Download or read book Pathogen Specialization in Root Resistance in Soybean to Phytophthora Rot written by Hazel Avinell Joseph and published by . This book was released on 1991 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Races of the Pathogen Phytophthora Sojae Found in Michigan and Factors Affecting Root Rot of Soybean written by Richard Chemjor Kaitany and published by . This book was released on 2000 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Study of Incomplete Resistance to Phytophthora Sojae in Soybean written by Santiago Xavier Mideros Mora and published by . This book was released on 2006 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Phytophthora root and stem rot caused by Phytophthora sojae, is a serious limitation to soybean production in the United States. Extensive deployment of Rps genes in soybean cultivars has led to adaptations in the P. sojae populations. Partial resistance to P. sojae in soybeans is effective against all races of the pathogen and is a form of incomplete resistance where the plant reduces the rate of colonization of the pathogen. In addition to partial resistance other types of incomplete resistance have also been described. Rps2 is a single dominant gene that confers incomplete resistance in soybean hypocotyls. Root resistance, thought to be quantitatively inherited, is another form of race specific resistance that appears to function only in the roots. In order to differentiate partial resistance from the other types of incomplete resistance that are race specific, components of resistance were analyzed and the cytology of infection compared. For this study attempts to genetically transform P. sojae to express a marker gene were unsuccessful. Three components were measured (lesion length, oospore production and infection frequency) in 8 soybean genotypes that were inoculated with non-transformed P. sojae isolates on the roots. Light and epifluorescent microscopy were used to study transversal cuts of Trypan blue stained root samples that were also inoculated with P. sojae. Soybean partial resistance was found to be composed of various components that interact to produce the partial resistance phenotype for defense against P. sojae in the roots. It was also found that the Rps2 and root resistant genotypes had significantly reduced levels for all of the components of resistance studied in comparison to the partially resistant genotype Conrad. However, the high levels of partial resistance in Jack were indistinguishable from the Rps2 reaction for all the components studied. In the cytology study it was found that P. sojae penetrates into all the soybean incomplete resistant genotypes: partial resistant, Rps2, and root resistant. Several mechanisms of resistance were observed: i) the resistance phenotype (Rpsla) contained the pathogen biotrophic growth from between 0 to 24 hal in a hypersensitive response; ii) Rps2 and root resistance phenotypes, also stopped growth of the pathogen but this occurred between 24 and 48 hal in a delayed hypersensitive response and iii) the partial resistance and the susceptible phenotypes allowed biotrophic colonization ofF. sojae. Finally a methodology to differentiate among mechanisms of incomplete resistance to P. sojae in soybean was identified based on the number of dead cells and extent of colonization that differed in partial resistance and Rps2 phenotypes.

Download or read book Mechanisms of Resistance and Candidate Gene Analysis Towards Fusarium Graminearum and Phytophthora Sojae in Soybean written by Cassidy Renee Gedling and published by . This book was released on 2018 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerous diseases affect soybean [Glycine max (L.) Merr] yields throughout the growing season in Ohio. Two soil borne pathogens Fusarium graminearum and Phytophthora sojae are known to reduce stand and yield. Currently, fungicide seed treatments are used to manage these pathogens, however, host plant resistance is often the best management strategy for field crops. Thus, the overall objective of the five chapters this dissertation was to identify mechanisms and candidate genes of resistance that are effective towards seed, seedling, and root rots caused by Fusarium graminearum and P. sojae in soybean. Quantitative disease resistance loci (QDRL) have been mapped in two separate recombinant inbred line (RIL) populations for resistance to Fusarium graminearum . In the F7:8 RIL derived from a cross Magellan X PI 567516C, one major QDRL was mapped. Fine mapping of this region identified four putative candidate genes for resistance to Fusarium graminearum . In an additional population of Wyandot x PI 567301B, a major and minor QDRL was mapped to chromosome 8 and 6, respectively. Hybrid genome assembly, fine mapping, and RNA sequencing analysis narrowed the major QDRL to 2.5 cM containing three putative candidate genes for resistance or susceptibility. To validate these candidate genes functional analysis needs to be assessed at the seed level. To achieve this we modified the Apple latent spherical virus (ASLV) which allowed for direct inoculation of VIGS-triggering ALSV agro-infiltrated Nicotiana benthamiana leaves onto soybean unifoliates. However, this method is genotype dependent; the virus is detected in numerous reproductive structures including pods, embryos, stems, leaves, and roots. The last objective of this dissertation focuses on mechanisms of partial resistance to Phytophthora sojae . This oomycete is a leading pathogen of soybean, causing root and stem rot (PRR) across the North Central Region in the U.S. Twenty phenotypic quantitative trait loci (pQTL) were previously mapped in a F9:11 Conrad x Sloan recombinant inbred line (RIL) population on chromosomes 1, 4, 9, 15, 16, 18, and 19; however, these regions encompass large portions of the genome. Thus a systems genetics approach that incorporates expression QTL (eQTL) mapping, functional genomics, and gene co-expression analysis was taken to identify molecular mechanisms contributing towards partial resistance, with the specific objective of reducing the list of candidate genes potentially underpinning pQTL. A greater number of eQTL were mapped in inoculated samples relative to mock, indicating transcriptional reprogramming due to P. sojae infection. Of the six co-expression modules identified, three were related to PRR susceptibility driven by three casual hotspots. GO enrichment of casual hotspot GM_17_D indicates that cell wall modification is a putative mechanism for P. sojae resistance. A total of four eQTL and one eQTL hotspots were found to be co-localized with pQTL and identified five candidate genes for resistance.

