Academic literature on the topic 'Fungal root pathogens'
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Journal articles on the topic "Fungal root pathogens"
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Castellanos-Morales, V., R. Cárdenas-Navarro, J. M. García-Garrido, A. Illana, J. A. Ocampo, S. Steinkellner, and H. Vierheilig. " Bioprotection against Gaeumannomyces graminis in barley a comparison between arbuscular mycorrhizal fungi." Plant, Soil and Environment 58, No. 6 (June 18, 2012): 256–61. http://dx.doi.org/10.17221/622/2011-pse.
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Gaeumannomyces graminis var. tritici causes take-all disease, the most important root disease of cereal plants. Cereal plants are able to form a symbiotic association with soil-borne arbuscular mycorrhizal fungi which can provide bioprotection against soil-borne fungal pathogens. However, the bioprotective effect of arbuscular mycorrhizal fungi against soil-borne fungal pathogens might vary. In the present study we tested the systemic bioprotective effect of the arbuscular mycorrhizal fungi Glomus mosseae, Glomus intraradices and Gigaspora rosea against the soil-borne fungal pathogen Gaeumannomyces graminis var. tritici in a barley split-root system. Glomus intraradices, Glomus mosseae and Gigaspora rosea colonized the split-root system of barley plants at different levels; however, all arbuscular mycorrhizal fungi clearly reduced the level of root lesions due to the pathogen Gaeumannomyces graminis. Our data indicate that some arbuscular mycorrhizal fungi need high root colonization rates to protect plants against fungal pathogens, whereas others act already at low root colonization rates.
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Loit, Kaire, Liina Soonvald, Alar Astover, Eve Runno-Paurson, Maarja Öpik, and Leho Tedersoo. "Temporal and Cultivar-Specific Effects on Potato Root and Soil Fungal Diversity." Agronomy 10, no. 10 (October 9, 2020): 1535. http://dx.doi.org/10.3390/agronomy10101535.
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The soil fungal community plays an important role in determining plant growth and health. In this study, we investigated the fungal diversity and community composition in the roots and soil of 21 potato (Solanum tuberosum L.) cultivars using high-throughput sequencing at three different time points across the growing season. In soil and roots, the fungal richness and relative abundance of pathogens and saprotrophs were mainly affected by sampling time. While sampling time affected fungal composition in soil, root fungal communities were also significantly affected by cultivar. The cultivar had the strongest effect on diversity of pathogens and abundance of particular pathogen species. Our results demonstrate changes in soil and root fungal communities of potato over the growing season, as well as highlighting the importance of potato cultivar on root fungal communities and abundance of pathogens.
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Traquair, James A. "Fungal biocontrol of root diseases: endomycorrhizal suppression of cylindrocarpon root rot." Canadian Journal of Botany 73, S1 (December 31, 1995): 89–95. http://dx.doi.org/10.1139/b95-230.
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Many reviews in the past decade outline the need to understand the complex interactions between fungal pathogens of roots, mycorrhizal fungi, mycorrhizosphere associates, and various climatic and edaphic factors to develop stable mycorrhizal biocontrol strategies. Cylindrocarpon root rot caused by Cylindrocarpon destructans is a good example of a replant disorder that is amenable to this type of control in nurseries and new or renovated orchard sites. Cylindrocarpon root rot was reduced by endomycorrhizal colonization of potted peach rootstocks with Glomus aggregatum under controlled environment conditions using Turface or natural, untreated orchard soils. Several mechanisms of suppression are discussed including tolerance to the pathogen through increased host vigor and reduced exudation, competition for space and nutrients, and induced host resistance. Technical innovations and new concepts of fungal community ecology are improving the odds of developing effective biocontrols with mycorrhizae. Exploitation of natural and integrated disease management using multiple mechanisms of pathogen inhibition may offset the difficulties in inoculum preparation. Key words: Cylindrocarpon destructans, antagonism, competition, rhizosphere, mycorrhizosphere.
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Delavaux, Camille S., Josh L. Schemanski, Geoffrey L. House, Alice G. Tipton, Benjamin Sikes, and James D. Bever. "Root pathogen diversity and composition varies with climate in undisturbed grasslands, but less so in anthropogenically disturbed grasslands." ISME Journal 15, no. 1 (September 21, 2020): 304–17. http://dx.doi.org/10.1038/s41396-020-00783-z.
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AbstractSoil-borne pathogens structure plant communities, shaping their diversity, and through these effects may mediate plant responses to climate change and disturbance. Little is known, however, about the environmental determinants of plant pathogen communities. Therefore, we explored the impact of climate gradients and anthropogenic disturbance on root-associated pathogens in grasslands. We examined the community structure of two pathogenic groups—fungal pathogens and oomycetes—in undisturbed and anthropogenically disturbed grasslands across a natural precipitation and temperature gradient in the Midwestern USA. In undisturbed grasslands, precipitation and temperature gradients were important predictors of pathogen community richness and composition. Oomycete richness increased with precipitation, while fungal pathogen richness depended on an interaction of precipitation and temperature, with precipitation increasing richness most with higher temperatures. Disturbance altered plant pathogen composition and precipitation and temperature had a reduced effect on pathogen richness and composition in disturbed grasslands. Because pathogens can mediate plant community diversity and structure, the sensitivity of pathogens to disturbance and climate suggests that degradation of the pathogen community may mediate loss, or limit restoration of, native plant diversity in disturbed grasslands, and may modify plant community response to climate change.
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Gao, Ying, Ethan Swiggart, Kaela Wolkiewicz, Prabha Liyanapathiranage, Fulya Baysal-Gurel, Farhat A. Avin, Eleanor F. P. Lopez, Rebecca T. Jordan, Joshua Kellogg, and Eric P. Burkhart. "Goldenseal (Hydrastis canadensis L.) Extracts Inhibit the Growth of Fungal Isolates Associated with American Ginseng (Panax quinquefolius L.)." Molecules 29, no. 3 (January 23, 2024): 556. http://dx.doi.org/10.3390/molecules29030556.
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American ginseng, a highly valuable crop in North America, is susceptible to various diseases caused by fungal pathogens, including Alternaria spp., Fusarium spp., and Pestalotiopsis spp. The development of alternative control strategies that use botanicals to control fungal pathogens in American ginseng is desired as it provides multiple benefits. In this study, we isolated and identified three fungal isolates, Alternaria panax, Fusarium sporotrichioides, and Pestalotiopsis nanjingensis, from diseased American ginseng plants. Ethanolic and aqueous extracts from the roots and leaves of goldenseal were prepared, and the major alkaloid constituents were assessed via liquid chromatography–mass spectrometry (LC–MS). Next, the antifungal effects of goldenseal extracts were tested against these three fungal pathogens. Goldenseal root ethanolic extracts exhibited the most potent inhibition against fungal growth, while goldenseal root aqueous extracts and leaf ethanolic extracts showed only moderate inhibition. At 2% (m/v) concentration, goldenseal root ethanolic extracts showed an inhibition rate of 86.0%, 94.9%, and 39.1% against A. panax, F. sporotrichioides, and P. nanjingensis, respectively. The effect of goldenseal root ethanolic extracts on the mycelial morphology of fungal isolates was studied via scanning electron microscopy (SEM). The mycelia of the pathogens treated with the goldenseal root ethanolic extract displayed considerable morphological alterations. This study suggests that goldenseal extracts have the potential to be used as a botanical fungicide to control plant fungal diseases caused by A. panax, F. sporotrichioides, or P. nanjingensis.
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Wang, Chengxian, Jianfeng Liu, Changmei Wang, Xingling Zhao, Kai Wu, Bin Yang, Fang Yin, and Wudi Zhang. "Biogas slurry application alters soil properties, reshapes the soil microbial community, and alleviates root rot of Panax notoginseng." PeerJ 10 (July 26, 2022): e13770. http://dx.doi.org/10.7717/peerj.13770.
