Location: Wheat Health, Genetics, and Quality Research
Project Number: 2090-22000-020-002-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Mar 1, 2019
End Date: Feb 29, 2024
Objective:
1. To conduct testing for identifying races and molecular genotypes of the wheat and barley stripe rust pathogens and determine distributions, frequencies, and dynamic changes of races and individual virulence factors of the pathogens in the United States.
2. To conduct experiments and analyses for identifying new sources and new genes of stripe rust resistance, developing molecular markers, and developing improved germplasm of wheat and barley for stripe rust resistance for more efficient use in breeding programs.
3. To participate in wheat and barley germplasm and breeding line screening for resistance to stripe rust and other diseases.
Approach:
1. Stripe rust samples will be collected from commercial fields, breeding nurseries, disease monitoring nurseries, and grasses throughout the Pacific Northwest and received from collaborators in the other regions of the United States. Stripe rust spores will be recovered and increased from samples by inoculating susceptible wheat and/or barley varieties. The isolates will be tested on a set of wheat and/or a set of barley varieties carrying different resistance genes established in the ARS stripe rust program for identifying virulence patterns or races. New races will be identified by analyzing the virulence patterns against previously identified races. Distributions and frequencies will be determined for each state and epidemiological region for the collection of each year. Genomic DNA will be extracted from each isolate and tested with a set of simple sequence repeat (SSR) markers established in the ARS stripe rust germplasm data program. Dynamic changes in races, individual virulence factors, and molecular genotypes will be determined by comparing isolates of different years to understand the mechanisms of stripe rust pathogen population changes. The results will be used for guiding breeding programs to select genes for developing new wheat and barley varieties with effective resistance, and used for managing the diseases based on different types and genes in commercially grown varieties. Genome sequencing and genotyping with other types of markers, such as secreted-protein gene derived single-nucleotide polymorphism (SNP) markers and mating-type gene markers recently developed and identified in the ARS stripe rust program will be used to test selected isolates for identifying important evolutionary events in the pathogen population.
2. Wheat and barley germplasm lines will be selected based on the ARS stripe rust germplasm data. The selected lines will be crossed with susceptible varieties, and mapping populations will be developed from the crosses using either the recombinant inbred approach or doubled haploid approaches. The populations will be tested in the greenhouse with selected races and in multiple field environments to obtain rust phenotypic data and genotyped with SNP chips, SSR markers or genotyping-by-sequencing. The phenotype and genotype data will be used to identify genes controlling stripe rust resistance. From the progeny populations, new germplasm lines with identified resistance genes and improved agronomic traits will be selected and registered as new germplasm for breeding programs to use. Specific crosses will be made and new lines with different resistance genes on same chromosome arms will be selected from the progeny populations for more efficient use in breeding programs.
3. The research associate and part-time workers will be participating in the field and greenhouse germplasm screening project. Working together with colleagues, they will help in preparing seeds, planting in fields and greenhouses, recording disease notes, and harvesting.