Download or read book SCREENING FOR RESISTANCE TO PHYTOPHTHORA ROOT ROT IN LUPIN written by Gayathri Udayangika Beligala and published by . This book was released on 2016 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: Phytophthora sojae is a destructive pathogen belonging to the class Oomycota. It has a very narrow host range and infects only soybean and lupin. Infection by P. sojae overcomes most soybean resistance genes. Therefore, lupins can be perceived as a potential reservoir of novel resistance genes that can be engineered into soybean lines. Oomycetes produce motile zoospores that swim towards plant roots and subsequently cause root-rot diseases. This study focuses on determining the chemotactic behaviors of zoospores and pathogenicity of P. sojae race 2 (P6497) towards roots of ten annual lupin (Lupinus spp.) lines and a perennial line (L. perennis). The latter was further divided into three subgroups based on the degree of speckling on the seed coat; darkly speckled, lightly speckled and seeds with no speckles. Root chemotaxis assay showed no statistically significant differences between all the lupin lines tested. For pathogenicity assay, I measured disease incidence and disease severity. Interestingly, two annual lupin lines exhibited resistance to the infection of P. sojae. There was no correlation between chemotaxis of zoospores and disease severity of P. sojae on lupin. This suggests that the attack of zoospores on its host roots does not necessarily lead to root rot symptoms as there is a risk for the pathogen to be recognized by the host receptors which restrict the pathogenic invasion. When chemotactic behaviors of zoospores were tested against the metabolites extracted from lupin seeds exhibiting different seed coat phenotypes, the zoospore attachment was significantly higher towards the metabolites extracted from seed coats of all three seed phenotypes compared to the control with a preferential response to the seed coat extract of dark seeds. It is evident that zoospore attractants possibly isoflavones, are present at higher amount in darkly speckled lupin seeds compared to seeds with no speckles.