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Background Panax notoginseng is an important herbal medicine in China, where this crop is cultivated by replanting of seedlings. Root rot disease threatens the sustainability of P. notoginseng cultivation. Water flooding (WF) is widely used to control numerous soilborne diseases, and biogas slurry shows positive effects on the soil physiochemical properties and microbial community structure and has the potential to suppress soilborne pathogens. Hence, biogas slurry flooding (BSF) may be an effective approach for alleviating root rot disease of P. notoginseng; however, the underlying mechanism needs to be elucidated. Methods In this study, we conducted a microcosm experiment to determine if BSF can reduce the abundance of pathogens in soil and, alleviate root rot of P. notoginseng. Microcosms, containing soil collected from a patch of P. notoginseng showing symptoms of root rot disease, were subjected to WF or BSF at two concentrations for two durations (15 and 30 days), after which the changes in their physicochemical properties were investigated. Culturable microorganisms and the root rot ratio were also estimated. We next compared changes in the microbial community structure of soils under BSF with changes in WF and untreated soils through high-throughput sequencing of bacterial 16S rRNA (16S) and fungal internal transcribed spacer (ITS) genes amplicon. Results WF treatment did not obviously change the soil microbiota. In contrast, BSF treatment significantly altered the physicochemical properties and reshaped the bacterial and fungal communities, reduced the relative abundance of potential fungal pathogens (Fusarium, Cylindrocarpon, Alternaria, and Phoma), and suppressed culturable fungi and Fusarium. The changes in the microbial community structure corresponded to decreased root rot ratios. The mechanisms of fungal pathogen suppression by BSF involved several factors, including inducing anaerobic/conductive conditions, altering the soil physicochemical properties, enriching the anaerobic and culturable bacteria, and increasing the phylogenetic relatedness of the bacterial community. Conclusions BSF application can reshape the soil microbial community, reduce the abundance of potential pathogens, and alleviate root rot in P. notoginseng. Thus, it is a promising practice for controlling root rot disease in P. notoginseng.
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Toth, Ronald, Deborah Toth, David Starke, and David R. Smith. "Vesicular–arbuscular mycorrhizal colonization in Zea mays affected by breeding for resistance to fungal pathogens." Canadian Journal of Botany 68, no. 5 (May 1, 1990): 1039–44. http://dx.doi.org/10.1139/b90-131.
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Inbred lines of Zea mays L. (maize) selected for a range of resistances to a variety of fungal pathogens were assayed for percentage colonization by vesicular–arbuscular mycorrhizal fungi. Inbreds that were generally resistant to a number of fungal pathogens had significantly lower levels of vesicular–arbuscular mycorrhizae, matured more slowly, and had larger root systems. Disease-susceptible inbreds had significantly higher levels of mycorrhizal colonization, matured more rapidly, and had smaller root systems. It is uncertain if a general resistance to fungal pathogens or rate of root development, separately or in combination, may have influenced mycorrhizal colonization levels. Irrespective of cause, present breeding programs for disease resistance in maize do influence the plants ability to form mycorrhizae.
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Okubara, Patricia A., Amy B. Peetz, and Richard M. Sharpe. "Cereal Root Interactions with Soilborne Pathogens—From Trait to Gene and Back." Agronomy 9, no. 4 (April 13, 2019): 188. http://dx.doi.org/10.3390/agronomy9040188.
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Realizing the yield potential of crop plants in the presence of shifting pathogen populations, soil quality, rainfall, and other agro-environmental variables remains a challenge for growers and breeders worldwide. In this review, we discuss current approaches for combatting the soilborne phytopathogenic nematodes, Pratylenchus and Heterodera of wheat and barley, and Meloidogyne graminicola Golden and Birchfield, 1965 of rice. The necrotrophic fungal pathogens, Rhizoctonia solani Kühn 1858 AG-8 and Fusarium spp. of wheat and barley, also are discussed. These pathogens constitute major causes of yield loss in small-grain cereals of the Pacific Northwest, USA and throughout the world. Current topics include new sources of genetic resistance, molecular leads from whole genome sequencing and genome-wide patterns of hosts, nematode or fungal gene expression during root-pathogen interactions, host-induced gene silencing, and building a molecular toolbox of genes and regulatory sequences for deployment of resistance genes. In conclusion, improvement of wheat, barley, and rice will require multiple approaches.
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Eyles, A., C. Beadle, K. Barry, A. Francis, M. Glen, and C. Mohammed. "Management of fungal root-rot pathogens in tropicalAcacia mangiumplantations." Forest Pathology 38, no. 5 (October 2008): 332–55. http://dx.doi.org/10.1111/j.1439-0329.2008.00549.x.
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Okubara, Patricia A., and Timothy C. Paulitz. "Root Defense Responses to Fungal Pathogens: A Molecular Perspective." Plant and Soil 274, no. 1-2 (July 2005): 215–26. http://dx.doi.org/10.1007/s11104-004-7328-9.
Full textDissertations / Theses on the topic "Fungal root pathogens"
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Omar, Ibrahim. "Biological control of crown and root rot of tomato." Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310952.
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Levenfors, Jens. "Soil-borne pathogens in intensive legume cropping - Aphanomyces spp. and root rots /." Uppsala : Dept. of Plant Pathology and Biocontrol Unit, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/a393.pdf.
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Samils, Nicklas. "Monitoring the control methods of Heterobasidion annosum s.l. root rot /." Uppsala : Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, 2008. http://epsilon.slu.se/200847.pdf.
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Ray, Pushpanjali. "Search for novel actinomycetes from soil as potential biocontrol agent against fungal root pathogens of phaseolus vulgaris (L.) vigna radiata(L.)." Thesis, University of North Bengal, 2017. http://ir.nbu.ac.in/hdl.handle.net/123456789/2575.
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Sjöberg, Johanna. "Arbuscular mycorrhizal fungi : occurrence in Sweden and interaction with a plant pathogenic fungus in barley /." Uppsala : Dept. of Crop Production Ecology, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/200533.pdf.
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Day, Jennifer P. "In vitro studies into host-pathogen interactions of sunflower and Macrophomina phaseolina." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319785.
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Taheri, Abdolhossein. "Interaction between root lesion nematode, Pratylenchus neglectus, and root-rotting fungi of wheat." Title page, contents and summary only, 1996. http://web4.library.adelaide.edu.au/theses/09PH/09pht128.pdf.
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Bibliography: leaves 307-329. This study concludes that in soils in South Australia where root-rotting fungi and P. neglectus exist together, root disease of wheat is caused by their combined effect. Evidence suggests that P. neglectus not only contributes to this interaction through mechanical wounding of roots, but also causes biochemical and physiological changes in plants, making them more prone to fungal infection.
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Porto, Maria Alice Formiga. "Associação de Fusarium solani, Macrophomina phaseolina e Rhizoctonia solani causando podridão radicular em meloeiro sob efeito de adubos verdes." Universidade Federal Rural do Semi-Árido, 2015. http://bdtd.ufersa.edu.br:80/tede/handle/tede/105.
