Author: Mallorie Lewarne Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Of the fungal diseases that can infect bread wheat (Triticum aestivum L.), leaf rust, caused by Puccinia triticina Eriks. is the most common and widespread. Pyramiding multiple resistance genes in a cultivar using conventional breeding techniques is often expensive and time consuming. Alternatively, marker assisted selection (MAS) allows for accelerated and accurate selection of resistance gene combinations. The objectives of this study were to characterize two leaf rust resistance genes: an adult plant resistance (APR) gene, hypothesized to be Lr46, from wheat line BW278, and a seedling resistance gene, Lr2a, from wheat cultivar Superb. To characterize the APR, two mapping populations derived from BW278 were genotyped with the iSelect 90K wheat SNP array. Both populations were evaluated for leaf rust in inoculated field nurseries for five years. Quantitative trait locus (QTL) analysis revealed two QTL controlling resistance in the BW278/AC Foremost population, one in the region of interest, chromosome 1B and another on chromosome 5A. Two QTL were detected in Superb/BW278, on chromosomes 4B and 5B, however no QTL were detected in the region of interest on 1B. The QTL on 1B in BW278/AC Foremost, designated QLr.mrdc-1B, was tightly linked to both csLV46G22 and DK0900, two markers previously described as tightly linked to the Lr46 locus. Ten SNPs in the QLr.mrdc-1B region were selected for kompetitive allele-specific PCR (KASP) assay design. To characterize Lr2a, two mapping populations derived from Superb (Superb/BW278 & Superb/86ISMN 2137) were genotyped with the iSelect 90 K wheat SNP array, and evaluated with a single race of P. triticina under greenhouse conditions. Two-point linkage analysis between the marker data and phenotypic infection type ratings revealed that the gene mapped to chromosome 2DS in both mapping populations. The linkage maps generated for the two mapping populations had 11 SNP markers in common and displayed collinearity. Seven SNPs that either flanked or co-segregated with Lr2a in Superb/BW278 were selected for KASP assay design. Of the seven markers, kwh740 (Excalibur_c1944_1017) was polymorphic in both populations and displayed clear clusters, making it the most applicable for use in MAS.
Author: Vanesa Segovia Publisher: ISBN: Category : Languages : en Pages :
Book Description
In Kansas, wheat (Triticum aestivum L.) is severely affected by the biotrophic fungus Puccinia triticina (leaf rust). Although resistant varieties have been developed, the fungus tends to overcome new sources resistance very quickly. Plants have evolved a single gene (R genes) defense network that can recognize specific pathogen effectors (Avr), in a gene-for-gene manor. In rusts, effectors are secreted proteins responsible for inducing the uptake of nutrients and inhibit host defense responses. Identification of secreted proteins during the infection may help to understand the mode of infection of P. triticina. Little is known about molecular interactions in the pathosystem wheat-leaf rust and no Avr genes from cereal rusts have been cloned. In order to understand pathogenicity in leaf rust and generate new alternatives for disease control, the goal of this research is identify P. triticina secreted proteins from a collection of expressed genes during the infection, and to characterize putative Avr function for three candidates. From 432 EST's derived from haustoria and infected plants, fifteen secreted proteins were identified and 10 were selected as potential avirulence candidates. Pt3 and Pt 51 are two P. triticina (Pt) candidates expressed specifically in the haustoria and encode small cysteine-rich secreted proteins. Eight candidates are expressed at early stages of infection, during spore germination and 6 days after inoculation. They are small-secreted proteins. None are repetitive elements or have nuclear localization signals. They also do not share a conserved motif with known filamentous fungus Avr proteins. Five candidates are novel proteins, two have similarity with predicted proteins, one is homologous with Hesp-379-like protein, one is homologous with superoxide dismutase, and one has a cell glucanase predicted function. Pt3, Pt12 and Pt27 were tested by transient expression experiments using co-bombardment with GUS into leaf rust resistant isogenic lines. Reduction in the expression of reporter gene GUS co-expressed with Pt27 indicates a potential avirulence factor for Lr26 in wheat.
Author: RA McIntosh Publisher: CSIRO PUBLISHING ISBN: 0643103023 Category : Technology & Engineering Languages : en Pages : 308
Book Description
Although stem rust has been controlled by means of resistant cultivars, leaf and stripe rust continue as problems for many growing areas of the world. Wheat Rusts: An Atlas of Resistance Genes has been prepared by specialists from one of the leading international laboratories, and illustrates with colour photographs typical resistance phenotypes associated with most known genes for resistance to the three rust diseases of wheat. Relevant details for each gene include chromosome location, aspects of genetics and pathogen variation, the effects of environment on expression, origin, availability in genetic and breeding stocks, and use in agriculture. This atlas includes an introduction to host:pathogen genetics, methodologies for wheat rust research and breeding for resistance.