Download or read book Characterization of a Major Quantitative Disease Resistance Locus for Partial Resistance to Phytophthora Sojae written by Stephanie Renae Karhoff and published by . This book was released on 2019 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: Phytophthora root and stem rot is caused by the soil-borne oomycete Phytophthora sojae. Host resistance is the main management practice for Phytophthora root and stem rot, and breeders have historically relied on single, major resistance (Rps) genes. However, pathogen populations have adapted to the previously deployed Rps genes. An alternative is to breed for higher levels of partial resistance, which is quantitatively inherited and typically non isolate-specific. Partial resistance is controlled by multiple quantitative disease resistance loci (QDRL). A QDRL explaining up to 45% of the phenotypic variation (PV) was previously identified in plant introduction (PI) 427106 and PI 427105B (QDRL-18). Major QDRL are rare in the soybean – P. sojae pathosystem; thus, near isogenic lines (NILs) contrasting at QDRL-18 were developed and used to test for isolate-specificity, pleiotropic effects, and validate the locus across environments and genetics backgrounds. Resistant introgressions from either PI 427105B or PI 427106 were effective against seven P. sojae isolates of varying pathotype complexity and increased resistance to P. sojae by 11-20% and 35-40% in laboratory and greenhouse assays, respectively. Furthermore, within the NIL set 4060, lines carrying resistant introgression R105B significantly out-yielded lines with the susceptible introgression SOX under highly favorable disease conditions. In order to facilitate future gene cloning and marker-assisted-selection, RNA-Sequencing of a subset of NILs was completed in conjunction with high resolution mapping of this locus. High-resolution mapping of QDRL-18 with 224-233 markers reduced the original 1,852 Kb interval to a 731 Kb region. Within the refined QDRL, seven genes were differentially expressed following inoculation with P. sojae. Of these seven, one gene putatively encoding a receptor-like protein kinase was significantly downregulated in NILs carrying the resistant introgression derived from PI 427105B at all tested time points. The narrowed QDRL-18 region will provide more closely linked markers and prioritizes candidate genes for future functional analyses. Finally, an obstacle to better understanding the genetic mechanisms of quantitative disease resistance is the identification of causal genes underlying resistance loci. Expression quantitative trait loci (eQTL) analysis has emerged as a method for candidate gene identification, but it requires that the population and conditions in which transcript abundance levels and phenotypic values are obtained be the same. Thus, phenotypic quantitative trait loci (pQTL) were identified in a separate mapping population, derived from a cross between `Conrad’ and `Sloan’, to leverage a larger eQTL study aimed at identifying resistance mechanisms. Two suggestive and one significant pQTL were identified on chromosomes 10 and 18. Most notably, a cis-eQTL coincided with pQTL located on chromosome 18 and is associated with the expression of a gene putatively encoding a leucine-rich repeat receptor-like protein kinase. Overall, this work contributes to the ongoing effort to (1) better understand the mechanisms associated with partial resistance to P. sojae and (2) develop soybean cultivars with increased levels of partial resistance.

Download or read book Nature of Resistance of Soybeans to Phytophthora Root and Stem Rot written by William Louis Klarman and published by . This book was released on 1960 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Soybean Diseases written by Denis C. McGee and published by American Phytopathological Society. This book was released on 1992 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Diseases that are seedborne and seed transmitted; Fungi; Ascochyta leaf spot; Anthracnose; Curvularia cotyledon spot; Downy mildew; Frogeye leaf spot; Phomopsis seed decay; Purple seed stain; Sclerotinia stem rot; Bacteria; Bacterial blight; Bacterial pustule; Bacterial tan spot; Bacterial wilt; Corynebacterium wilt; Wildfire; Viruses; Alfalfa mosaic; Bean pod mottle; Brazilian bud blight; Bud blight; Cowpea mild mottle; Cucumber mosaic; Peanut stunt; Peanut stripe; Soybean mild mosaic; Soybean mosaic; Soybean stunt; Tomato ringspot; Diseases that are seedborne but not seed transmitted; Fungi; Altenaria leaf spot; Botrytis stem rot; Brown spot; Brown stem rot; Charcoal rot; Drechslera blight; Fusarium pod and collar rot; Fusarium root rot; Fusarium wilt; Myrothecium leaf spot; Phyllosticta leaf spot; Phytophthora root rot; Pythium root rot; Rhizoctonia aerial blight; Rhizoctonia root rot; Stem canker; Southern blight; Storage rot; Target spot, Thielaviopsis root rot; Verticillium stem rot; Yeast spot; Bacteria; Bacillus seed decay; Chocolate spot; Viruses; Southern bean mosaic; Diseases that are not seedborne or seed transmitted; Fungi; Choanephora leaf blight; Leptosphaerulina leaf spot; Mycoleptodiscus root rot; Neocosmospora stem rot; Powdery mildew; Red crown rot; Red leaf blotch; Scab; Soybean rust; Stemphylium leaf blight; Sudden death syndrome; Bacteria; Bacterial crinkle leaf spot; Pseudomonas andropogonis leaf spot; Mycoplasmas; Bud proliferation; Machismo; Witches' broom; Viruses; Abutilion mosaic; African soybean dwarf; Azuki mosaic; bean chlorotic ringspot; Bean common mosaic; Bean yellow mosaic; Black gram mottle; Blackeye cowpea mosaic; Cowpea aphid-borne mosaic; Cowpea chlorotic mottle; Cowpea mosaic; Cowpea severe mosaic; Crinkle leaf; Indonesian soybean dwarf; Mung bean yellow mosaic; Peanut mottle; Rhyncosia mosaic; Rosette; Soybean chlorotic mottle; Soybean dwraf; Soybean severe stunt; Soybean yellow vein; Tobacco mosaic; Tomato spotted wilt.