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The occurrence of root diseases is one of the main reasons of yield loss in melon crop, especially the pathogens that causes root and collar rot, as the fungi Fusarium solani (Mart.) Sacc., Macrophomina phaseolina (Tassi) Gold. and Rhizoctonia solani Kuhn, being observed in muskmelon either alone or associated. The use of crop residues and plant materil, besides the improvement in the physical properties of the soil, also favors microbial activity of the species presents in this environment and affects negatively onpathogens population. Therefore, the objective of this work was to evaluate the associations of F. solani, M. phaseolina and R. solani in the incidence and severity of root rot and fresh and dry weight of muskmelon and verify the effect of green manure in root rot caused by these pathogens alone or associated. The experiment was conducted in two stages, in a greenhouse. The first stage evaluated the association of F. solani, M. phaseolina and R. solani causing root rot in melon, using a randomized block design with 8 treatments (F. solani; M. phaseolina, R. solani, F. solani + M. phaseolina, F. solani + R. solani; M. phaseolina + R. solani, F. solani + M. phaseolina + R. solani; non-infested soil) and 8 repetitions with experimental unit of one pot (3.5 L) with 2 plants. The characteristics evaluated were the incidence of root rot in melon plants at the end of the cycle; disease severity based on a scale notes, and the fresh and dry weight of muskmelon. At the second stage, evaluated the effects of green manure in the association of these pathogens in muskmelon, which was conducted one experiment with Jack beans (Canavalia ensiformis L. DC) and another with Pearl millet (Pennisetum glaucum (L.) R. BR.). The experiments were performed simultaneously in a randomized block design with 8 x 4 factorial {8 types of fungi / association (M. phaseolina, R. solani, F. solani, M. phaseolina + R. solani; M. phaseolina + F. solani, R. solani + F. solani; M. phaseolina + R. solani + F. solani; non-infested soil), 4 forms of management [incorporated, in coverage, polyethylene film (mulching) and without managment]} and 4 repetitions. The characteristics evaluated were the incidence of root rot of melon plants at the end of the cycle, and the fresh and dry weight of muskmelon. The results of disease incidence were submitted to the non-parametric test of Kruskal-Wallis and the fresh and dry weight of muskmelon were analyzed by the Scott-Knott test, both with significance level of 5% of probability (α = 0.05%). At stage 1, the treatment with the three pathogens F. solani, M. phaseolina and R. solani associated resulted in lower incidence of plants with symptoms and was not statistically different from the control. The pathogen R. solani was the least prevalent in the associations. The lowest accumulation of fresh and dry matter happened when the soil was infested with Fusarium solani alone. At stage 2, Jack beans in coverage provided lower incidence of root rot in muskmelon with Fusarium solani alone and in triple association (F. solani +M. phaseolina and R. solani). The use of Pearl millet had no effect on root rot incidence in most treatments. In both experiments (Jack beans andPearl millet), Macrophomina phaseolina was the fungus that prevailed in almost all associations. Jack beans and millet did not increase the fresh and dry weight of muskmelon in most treatments
A ocorrência de doenças radiculares representa uma das principais causas de perda de rendimento na cultura do melão, com destaque para os patógenos causadores das podridões de raízes e colos, como os fungos Fusarium solani (Mart.) Sacc., Macrophomina phaseolina (Tassi) Gold. e Rhizoctonia solani Kuhn, sendo observados no meloeiro tanto de forma isolada quanto associada. A utilização de restos de cultura e material vegetal, além de melhorar as propriedades físicas do solo, favorece a atividade microbiana das espécies presentes neste ambiente e interfere negativamente sobre a população de patógenos. Portanto, objetiva-se com este trabalho avaliar as associações dos patógenos F. solani, M. phaseolina e R. solani na incidência e severidade de podridão radicular e na massa da matéria fresca e seca do meloeiro e verificar o efeito de materiais vegetais na podridão radicular causada por estes patógenos isolados ou associados. O experimento foi conduzido em duas etapas, em casa de vegetação, sendo que na primeira avaliou-se a associação de F. solani, M. phaseolina e R. solani causando podridão radicular em meloeiro, quando foi utilizado o delineamento em blocos casualizados com 8 tratamentos (F. solani; M. phaseolina; R. solani; F. solani + M. phaseolina; F. solani + R. solani; M. phaseolina + R. solani; F. solani + M. phaseolina + R. solani; solo não infestado) e 8 repetições, com unidade experimental de 1 vaso (3,5 L) com duas plantas. As características avaliadas foram: incidência de podridão radicular nas plantas de melão no fim do ciclo, severidade da doença com base em escala de notas, além da matéria fresca e seca das plantas de melão. Na segunda etapa, foi avaliado o efeito de materiais vegetais na associação desses patógenos, também em meloeiro, onde foi realizado um experimento com Feijão-de-porco (Canavalia ensiformis L. DC) e outro com Milheto (Pennisetum glaucum (L.) R. BR.). Os experimentos foram conduzidos simultaneamente, em delineamento experimental de blocos casualizados, com esquema fatorial 8 x 4, sendo 8 tipos de fungos/associação (M. phaseolina; R. solani; F. solani; M. phaseolina + R. solani; M. phaseolina + F. solani; R. solani + F. solani; M. phaseolina + R. solani + F. solani; solo sem inoculação), 4 formas de manejo (incorporado, cobertura, mulching e sem manejo) e 4 repetições. As características avaliadas foram: incidência de podridão radicular nas plantas de melão no fim do ciclo, a massa da matéria fresca e seca das plantas de melão. Os resultados de incidência de doença obtidos foram submetidos ao teste não paramétrico de Kruskal-Wallis e a massa damatéria fresca e seca foram analisados pelo teste de Scott-Knott, ambos com nível de significância a 5% de probabilidade (α = 0,05%). Na etapa 1, o tratamento no qual foram associados três patógenos F. solani, M. phaseolina e R. solani propiciou menor porcentagem de plantas com sintomas da doença e não diferiu estatisticamente da testemunha. O fitopatógeno R. solani foi o que menos prevaleceu nas associações. Quando o solo foi infestado com Fusarium solani, isoladamente, o melão obteve baixo acúmulo de matéria fresca e seca. Na etapa II, o feijão-de-porco em cobertura proporcionoiu menor incidência de podridão radicular do meloeiro quando o Fusarium solani estava sozinho e em associação tripla (F. solani +M. phaseolina e R. solani). A utilização do milheto não apresentou efeito na incidência de podridão radicular na maioria dos tratamentos. Tanto na utilização do feijão-de-porco quanto do milheto, M. phaseolina foi o fungo que prevaleceu na maioria das associações nas quais estava presente. O feijão-de-porco e o milheto não proporcionaram aumento na massa da matéria fresca e seca do meloeiro na maioria dos tratamentos
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Wicks, T. J. "Phytophthora crown rot of almond and cherry trees : pathogens, rootstock and scion susceptib[i]lity and control /." Title page, table of contents and summary only, 1987. http://web4.library.adelaide.edu.au/theses/09PH/09phw637.pdf.
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Balbino, Deyse Anne Dias. "Reação de diferentes culturas a Monosporascus cannonballus." Universidade Federal Rural do Semi-Árido, 2015. http://bdtd.ufersa.edu.br:80/tede/handle/tede/111.
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Previous issue date: 2015-02-23Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The fungus M. cannonballus is a thermophilic plant pathogen, associated with the decline of crude oil in cucurbits worldwide. Although frequently associated with this family, which causes the decline of crude oil, this fungus has been reported in other crops, including maize, beans and cotton, and is, however, little known pathogenicity in these species. The objective of this study was to evaluate the susceptibility of cultivars of different host crops cucurbits and not cucurbits, front inoculation of two isolates of M. cannonballus. The present study tested the behavior of two isolates of M. cannonballus, CMM 3646, isolated Boerhavia diffusa roots (Catch pinto) and CMM 2390, isolated from melon roots, compared to 10 crops (tomatoes, beans, sesame, pumpkin, cucumber, melon, watermelon, sorghum, corn and cotton) with two cultivars of each, totaling forty treatments. With the means of this evaluation we calculated the overall index of the disease (IGD). Pathogenicity was confirmed by isolation of the inoculated fungus. The production of the inoculum of strains was made from the PDA culture medium containing the fungus mycelium. The crops were grown in pots containing sterile soil mixture, sand and substrate. After 50 days of culture, the insulation made from the roots of plants. It was found varying degrees of resistance and susceptibility of cultivars evaluated on isolates used. Cultivars of cucurbits were grouped into categories which the highly susceptible front of the CMM-3646 and CMM-2390 isolated. The species belonging to this family were the ones that had higher IGD. The cultivars of tomato and corn had susceptibility behavior to fungal isolates of M. cannonballus. The sorghum cultivars for both isolates of M. cannonballus behaved as moderately resistant. The cultures do not cucurbits such as cotton, sesame and cowpea obtained degrees of resistance to the fungal isolates used
O fungo Monosporascus cannonballus é um fitopatógeno termófilo, associado ao declínio das ramas em cucurbitáceas em todo o mundo. Apesar de ser frequentemente associado a esta família, na qual provoca o declínio das ramas, este fungo tem sido relatado em outras culturas, entre elas o milho, o feijão e o algodão, sendo, no entanto, pouco conhecida a sua patogenicidade nessas espécies. O objetivo deste trabalho foi avaliar a susceptibilidade de cultivares de diferentes culturas hospedeiras cucurbitáceas e não cucurbitáceas, frente a inoculação de dois isolados de M. cannonballus. No presente trabalho foi testado o comportamento de dois isolados de M. cannonballus, CMM 3646, isolado de raízes de Boerhavia difusa (Pega-pinto) e CMM 2390, isolado de raízes de meloeiro, frente a 10 culturas (tomate, feijão, gergelim, abóbora, pepino, melão, melancia, sorgo, milho e algodão) com duas cultivares de cada, totalizando quarenta tratamentos. Com as médias desta avaliação foi calculado o índice geral da doença (IGD). A patogenicidade foi confirmada através do isolamento do fungo inoculado. A produção do inóculo dos isolados foi feita a partir do meio de cultura BDA, contendo micélios do fungo. Os cultivares, foram cultivados em vasos, contendo uma mistura estéril de solo, areia e substrato. Após 50 dias de cultivo, o ensaio foi desmontado e feito o isolamento das raízes das plantas. Foi constatado resistência e diferentes graus de susceptibilidade dos cultivares avaliados aos isolados utilizados. Os cultivares de cucurbitáceas foram agrupadas nas categorias de susceptíveis a muito susceptíveis frente aos isolados CMM-3646 e CMM-2390. As espécies pertencentes a essa família foram as que obtiveram maiores IGD. Os cultivares de tomate e milho tiveram comportamento de susceptibilidade aos isolados fúngicos de M. cannonballus. Os cultivares de sorgo para ambos os isolados de M. cannonballus se comportaram como medianamente resistentes. As culturas não cucurbitáceas como as de algodão, gergelim e feijão-caupi obtiveram graus de resistência aos isolados de fúngicos utilizados
Books on the topic "Fungal root pathogens"
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Thies, Walter Gene. Laminated root rot in Western North America. Portland, Or: U.S. Dept. of Agriculture, Forest Service, Pacific Northwest Research Station, 1995.
