Dissertation
DEVELOPMENT OF HOST AND PATHOGEN MUTANTS FOR CHARACTERIZATION OF WHEAT-PUCCINIA STRIIFORMIS F. SP. TRITICI INTERACTIONS USING ETHYL METHANESULFONATE
Doctor of Philosophy (PhD), Washington State University
01/2020
Handle:
https://hdl.handle.net/2376/110844
Abstract
Wheat stripe rust, caused by Puccinia striiformis. f. sp. tritici (Pst), is a devastating disease threatening wheat production across the world. To understand mechanisms of Pst infection and host resistance against stripe rust, mutagenesis studies were conducted using ethyl methanesulfonate (EMS) on both Pst and wheat genotype AvSYr17NIL to identify avirulence candidate genes in the pathogen and resistance genes in wheat. Thirty-three Pst mutants were obtained from EMS mutagenesis of wild-type isolate 11-281. Characterization of the mutants through virulence and molecular marker tests showed that EMS mutagenesis generated diverse races and genotypes with multiple point mutations and extensive intragenic insertions and deletions. The wild-type isolate was sequenced using the Illumina and PacBio technologies. The sequences were assembled into a draft genome with the size of 84.75 Mb and 60.09 Mb for primary scaffolds and haplotigs, respectively, and 16,869 and 12,145 protein-coding genes were annotated, respectively. After aligning with the reference genome with 30 mutant isolates, identifying variant alleles and performing a genome-wide association study, 62 genes were identified as avirulence candidates, of which eight secreted protein genes were identified as putative avirulence genes of high-confidence based on evaluation using six criteria. To test the hypothesis that the wheat near-isogenic line (NIL) AvSYr17NIL for race-specific all-stage resistance gene Yr17 also has a gene for non-race specific high-temperature adult-plant (HTAP) resistance, AvSYr17NIL was mutated using EMS and mutant lines were selected for possessing only HTAP resistance. After crossing selected mutant line M1225 with recurrent parent AvS, a recessive gene, yrM1225, for HTAP resistance was mapped to an interval of 8.97cM on chromosome 2AS. In summary, EMS mutagenesis was an efficient approach in studying Pst avirulence genes and wheat stripe resistance genes. Using EMS mutagenesis, avirulence candidate genes and a HTAP resistance gene were identified. These findings have improved our understanding of a major evolutionary mechanism of the stripe rust pathogen and different types of host resistance. The genomic and genetic resources developed in these studies should be useful for further studies to clone avirulence genes for monitoring the pathogen populations and improve resistance to stripe rust.
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Details
- Title
- DEVELOPMENT OF HOST AND PATHOGEN MUTANTS FOR CHARACTERIZATION OF WHEAT-PUCCINIA STRIIFORMIS F. SP. TRITICI INTERACTIONS USING ETHYL METHANESULFONATE
- Creators
- Yuxiang Li
- Contributors
- Xianming Chen (Advisor)Deven R See (Committee Member)Timothy D Murray (Committee Member)Weidong Chen (Committee Member)Lori M Carris (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Plant Pathology, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 235
- Identifiers
- 99900581498901842
- Language
- English
- Resource Type
- Dissertation