Download or read book Linkage Relations Between Resistance to Phytophthora Root Rot and Plant and Seed Characteristics in the Soybean written by Md. Fazlul Haque and published by . This book was released on 1962 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Agronomic and Molecular Marker Mapping of Brown Stem Rot Phytophthora Root Rot and Powdery Mildew Resistance in Soybean written by David Glenn Lohnes and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Diseases are a major factor limiting the yield of soybean (Glycine max (L.) Merr.). Brown stem rot of soybean, caused by Phialophora gregata (Allington and Chamberlain) W. Gams, and phytophthora root rot, caused by Phytophthora sojae Kaufmann & Gerdemann, are major diseases of soybean in Illinois. A gene for resistance to powdery mildew, caused by Microsphaera diffusa Cke. & Pk., has also been found to be linked to a gene for phytophthora resistance. A field study was conducted to determine yield differences between isolines carrying different alleles at the locus for powdery mildew resistance, greenhouse experiments were performed to study the inheritance of brown stem rot resistance, and laboratory experiments were conducted in attempts to find molecular markers linked to brown stem rot, phytophthora, and powdery mildew resistance in soybean. When isolines carrying alleles for powdery mildew resistance are compared, the resistant isolines yielded 7% more than the adult-plant resistant isolines. With this yield advantage, it would be advantageous to use complete resistance to powdery mildew as a marker to select for phytophthora resistance in a soybean breeding program. Classification of reaction to brown stem rot of soybean populations indicates that a Clark isoline contains Rbs3, and that a germplasm line deriving resistance from PI 90.138 contains Rbs1 and another unknown resistance gene. Molecular marker analysis of Harosoy and a Harosoy brown stem rot isoline did not produce any polymorphic markers. Clark, Harosoy, and Williams were screened with several RAPD primers to determine the random amplified polymorphic DNA (RAPD) variability present between these cultivars. The percentage of RAPD products in common was 94% for Clark and Williams, 90% for Clark and Harosoy, and 84% for Harosoy and Williams. The material cost of running a single RAPD reaction ranged from 21 to 76 cents. Linkage analysis of the restriction fragment length polymorphism and disease classification revealed that the loci studied are in classical linkage group 19 and RFLP linkage group J, in the most likely order Rps2 Rmd Rj2 pA233 pA724 pK375. This is the most agronomically important gene-dense region of the soybean molecular map identified to date.

Download or read book Inheritance of Virulence in the Root Rot Pathogen Phytophthora Sojae written by Sirjana Devi Shrestha and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The oomycete Phytophthora sojae causes stem and root rot of soybean plants. The interaction of pathogen avirulence (Avr) and host resistance (R)-genes determine the disease outcome. The Avr3a mRNA transcript level is variable among P. sojae strains and determines virulence towards the R-gene Rps3a. To study the inheritance of virulence, genetic crosses and self-fertilizations were performed. A cross between P. sojae strains ACR10 and P7076 causes transgenerational gene silencing of Avr3a allele, and this effect is meiotically stable up to the F5 generation. However, test-crosses of F1 (Avr3aACR10/Avr3aP7076) with strain P6497 result in expression of Avr3a in all progeny and release of silencing of the Avr3aP7076 allele. Progeny from P6497 X ACR10 crosses showed unusual inheritance for Avr3a expression. Overall, we conclude that Avr3a gene silencing is strain specific and could rely on epistatic factors. This study will lead to a better understanding of infection and virulence mechanisms that will help to better manage and safeguard soybean production.

Download or read book Residual Effects of Defeated Resistance Genes on Phytophthora Root Rot of Soybean written by Brian A. Young and published by . This book was released on 1989 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Soybean Phytophthora Root Rot written by Jose Cristino Melgar and published by . This book was released on 1997 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Partial Resistance to Phytophthora Root Rot in Soybean and Association with Tolerance to Saturated Soil Conditions written by William Jay Werk and published by . This book was released on 2005 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Soybean Diseases of the North Central Region written by Thomas D. Wyllie and published by American Phytopathological Society. This book was released on 1988 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides timely information on the major diseases affecting soybeans in the north central soybean growing area of the United States.

Download or read book Genetic Mapping in Experimental Populations written by J. W. Van Ooijen and published by Cambridge University Press. This book was released on 2013-08-08 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: A concise introduction to genetic linkage map construction for biological researchers, combining theory with practical exercises and problem-solving tips.

Download or read book Root Physiology from Gene to Function written by Hans Lambers and published by Springer Science & Business Media. This book was released on 2005-11-28 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Reprinted from Plant and soil, volume 274 (2005)."