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Peterson, Michael James. Sanitation of styroblocks to control algae and seedling root rot fungi. Victoria, B.C: Forestry Canada, 1990.
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Mazzola, Mark. The effect of fungal root pathogens and phenazine antibiotic biosynthesis on the survival of fluorescent pseudomonads in soil habitats. 1990.
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Garrett, S. D. Pathogenic Root-Infecting Fungi. University of Cambridge ESOL Examinations, 2011.
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Laminated root rot in Western North America. [Portland, Or.]: U.S. Dept. of Agriculture, Forest Service, Pacific Northwest Research Station, 1995.
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Bae, Hanhong. RFLP analysis of genetic variation in the laminated-root-rot fungal pathogen of conifers, Phellinus weirii. 1992.
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Ferguson, Brennan Angus. Fungal root pathogen interactions in a mixed conifer forest in the Blue Mountains of northeastern Oregon. 1994.
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Marsden, M. A. Sensitivity of the western root disease model: inventory of root disease. 1992.
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Stirling, Graham, Helen Hayden, Tony Pattison, and Marcelle Stirling. Soil Health, Soil Biology, Soilborne Diseases and Sustainable Agriculture. CSIRO Publishing, 2016. http://dx.doi.org/10.1071/9781486303052.
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Our capacity to maintain world food production depends heavily on the thin layer of soil covering the Earth's surface. The health of this soil determines whether crops can grow successfully, whether a farm business is profitable and whether an enterprise is sustainable in the long term. Farmers are generally aware of the physical and chemical factors that limit the productivity of their soils but often do not recognise that soil microbes and the soil fauna play a major role in achieving healthy soils and healthy crops.
Soil Health, Soil Biology, Soilborne Diseases and Sustainable Agriculture provides readily understandable information about the bacteria, fungi, nematodes and other soil organisms that not only harm food crops but also help them take up water and nutrients and protect them from root diseases. Complete with illustrations and practical case studies, it provides growers and their consultants with holistic solutions for building an active and diverse soil biological community capable of improving soil structure, enhancing plant nutrient uptake and suppressing root pests and pathogens.
The book is written by scientists with many years' experience developing sustainable crop production practices in the grains, vegetable, sugarcane, grazing and horticultural industries.
This book will be useful for: growers, consultants, agronomists and soil chemists, extension personnel working in the grains, livestock, sugarcane and horticultural industries, professionals running courses in soil health/biological farming, and students taking university courses in soil science, ecology, microbiology, plant pathology and other biological sciences.
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Kirchman, David L. Symbioses and microbes. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198789406.003.0014.
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The book ends with a chapter devoted to discussing interactions between microbes and higher plants and animals. Symbiosis is sometimes used to describe all interactions, even negative ones, between organisms in persistent, close contact. This chapter focuses on interactions that benefit both partners (mutualism), or one partner while being neutral to the other (commensalism). Microbes are essential to the health and ecology of vertebrates, including Homo sapiens. Microbial cells outnumber human cells on our bodies, aiding in digestion and warding off pathogens. In consortia similar to the anaerobic food chain of anoxic sediments, microbes are essential in the digestion of plant material by deer, cattle, and sheep. Different types of microbes form symbiotic relationships with insects and help to explain their huge success in the biosphere. Protozoa are crucial for wood-boring insects, symbiotic bacteria in the genus Buchnera provide sugars to host aphids while obtaining essential amino acids in exchange, and fungi thrive in subterranean gardens before being harvested for food by ants. Symbiotic dinoflagellates directly provide organic material to support coral growth in exchange for ammonium and other nutrients. Corals are now threatened worldwide by rising oceanic temperatures, decreasing pH, and other human-caused environmental changes. At hydrothermal vents in some deep oceans, sulfur-oxidizing bacteria fuel an entire ecosystem and endosymbiotic bacteria support the growth of giant tube worms. Higher plants also have many symbiotic relationships with bacteria and fungi. Symbiotic nitrogen-fixing bacteria in legumes and other plants fix more nitrogen than free-living bacteria. Fungi associated with plant roots (“mycorrhizal”) are even more common and potentially provide plants with phosphorus as well as nitrogen. Symbiotic microbes can provide other services to their hosts, such as producing bioluminescence, needed for camouflage against predators. In the case of the bobtail squid, bioluminescence is only turned on when populations of the symbiotic bacteria reach critical levels, determined by a quorum sensing mechanism.
Book chapters on the topic "Fungal root pathogens"
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Pinhey, Sally, and Margaret Tebbs. "The role of fungi." In Plants for soil regeneration: an illustrated guide, 23–27. Wallingford: CABI, 2022. http://dx.doi.org/10.1079/9781789243604.0005.
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Abstract This chapter focuses on the role of fungi. Fungi are a vital part of the mixture of microorganisms found in healthy soil. Fungal associations between plant roots and beneficial fungi are known as mycorrhizae (meaning 'fungus' and 'root'), and form a beneficial or symbiotic relationship with plants growing in the soil. Mycorrhizal fungi also facilitate plant interactions with other soil microbes. These include pathogens, and bacteria that produce vitamins and protect against attack. The most common of the mycorrhizae are divided into the following: (1) ectomycorrhizae; (2) endomycorrhizae; (3) arbuscular mycorrhizae; (4) ericoid mycorrhizae; and (5) orchid mycorrhiza. The role of saprophytes, pathogens and actinomycetes are also discussed.
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Okubara, Patricia A., and Timothy C. Paulitz. "Root defense responses to fungal pathogens: A molecular perspective." In Plant Ecophysiology, 215–26. Dordrecht: Springer Netherlands, 2005. http://dx.doi.org/10.1007/1-4020-4099-7_11.
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Chiwona-Karltun, Linley, Leon Brimer, and Jose Jackson. "Improving Safety of Cassava Products." In Root, Tuber and Banana Food System Innovations, 241–58. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92022-7_8.
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AbstractCassava was domesticated in the Amazon Basin, where Native Americans selected many bitter varieties, and devised methods for detoxifying them. Cassava reached Africa in the sixteenth century, where rural people soon learned to remove the cyanogenic toxins, e.g., by drying and fermenting the roots. Processing cassava to remove the cyanogenic toxins including the cyanide formed during the processing is time consuming. The work is often done by women, while women and men often prefer bitter cassava varieties for social reasons and superior taste and color. In spite of deep, local knowledge of safe processing, traditional foods made with contaminated water may contain bacterial and fungal pathogens. Improper storage may encourage mycotoxins, such as aflatoxin. Recent advances in industrial processing are developing foods that are free of toxins and microbial contamination. Processing and selling cassava leaves is an emerging but fast-growing sector. Cassava leaves also contain cyanogenic toxins normally in higher concentrations than the cassava roots. In the future, more attention must be paid to the safe processing of cassava leaves and roots, especially as food processing becomes increasingly industrialized worldwide.
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Ulrich, Danielle E. M., Steve Voelker, J. Renée Brooks, and Frederick C. Meinzer. "Insect and Pathogen Influences on Tree-Ring Stable Isotopes." In Stable Isotopes in Tree Rings, 711–36. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92698-4_25.
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AbstractUnderstanding long-term insect and pathogen effects on host tree physiology can help forest managers respond to insect and pathogen outbreaks, and understand when insect and pathogen effects on tree physiology will be exacerbated by climate change. Leaf-level physiological processes modify the carbon (C) and oxygen (O) stable isotopic composition of elements taken up from the environment, and these modifications are recorded in tree-rings (see Chaps. 10.1007/978-3-030-92698-4_9, 10.1007/978-3-030-92698-4_10, 10.1007/978-3-030-92698-4_16 and 10.1007/978-3-030-92698-4_17). Therefore, tree-ring stable isotopes are affected by both the tree’s environment and the tree’s physiological responses to the environment, including insects and pathogens. Tree-ring stable isotopes provide unique insights into the long-term effects of insects and pathogens on host tree physiology. However, insect and pathogen impacts on tree-ring stable isotopes are often overlooked, yet can substantially alter interpretations of tree-ring stable isotopes for reconstructions of climate and physiology. In this chapter, we discuss (1) the effects of insects(defoliators, wood-boring, leaf-feeding), pests (parasitic plants), and pathogens(root and foliar fungi) on hostphysiology (growth, hormonal regulation, gas exchange, water relations, and carbon and nutrient use) as they relate to signals possibly recorded by C and O stable isotopes in tree-rings, (2) how tree-ring stable isotopes reveal insect and pathogen impacts and the interacting effects of pathogens and climate on hostphysiology, and (3) the importance of considering insect and pathogen impacts for interpreting tree-ring stable isotopes to reconstruct past climate or physiology.