Author: Arjun Upadhaya Publisher: ISBN: Category : Barley Languages : en Pages : 0
Book Description
Stem rust caused by the biotrophic fungal pathogen Puccinia graminis f. sp. tritici (Pgt) is an important disease of barley and wheat globally. In the last decade, the Pacific Northwest (PNW) region of the United States has experienced an increase in the incidence and severity of stem rust disease. This may be attributed to various factors, including increase in summer temperatures, lack of effective resistance, and early inoculum from sexual hosts. The PNW region's conducive environment and the presence of the sexual hosts, Mahonia and barberry, present an opportunity for the stem rust pathogen to complete its sexual cycle, leading to the emergence of genotypes with novel virulence gene combinations. A total of 100 Pgt isolates collected from barley in eastern Washington during the 2019 growing season were tested for virulence on the two major barley stem rust resistance genes/loci, Rpg1 and the rpg4/5-mediated resistance locus (RMRL) at the seedling stage. Of these isolates, 99% were virulent on cultivar Morex containing the Rpg1 gene, 62% were virulent on Golden Promise transgenic line (H228.2c) carrying a single copy of the Rpg1 gene from Morex, 16% were virulent on the near isogenic line, HQ-1 containing RMRL, and 10% were virulent on barley line Q21861 carrying both Rpg1 and RMRL. This was the first report of Pgt isolates containing virulence on both Rpg1 and RMRL when stacked together, representing the most virulent Pgt population reported on barley worldwide. To identify and map effective resistances against the local virulent isolates, a genome wide association study (GWAS) was conducted on 440 accessions from the World Barley Core Collection (WBCC), genotyped with the 9K Illumina barley iSelect chip and phenotyped with two PNW Pgt isolates at the seedling stage. A total of 10 resistance loci were identified including four novel loci on chromosomes 1H, 2H, 5H, and 6H. On the pathogen side, GWAS was performed using 113 diverse Pgt isolates, collected from the PNW and the Midwest region of the US, to identify virulence and avirulence loci corresponding to the barley stem rust resistance gene Rpg1 and the six wheat stem rust R-genes, Sr5, Sr21, Sr8a, Sr17, Sr9a, and Sr9d. The genotype data for 96 isolates were generated by whole genome shotgun sequencing and for 17 isolates by RNA sequencing. The phenotype data for the Pgt isolates were collected by seedling disease assays on two barley lines, H228.2c and Morex (Rpg1+) and the six wheat stem rust differential lines, Sr5, Sr21, Sr8a, Sr17, Sr9a, and Sr9d. A total of five effector gene candidates were identified at two loci corresponding to the Rpg1 gene. Similarly, 24 putative effector genes were identified at 15 loci corresponding to the six wheat R-genes. Further characterization of these genes will be done to enhance our understanding of host pathogen interactions in both the barley-Pgt and wheat-Pgt pathosystems.
Author: Xianming Chen Publisher: Springer ISBN: 9402411119 Category : Science Languages : en Pages : 723
Book Description
This book comprehensively introduces stripe rust disease, its development and its integral control. Covering the biology, genetics, genome, and functional genomics of the pathogen, it also discusses host and non-host resistance, their interactions and the epidemiology of the disease. It is intended for scientists, postgraduates and undergraduate studying stripe rust, plant pathology, crop breeding, crop protection and agricultural science, but is also a valuable reference book for consultants and administrators in agricultural businesses and education.
Author: Sambasivam Periyannan Publisher: Humana ISBN: 9781493984305 Category : Science Languages : en Pages : 294
Book Description
This volume presents a collection of tools currently used for the characterization of rust, the host plant wheat, and their interactions. This book is divided into five parts: Parts I and II discuss advanced techniques for characterizing rust pathogens in rust surveillance, genotyping, and molecular pathogenicity; Part III describes protocols for genetic analysis of rust resistance; Part IV covers methods on rust resistance gene cloning; and Part V talks about the isolation and screening of bacterial endophytes as biocontrol agents for rust disease management. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Cutting-edge and authoritative, Wheat Rust Disease: Methods and Protocols is a valuable resource for both established and novel wheat rust researchers and also the plant science and microbial research community.
Author: Mallorie Lewarne
Author: Hongwei Wang
Author: Wenhao Li
Author: Vanesa Segovia
Author: RA McIntosh
Author: Colin W. Hiebert
Author: Arjun Upadhaya
Author: 
Author: Xianming Chen
Author: Sambasivam Periyannan