proteomic profiling techniques were used for the in vitro approaches for MON810 maize safety evaluation where primary intestinal epithelial cells and HCT116 cell line were used. In vivo effects of these different maize varieties on the proteome of the epithelial cells of the small intestine when all five groups were compared showed that there were 5, 4, 3, 0, 0, differentially expresed protein spots for Mcert, Mon Conv Corn, MON810, Mon Garst and MON Gold, respectively for the 7- day trial. Two stress-related proteins (LDLR chaperone MESD precursor and peroxiredoxin-6) were up-regulated (2.4 fold) in the MON810 group and 1 stress-related protein (thioredoxindependent peroxide reductase) was up-regulated (2.6 fold) in the Mcert group. For the 28-day trial, only 2 proteins spots (representing 6 proteins) were up-regulated in the small intestinal epithelial cells of rats fed MON810, one of which was a stress-related protein (stress-induced phosphoprotein 1; 3.1 fold). In vitro effects of MON810 and its near isogenic line on the proteome of the epithelial cell lines were negligible, with only 4 protein spots (5 stress-related protein) being up-regulated in the small intestinal primary epithelial cells (IE cells) when exposed to Bt maize extracts and 2 protein spots (1 stress-related protein) being up-regulated when exposed to non-Bt maize extracts. There were no differentially expressed spots between the HCT116 cell lines. The findings from the in vivo and in vitro studies both suggest that MON810 has negligible effects on rats at the cellular level. They also confirm the lack of mammalian toxicity when using rats as a model system.