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Bruhn, Johann N., and Jeanne D. Mihail. "Opportunistically Pathogenic Root Rot Fungi: Armillaria Species." In Ecological Studies, 337–46. New York, NY: Springer New York, 2003. http://dx.doi.org/10.1007/978-1-4613-0021-2_19.
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Kashyap, Priyakshi, Indrani Sharma, Sampurna Kashyap, and Niraj Agarwala. "Arbuscular Mycorrhizal Fungi (AMF)-Mediated Control of Foliar Fungal Diseases." In Arbuscular Mycorrhizal Fungi and Higher Plants, 193–223. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8220-2_9.
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AbstractPlants witness a variety of disease incidences throughout their life, ultimately resulting in reduced plant growth and productivity. Climate change or human interventions have aggravated the incidences of various plant diseases, among which foliar fungal diseases are serious threats. Arbuscular mycorrhizal fungi (AMF) are a mutualistic group of organisms that play a significant role in enhancing plant growth and resilience under varied environmental circumstances. Moreover, it is well established that AMF confers tolerance against several foliar fungal diseases. This chapter highlights how fungal foliar diseases affect plant health and the various roles of AMF in providing resistance to different crop plants. In addition, AMF-mediated alterations in the root system architecture (RSA), modulation of reactive oxygen species (ROS), and reinforcement of the physical barrier that prevents pathogen invasion and establishment have been discussed in detail. Furthermore, the intricate cross talk between AMF and phytohormones or plant metabolites has also been explored. Overall, harnessing the potential of AMF in imparting tolerance against foliar fungal diseases might reduce the reliance on chemical fungicides, thereby introducing an environment-friendly approach for plant protection.
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Strobel, N. E., and W. A. Sinclair. "Role of Mycorrhizal Fungi in Tree Defense Against Fungal Pathogens of Roots." In Defense Mechanisms of Woody Plants Against Fungi, 321–53. Berlin, Heidelberg: Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-662-01642-8_15.
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da Silva Campos, Maryluce Albuquerque. "Applications of Arbuscular Mycorrhizal Fungi in Controlling Root-Knot Nematodes." In Arbuscular Mycorrhizal Fungi and Higher Plants, 225–37. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8220-2_10.
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AbstractMeloidogyne nematodes cause diseases in economically important plants. These sedentary endoparasites modify plant roots, creating feeding sites and leading to the formation of root galls. Arbuscular mycorrhizal fungi (AMF) form mutualistic associations with many plants, enhancing nutrient uptake and overall plant health. AMF can also provide protection against pathogens, making them valuable for biocontrol. Studies have shown that AMF can reduce the number of Meloidogyne galls and eggs while improving plant growth and nutrient absorption, potentially outperforming chemical pesticides. AMF affect Meloidogyne infection at various stages, such as making roots less attractive to nematodes and reducing giant cell formation in galls. There is an increase in the production of protective molecules, compounds, and defense genes in mycorrhizal plants infected by Meloidogyne, standing out phenolic compounds and defense enzymes like peroxidase and polyphenol oxidase. The activation of defense genes and pathways is suggested to play a role in the tolerance of mycorrhizal plants to Meloidogyne. However, there is still a need for further research to understand the physiological and genetic modifications that occur in plants infected by Meloidogyne and associated with AMF.
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Tripathi, S., S. Kamal, I. Sheramati, R. Oelmuller, and A. Varma. "Mycorrhizal Fungi and Other Root Endophytes as Biocontrol Agents Against Root Pathogens." In Mycorrhiza, 281–306. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-78826-3_14.
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Thomashow, Linda, and Peter A. H. M. Bakker. "Microbial Control of Root-Pathogenic Fungi and Oomycetes." In Principles of Plant-Microbe Interactions, 165–73. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-08575-3_18.
Full textConference papers on the topic "Fungal root pathogens"
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Yin, Chuntao. "Disease-induced changes in the rhizosphere microbiome reduced root disease." In IS-MPMI Congress. IS-MPMI, 2023. http://dx.doi.org/10.1094/ismpmi-2023-5r.
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Rhizosphere microbiota, referred to as the second genome of plants, are crucial to plant health. Increasing evidence reveals that plants can change their rhizosphere microbiome and promote microbial activity to reduce plant disease. However, how plant and phytopathogens factor in combination to structure the rhizosphere microbiome and govern microbial selection for adaptation to disease stress remains incompletely understood. In this study, rhizosphere microbiota from successive wheat plantings under the pressure of the soilborne pathogen Rhizoctonia solani AG8 were characterized. Amplicon sequence analyses revealed that bacterial and fungal communities clustered by planting cycles. The addition of AG8 enhanced the separation of the rhizosphere microbiota. The alpha diversity of bacteria and fungi significantly decreased over planting cycles. Compared with rhizosphere bacterial communities, AG8 was a major driver structuring fungal communities. Pathogen-infected monocultures enriched a group of bacterial genera with potential antagonistic activities or abilities for plant growth promotion or nitrogen fixation. Further, eleven bacterial species exhibited antagonistic activities toward Rhizoctonia spp., and four of them displayed broad antagonism against multiple soilborne fungal pathogens. These findings support the potential to improve plant health through manipulating rhizosphere microbiota.
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Mihnea, Nadejda. "Reacția unor linii de tomate la izolatele fungului Alternaria alternata." In VIIth International Scientific Conference “Genetics, Physiology and Plant Breeding”. Institute of Genetics, Physiology and Plant Protection, Republic of Moldova, 2021. http://dx.doi.org/10.53040/gppb7.2021.64.
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The paper presents the results of the appreciation of some tomato lines based on the resistance to the fungal pathogen Alternaria alternata. Culture filtrates (CF) of pathogen in the most cases did not significantly influence for the seed germination. A more obvious impact was manifested in the case of the root and the stem, the deviations from the control constituting -38.2…. -69.6% for the root and -40.7… -72.6% - for the stem. It was found that the greatest importance in the reaction to A. alternata isolates for seed germination had the genotypic factor, and for root and stem growth - the isolation factor - 95.7-91.0%.
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Sasanelli, Nicola, Ion Toderas, Franco Ciccarese, Elena Iurcu-Straistaru, Stefan Rusu, Lidia Toderas, Marek Renčo, et al. "A sustainable management of corky root and root-knot nematodes by the biocontrol agent aphanocladium album isolate MX-95." In International Symposium "Actual problems of zoology and parasitology: achievements and prospects". Institute of Zoology, 2017. http://dx.doi.org/10.53937/9789975665902.08.
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A trial was carried out in a plastic house on tomato to assess the efficacy of the chitinolytic fungus Aphanocladium album isolate MX-95 (AA MX-95) against the soil borne pathogen Pyrenochaeta lycopersici and the root-knot nematode Meloidogyne incognita. Treatments were: a) AA MX-95 applied in sub irrigation at 2.5 L/plot (1.2 x 107 CFU/mL, conidial suspension) in pre transplant (20 days), transplant and in post transplant (2 times every 20 days) + root dipping (5 min – conc. 1.2 x 107 CFU/mL) at transplant); b) as before indicated without treatment in pre transplant; c) root dipping and d) dazomet (chemical control) applied 30 days before transplant at 600 Kg/ha. Untreated plots served as control. A significant yield increase and a reduction of severity of corky root and nematode attacks were observed in AA MX-95 and dazomet treated plots in comparison to control. High positive correlations were found between the symptoms caused on tomato roots by M. incognita and P. lycopersici.
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Стратулат, Татьяна, Татьяна Щербакова, Штефан Кручан, and Андрей Лунгу. "Пораженность листвы древесных насаждений города Кишинева комплексом гнилей летом 2021 года." In VIIth International Scientific Conference “Genetics, Physiology and Plant Breeding”. Institute of Genetics, Physiology and Plant Protection, Republic of Moldova, 2021. http://dx.doi.org/10.53040/gppb7.2021.92.
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To determine the complex of fungi that cause rot on the leaves and needles of tree species in the green spaces of Chisinau, foliage was collected in four sectors of the city. It was determined by microbio-logical methods that the complex of pathogens on the leaves differs little in different sectors. The main leaf rot fungi present on the affected leaves and needles are Alternaria sp., Aspergillus sp., Fusarium sp., Penicillium sp. For the treatment of the green spaces of Chisinau against diseases, it is advisable to carry out phytosanitary measures with biological products.
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Voronkova, A. Kh. "THE DETERMINATION OF THE PHYTOTOXICITY AND GROWTHSTIMULATING ACTIVITY OF PROMISING ANTAGONIST STRAINS OF FUSARIUM BLIGHT PATHOGENS ON THE OIL FLAX CROP." In 11-я Всероссийская конференция молодых учёных и специалистов «Актуальные вопросы биологии, селекции, технологии возделывания и переработки сельскохозяйственных культур». V.S. Pustovoit All-Russian Research Institute of Oil Crops, 2021. http://dx.doi.org/10.25230/conf11-2021-148-152.
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The article presents the test results on determination of the phytotoxicity and growth-promoting activity of the antagonist strains of oil flax Fusarium blight pathogens identified at the first stages of screening from the collection of the biomethod laboratory of V.S. Pustovoit All-Russian Research Institute of Oil Crops. We established that the promising strains of fungi and bacteria do not have a negative effect on the germination of oil flax seeds and do not cause wilting of seedlings. In all variants we observed an increase in seed germination by 5.0–13.0 % in comparison with the control. The bacterial strains К 1-2 B. subtilis and 11-3 Bacillus sp. showed the best results in increasing the root length (by 102.0–108.4 %) and the root mass (by 100 %) compared to the control. Among the fungi strains, T-1 Trichoderma sp. showed an increase in the root length and mass by 55.1 % and 66.7 %, respectively, in comparison with the control. We also noted the effect of all studied strains on the shoot length and mass in comparison with the control but to a lesser extent than on the root (by 2.3–35.7 % and 20.0–62.5 %, respectively).
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Chaerani, Ragapadmi Purnamaningsih, and Suci Rahayu. "Isolation and pathogenicity test of fusarium basal rot and purple blotch fungal pathogens from shallot and Allium spp." In THE SECOND INTERNATIONAL CONFERENCE ON GENETIC RESOURCES AND BIOTECHNOLOGY: Harnessing Technology for Conservation and Sustainable Use of Genetic Resources for Food and Agriculture. AIP Publishing, 2022. http://dx.doi.org/10.1063/5.0075209.
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Datsenko, L. A. "SUNFLOWER DRY ROT (REVIEW)." In 11-я Всероссийская конференция молодых учёных и специалистов «Актуальные вопросы биологии, селекции, технологии возделывания и переработки сельскохозяйственных культур». V.S. Pustovoit All-Russian Research Institute of Oil Crops, 2021. http://dx.doi.org/10.25230/conf11-2021-156-162.
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We carried out analysis of the literature data on the knowledge level of sunflower dry rot in the laboratory of biomethod of the crop management department of V.S. Pustovoit All-Russian Research Institute of Oil Crops (VNIIMK). As a result of the analysis, we studied the following issues: the disease pathogen; symptoms of manifestation; the disease prevalence in the world and in Russia; its harmfulness; biology; species composition and taxonomic position of fungi of the genus Rhizopus on sunflower; methods of artificial infection of sunflower with dry rot.
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Prudnikova, Svetlana. "THE DEVELOPMENT OF SLOW-RELEASED FUNGICIDE PREPARATIONS BASED ON BIODEGRADABLE POLY(3-HYDROXYBUTYRATE) TO SUPPRESS ROOT-ROT PATHOGENIC FUNGI." In 19th SGEM International Multidisciplinary Scientific GeoConference EXPO Proceedings. STEF92 Technology, 2019. http://dx.doi.org/10.5593/sgem2019v/6.3/s08.028.
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Majumdar, Ayanava, Mark A. Boetel, Stefan T. Jaronski, Robert J. Dregseth, and Alan J. Schroeder. "Bio-based management of sugarbeet root maggot by integrating an insect pathogenic fungus and cereal cover crops." In American Society of Sugar Beet Technologist. ASSBT, 2007. http://dx.doi.org/10.5274/assbt.2007.67.
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Maslienko, L. V., A. Kh Voronkova, E. A. Efimtseva, and L. A. Datsenko. "The action mechanism of the promising fungal producer strain of the microbiopreparation M-24 Penicillium sp. on the pathogen of sunflower Phoma rot." In PROCEEDINGS OF THE II INTERNATIONAL CONFERENCE ON ADVANCES IN MATERIALS, SYSTEMS AND TECHNOLOGIES: (CAMSTech-II 2021). AIP Publishing, 2022. http://dx.doi.org/10.1063/5.0093008.
Full textReports on the topic "Fungal root pathogens"
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Cytryn, E., Sean F. Brady, and O. Frenkel. Cutting edge culture independent pipeline for detection of novel anti-fungal plant protection compounds in suppressive soils. Israel: United States-Israel Binational Agricultural Research and Development Fund, 2022. http://dx.doi.org/10.32747/2022.8134142.bard.
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Fusarium oxysporum spp. causes Panama disease in bananas and crown and root rot in an array of vegetables and field crops, but increased regulations have restricted the use of many conventional chemical pesticides, and there are a limited number of commercially available products effective against them. The soil microbiome represents a largely untapped reservoir of secondary metabolites that can potentially antagonize fungal pathogens. However, most soil bacteria cannot be cultivated using conventional techniques and therefore most of these compounds remain unexplored. The overall goal of this two-year project was to extract and characterize novel secondary metabolites from "unculturable" soil microbiomes that antagonize Fusarium and other fungal plant pathogens. Initially, the Cytryn lab at the Volcani Institute (ARO) identified candidate biosynthetic gene clusters (BGCs) encoding for potentially novel antifungal compounds (specifically non-ribosomal peptides and polyketides) in soil and plant root microbiomes using cutting-edge metagenomic platforms. Next, the Brady lab at Rockefeller University (RU) screened archived soil metagenomic cosmid libraries for these BGCs, and heterologously expressed them in suitable hosts. Finally, the Frenkel and Cytryn labs at ARO assessed the capacity of these heterologous expressed strains to antagonize Fusarium and other fungal plant pathogens. Initially tomato and lettuce were analyzed, and subsequently roots of cucumbers grown in suppressive (biochar amended) soils were targeted. We found that the composition of tomato and lettuce root BGCs are similar to each other, but significantly different from adjacent bulk soil, indicating that root bacteria possess specific secondary metabolites that are potentially associated with rhizosphere competence. BGC linked to known metabolites included various antimicrobial, (e.g., streptazone E, sessilin), antifungal (heat-stable antifungal factor- HSAF, II and ECO-02301), and insecticidal (melingmycin, orfamide A) compounds. However, over 90% of the identified BGCs were moderately to significantly different from those encoding for characterized secondary metabolites, highlighting the profusion of potentially novel secondary metabolites in both root and soil environments. Novel BGCs that were abundant in roots and remotely resembled those of antifungal compounds were transferred to RU for subsequent screening and five were identified in RU soil metagenomic cosmid libraries. Two of these clusters (BARD-1711 BARD-B481) were heterologously-expressed in a Streptomyces albus J1074 strain, and transferred to ARO. The strain harboring BARAD-B481 was found to antagonize Fusarium significantly more than the host strain, indicating that this BGCs product has antifungal activity. Future studies will need to work on chemically characterizing the BARAD-B481 BGC and progress with the above described pipeline for other interesting BGCs.
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Cytryn, Eddie, Mark R. Liles, and Omer Frenkel. Mining multidrug-resistant desert soil bacteria for biocontrol activity and biologically-active compounds. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7598174.bard.
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Control of agro-associated pathogens is becoming increasingly difficult due to increased resistance and mounting restrictions on chemical pesticides and antibiotics. Likewise, in veterinary and human environments, there is increasing resistance of pathogens to currently available antibiotics requiring discovery of novel antibiotic compounds. These drawbacks necessitate discovery and application of microorganisms that can be used as biocontrol agents (BCAs) and the isolation of novel biologically-active compounds. This highly-synergistic one year project implemented an innovative pipeline aimed at detecting BCAs and associated biologically-active compounds, which included: (A) isolation of multidrug-resistant desert soil bacteria and root-associated bacteria from medicinal plants; (B) invitro screening of bacterial isolates against known plant, animal and human pathogens; (C) nextgeneration sequencing of isolates that displayed antagonistic activity against at least one of the model pathogens and (D) in-planta screening of promising BCAs in a model bean-Sclerotiumrolfsii system. The BCA genome data were examined for presence of: i) secondary metabolite encoding genes potentially linked to the anti-pathogenic activity of the isolates; and ii) rhizosphere competence-associated genes, associated with the capacity of microorganisms to successfully inhabit plant roots, and a prerequisite for the success of a soil amended BCA. Altogether, 56 phylogenetically-diverse isolates with bioactivity against bacterial, oomycete and fungal plant pathogens were identified. These strains were sent to Auburn University where bioassays against a panel of animal and human pathogens (including multi-drug resistant pathogenic strains such as A. baumannii 3806) were conducted. Nineteen isolates that showed substantial antagonistic activity against at least one of the screened pathogens were sequenced, assembled and subjected to bioinformatics analyses aimed at identifying secondary metabolite-encoding and rhizosphere competence-associated genes. The genome size of the bacteria ranged from 3.77 to 9.85 Mbp. All of the genomes were characterized by a plethora of secondary metabolite encoding genes including non-ribosomal peptide synthase, polyketidesynthases, lantipeptides, bacteriocins, terpenes and siderophores. While some of these genes were highly similar to documented genes, many were unique and therefore may encode for novel antagonistic compounds. Comparative genomic analysis of root-associated isolates with similar strains not isolated from root environments revealed genes encoding for several rhizospherecompetence- associated traits including urea utilization, chitin degradation, plant cell polymerdegradation, biofilm formation, mechanisms for iron, phosphorus and sulfur acquisition and antibiotic resistance. Our labs are currently writing a continuation of this feasibility study that proposes a unique pipeline for the detection of BCAs and biopesticides that can be used against phytopathogens. It will combine i) metabolomic screening of strains from our collection that contain unique secondary metabolite-encoding genes, in order to isolate novel antimicrobial compounds; ii) model plant-based experiments to assess the antagonistic capacities of selected BCAs toward selected phytopathogens; and iii) an innovative next-generation-sequencing based method to monitor the relative abundance and distribution of selected BCAs in field experiments in order to assess their persistence in natural agro-environments. We believe that this integrated approach will enable development of novel strains and compounds that can be used in large-scale operations.
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MacDonald, James D., Aharon Abeliovich, Manuel C. Lagunas-Solar, David Faiman, and John Kabshima. Treatment of Irrigation Effluent Water to Reduce Nitrogenous Contaminants and Plant Pathogens. United States Department of Agriculture, July 1993. http://dx.doi.org/10.32747/1993.7568092.bard.
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The contamination of surface and subterranean drinking water supplies with nitrogen-laden agricultural wastewater is a problem of increasing concern in the U.S. and Israel. Through this research, we found that bacteria could utilize common organic wastes (e.g. paper, straw, cotton) as carbon sources under anaerobic conditions, and reduce nitrate concentrations in wastewater to safe levels. Two species of bacteria, Cellulomonas uda and a Comamonas sp., were required for dentitrification. Celulomonas uda degraded cellulose and reduced nitrate to nitrite. In addition, it excreted soluble organic carbon needed as a food source by the Comamonas sp. for completion of denitrification. We also found that recirculated irrigation water contains substantial amounts of fungal inoculum, and that irrigating healthy plants with such water leads to significant levels of root infection. Water can be disinfected with UV, but our experiments showed that Hg-vapor lamps do not possess sufficient energy to kill spores in wastewater containing dissolved organics. Excimer lasers and Xenon flashlamps do possess the needed power levels, but only the laser had a high enough repetition rate to reliably treat large volumes of water. Ozone was highly efficacious, but it's use as a water treatment is probably best suited to moderate or low volume irrigation systems. This research provides critical data needed for the design of effective water denitrification and/or pathogen disinfection systems for different growing operations.
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Harman, Gary E., and Ilan Chet. Enhancement of plant disease resistance and productivity through use of root symbiotic fungi. United States Department of Agriculture, July 2008. http://dx.doi.org/10.32747/2008.7695588.bard.
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The objectives of the project were to (a) compare effects ofT22 and T-203 on growth promotion and induced resistance of maize inbred line Mol7; (b) follow induced resistance of pathogenesis-related proteins through changes in gene expression with a root and foliar pathogen in the presence or absence of T22 or T-203 and (c) to follow changes in the proteome of Mol? over time in roots and leaves in the presence or absence of T22 or T-203. The research built changes in our concepts regarding the effects of Trichoderma on plants; we hypothesized that there would be major changes in the physiology of plants and these would be reflected in changes in the plant proteome as a consequence of root infection by Trichoderma spp. Further, Trichoderma spp. differ in their effects on plants and these changes are largely a consequence of the production of different elicitors of elicitor mixtures that are produced in the zone of communication that is established by root infection by Trichoderma spp. In this work, we demonstrated that both T22 and T-203 increase growth and induce resistance to pathogens in maize. In Israel, it was shown that a hydrophobin is critical for root colonization by Trichoderma strains, and that peptaibols and an expansin-like protein from Ttrichoderma probably act as elicitors of induced resistance in plants. Further, this fungus induces the jasmonate/ethylene pathway of disease resistance and a specific cucumber MAPK is required for transduction of the resistance signal. This is the first such gene known to be induced by fungal systems. In the USA, extensive proteomic analyses of maize demonstrated a number of proteins are differentially regulated by T. harzianum strain T22. The pattern of up-regulation strongly supports the contention that this fungus induces increases in plant disease resistance, respiratory rates and photosynthesis. These are all very consistent with the observations of effects of the fungus on plants in the greenhouse and field. In addition, the chitinolytic complex of maize was examined. The numbers of maize genes encoding these enzymes was increased about 3-fold and their locations on maize chromosomes determined by sequence identification in specific BAC libraries on the web. One of the chitinolytic enzymes was determined to be a heterodimer between a specific exochitinase and different endochitinases dependent upon tissue differences (shoot or root) and the presence or absence of T. harzianum. These heterodimers, which were discovered in this work, are very strongly antifungal, especially the one from shoots in the presence of the biocontrol fungus. Finally, RNA was isolated from plants at Cornell and sent to Israel for transcriptome assessment using Affymetrix chips (the chips became available for maize at the end of the project). The data was sent back to Cornell for bioinformatic analyses and found, in large sense, to be consistent with the proteomic data. The final assessment of this data is just now possible since the full annotation of the sequences in the maize Affy chips is just now available. This work is already being used to discover more effective strains of Trichoderma. It also is expected to elucidate how we may be able to manipulate and breed plants for greater disease resistance, enhanced growth and yield and similar goals. This will be possible since the changes in gene and protein expression that lead to better plant performance can be elucidated by following changes induced by Trichoderma strains. The work was in, some parts, collaborative but in others, most specifically transcriptome analyses, fully synergistic.
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Kistler, Harold Corby, and Talma Katan. Identification of DNA Unique to the Tomato Fusarium Wilt and Crown Rot Pathogens. United States Department of Agriculture, September 1995. http://dx.doi.org/10.32747/1995.7571359.bard.
Full textAbstract:
Wilt and crown rot are two important diseases of tomato caused by different strains ("formae speciales") of the fungus, Fusarium oxysporum. While both pathogens are members of the same fungal species, each differs genetically and resistance to the diseases is controlled by different genes in the plant. Additionally, the formae speciales differ in their ecology (e.g. optimal temperature of disease development) and epidemiology. Nevertheless, the distinction between these diseases based on symptoms alone may be unclear due to overlapping symptomatology. We have found in our research that the ambiguity of the pathogens is further confounded because strains causing tomato wilt or crown rot each may belong to several genetically and phylogenetically distinct lineages of F. oxysporum. Furthermore, individual lineages of the pathogen causing wilt or crown rot may themselves be very closely related. The diseases share the characteristic that the pathogen's inoculum may be aerially dispersed. This work has revealed a complex evolutionary relationship among lineages of the pathogens that makes development of molecular diagnostic methods more difficult than originally anticipated. However, the degree of diversity found in these soil-borne pathogens has allowed study of their population genetics and patterns of dispersal in agricultural settings.
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Prusky, Dov, Lisa Vaillancourt, and Robert Fluhr. Host Ammonification by Postharvest Pathogens and its Contribution to Fungal Colonization and Symptom Development. United States Department of Agriculture, December 2006. http://dx.doi.org/10.32747/2006.7592640.bard.
Full textAbstract:
Postharvest decay of fruits and vegetables caused by pathogenic and saprophytic fungi significantly impairs the quality and quantity of fresh produce brought to market. Consequently, there is considerable interest in identifying factors that determine the susceptibility of these commodities to pathogen infection. Insidious postharvest decays remain quiescent during fruit growth and harvest, but activate during the postharvest period. A key response to the physiological changes occurring during fruit ripening is the initiation of ammonium secretion by the pathogen. Ammonium ions at the infection site (ammonification) have subsequent effects on both the pathogen and the host. An accompanying alkalinization process resulting from ammonia accumulation contributes to pathogenicity, since some important fungal virulence factors, (such as pectate lyase in Colletotrichum sp.), are significantly expressed only under alkaline conditions. In this proposal, investigated the mechanisms by which ammonification and alkalinization of infected tissues by the pathogen affect the host’s defense response to fungal attack, and instead increase compatibility during postharvest pathogen-host interactions. Our hypotheses were:1) that host signals, including ripening-related changes, induce secretion of ammonia by the pathogen; 2) that ammonia accumulation, and the resultant environmental alkalinization regulate the expression of fungal virulence genes that are essential for postharvest rot development; 3) that ammonification enhanced fungal colonization, by “suppression of host responses”, including production of reactive oxygen species, activation of superoxide, and polyphenol oxidase production. Our objectives were: to analyze: 1) factor(s) which activate the production and secretion of ammonia by the fungus; 2) fungal gene(s) that play role(s) in the ammonification process; 3) the relationship between ammonification and the activation of host defense response(s) during pathogen colonization; and 4) analyze hostgene expression in alkalinized regions of fruits attacked by hemibiotrophic fungi.
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Katan, Jaacov, and Michael E. Stanghellini. Clinical (Major) and Subclinical (Minor) Root-Infecting Pathogens in Plant Growth Substrates, and Integrated Strategies for their Control. United States Department of Agriculture, October 1993. http://dx.doi.org/10.32747/1993.7568089.bard.
Full textAbstract:
In intensive agriculture, harmful soilborne biotic agents, cause severe damage. These include both typical soilborne (clinical) major pathogens which destroy plants (e.g. Fusarium and Phytophthora pathogens), and subclinical ("minor") pathogens (e.g. Olpidium and Pythium). The latter cause growth retardation and yield decline. The objectives of this study were: (1) To study the behavior of clinical (major) and subclinical (minor) pathogens in plant growth substrate, with emphasis on zoosporic fungi, such as Pythium, Olipidium and Polymyxa. (2) To study the interaction between subclinical pathogens and plants, and those aspects of Pythium biology which are relevant to these systems. (3) To adopt a holistic-integrated approach for control that includes both eradicative and protective measures, based on a knowledge of the pathogens' biology. Zoospores were demonstrated as the primary, if not the sole propagule, responsible for pathogen spread in a recirculating hydroponic cultural system, as verified with P. aphanidermatum and Phytophthora capsici. P. aphanidermatum, in contrast to Phytophthora capsici, can also spread by hyphae from plant-to-plant. Synthetic surfactants, when added to the recirculating nutrient solutions provided 100% control of root rot of peppers by these fungi without any detrimental effects on plant growth or yield. A bacterium which produced a biosurfactant was proved as efficacious as synthetic surfactants in the control of zoosporic plant pathogens in the recirculating hydroponic cultural system. The biosurfactant was identified as a rhamnolipid. Olpidium and Polymyxa are widespread and were determined as subclinical pathogens since they cause growth retardation but no plant mortality. Pythium can induce both phenomena and is an occasional subclinical pathogen. Physiological and ultrastructural studies of the interaction between Olpidium and melon plants showed that this pathogen is not destructive but affects root hairs, respiration and plant nutrition. The infected roots constitute an amplified sink competing with the shoots and eventually leading to growth retardation. Space solarization, by solar heating of the greenhouse, is effective in the sanitation of the greenhouse from residual inoculum and should be used as a component in disease management, along with other strategies.
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Bostock, Richard M., Dov Prusky, and Martin Dickman. Redox Climate in Quiescence and Pathogenicity of Postharvest Fungal Pathogens. United States Department of Agriculture, May 2003. http://dx.doi.org/10.32747/2003.7586466.bard.
Full textAbstract:
Monilinia fructicola causes brown rot blossom blight and fruit rot in stone fruits. Immature fruit are highly resistant to brown rot but can become infected. These infections typically remain superficial and quiescent until they become active upon maturation of the fruit. High levels of chlorogenic acid (CGA) and related compounds occur in the peel of immature fruit but these levels decline during ripening. CGA inhibits cutinase expression, a putative virulence factor, with little or no effect on spore germination or hyphal growth. To better understand the regulation of cutinase expression by fruit phenolics, we examined the effect of CGA, caffeic acid (CA) and related compounds on the redox potential of the growth medium and intracellular glutathione (GSH) levels. The presence of CA in the medium initially lowered the electrochemical redox potential of the medium, increased GSH levels and inhibited cutinase expression. Conidia germinated in the presence of CA, CGA, or GSH produced fewer appressoria and had elongated germ tubes compared to the controls. These results suggest that host redox compounds can regulate fungal infectivity. In order to genetically manipulate this fungus, a transformation system using Agrobacterium was developed. The binary transformation vector, pPTGFPH, was constructed from the plasmid pCT74, carrying green fluorescent protein (GFP) driven by the ToxA promoter of Pyrenophora tritici-repentis and hygromycin B phosphotransferase (hph) under control of the trpC promoter of from Aspergillus nidulans, and the binary vector pCB403.2, carrying neomycin phosphotransferase (nptII) between the T-DNA borders. Macroconidia of M. fructicola were coincubated with A. tumefaciens strain LBA 4404(pPTGFPH) on media containing acetosyringone for two days. Hygromycin- and G418-resistant M. fructicola transformants were selected while inhibiting A. tumefaciens with cefotaxime. Transformants expressing GFP fluoresced brightly, and were formed with high efficiency and frequency of T-DNA integration frequency. The use of these transformants for in situ studies on stone fruit tissues is discussed.
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Phillips, Donald, and Yoram Kapulnik. Using Flavonoids to Control in vitro Development of Vesicular Arbuscular Mycorrhizal Fungi. United States Department of Agriculture, January 1995. http://dx.doi.org/10.32747/1995.7613012.bard.
Full textAbstract:
Vesicular-arbuscular mycorrhizal (VAM) fungi and other beneficial rhizosphere microorganisms, such as Rhizobium bacteria, must locate and infect a host plant before either symbiont profits. Although benefits of the VAM association for increased phosphorous uptake have been widely documented, attempts to improve the fungus and to produce agronomically useful amounts of inoculum have failed due to a lack of in vitro production methods. This project was designed to extend our prior observation that the alfalfa flavonoid quercetin promoted spore germination and hyphal growth of VAM fungi in the absence of a host plant. On the Israeli side of the project, a detailed examination of changes in flavonoids and flavonoid-biosynthetic enzymes during the early stages of VAM development in alfalfa found that VAM fungi elicited and then suppressed transcription of a plant gene coding for chalcone isomerase, which normally is associated with pathogenic infections. US workers collaborated in the identification of flavonoid compounds that appeared during VAM development. On the US side, an in vitro system for testing the effects of plant compounds on fungal spore germination and hyphal growth was developed for use, and intensive analyses of natural products released from alfalfa seedlings grown in the presence and absence of microorganisms were conducted. Two betaines, trigonelline and stachydrine, were identified as being released from alfalfa seeds in much higher concentrations than flavonoids, and these compounds functioned as transcriptional signals to another alfalfa microsymbiont, Rhizobium meliloti. However, these betaines had no effect on VAM spore germination or hyphal growth i vitro. Experiments showed that symbiotic bacteria elicited exudation of the isoflavonoids medicarpin and coumestrol from legume roots, but neither compound promoted growth or germination of VAM fungi in vitro. Attempts to look directly in alfalfa rhizosphere soil for microbiologically active plant products measured a gradient of nod-gene-inducing activity in R. meliloti, but no novel compounds were identified for testing in the VAM fungal system in vitro. Israeli field experiments on agricultural applications of VAM were very successful and developed methods for using VAM to overcome stunting in peanuts and garlic grown in Israel. In addition, deleterious effects of soil solarization on growth of onion, carrot and wheat were linked to effects on VAM fungi. A collaborative combination of basic and applied approaches toward enhancing the agronomic benefits of VAM asociations produced new knowledge on symbiotic biology and successful methods for using VAM inocula under field conditions
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Harman, Gary E., and Ilan Chet. Enhancing Crop Yield through Colonization of the Rhizosphere with Beneficial Microbes. United States Department of Agriculture, December 2001. http://dx.doi.org/10.32747/2001.7580684.bard.
Full textAbstract:
At the start of this project, fungi in the genus Trichoderma were known to be potent biocontrol agents, and their primary mechanism was considered to via direct effects upon the target fungi. Due in large part to the efforts of the two PIs, we now know that this view is far too limited; while Trichoderma spp. do indeed have direct effects on pathogenic fungi, they have very far reaching effects directly upon plants. Indeed, these fungi must be considered as opportunistic plant symbionts; they provide a number of benefits to plants and themselves are favored by large numbers of healthy roots. Research under this BARD grant has demonstrated that These fungi induce resistance mechanisms in plants. They increase root development and depth of rooting; Bradyrhizobium enhances this effect in soybean. They enhance uptake of plant nutrients. They have abilities to solubilize nutrients, such as oxidized metals and insoluble phosphorus compounds by a variety of different mechanisms and biochemicals. This is a marked expansion of our knowledge of the abilities of these organisms. This knowledge has direct implications for understanding of basic plant responses and abilities, and already is being used to improve plant productivity and reduce pollution of the environment.