Genome-Wide Association Study and Gene Specific Markers Identified 51 Genes or QTL for Resistance to Stripe Rust in U.S. Winter Wheat Cultivars and Breeding Lines.

Jingmei Mu,Xianming Chen,Deven R See,Yan Liu,Meinan Wang,Lu Liu,Dejun Han

doi:10.3389/fpls.2020.00998

Abstract

Stripe (yellow) rust, caused by fungal pathogen Puccinia striiformis f. sp. tritici (Pst), is a serious disease of wheat in the United States and many other countries. Growing resistant cultivars has been approved to be the best approach for control of stripe rust. To determine stripe rust resistance genes in U.S. winter wheat cultivars and breeding lines, we analyzed a winter wheat panel of 857 cultivars and breeding lines in a genome-wide association study (GWAS) using genotyping by multiplexed sequencing (GMS) and by genotyping with molecular markers of 18 important stripe rust resistance genes or quantitative trait loci (QTL). The accessions were phenotyped for stripe rust response at adult-plant stage under natural infection in Pullman and Mount Vernon, Washington in 2018 and 2019, and in the seedling stage with six predominant or most virulent races of Pst. A total of 51 loci were identified to be related to stripe rust resistance, and at least 10 of them (QYrww.wgp.1D-3, QYrww.wgp.2B-2, QYrww.wgp.2B-3, QYrww.wgp.2B-4, QYrww.wgp.3A, QYrww.wgp.5A, QYrww.wgp.5B, QYrww.wgp.5D, QYrww.wgp.6A-2 and QYrww.wgp.7B-3) were previously reported. These genes or QTL were found to be present at different frequencies in breeding lines and cultivars developed by breeding programs in various winter wheat growing regions. Both Yr5 and Yr15, which are highly resistant to all races identified thus far in the U.S., as well as Yr46 providing resistance to many races, were found absent in the breeding lines and commercially grown cultivars. The identified genes or QTL and their markers are useful in breeding programs to improve the level and durability of resistance to stripe rust.

Highlights

Stripe rust, caused by Puccinia striiformis Westend. f. sp. tritici Erikss. (Pst), is one of the most serious diseases threating wheat production in the world (Wellings, 2011; Ellis et al, 2014; Chen, 2020)
Using genotyping by multiplexed sequencing (GMS)-genome-wide association study (GWAS), we identified 35 significantly associated stripe rust resistance loci including 15 loci associated with All-stage resistance (ASR) and 20 associated with adult-plant resistance (APR)
Using the combination of testing previously known genes and GMS-GWAS, we detected a total of 51 loci for stripe rust resistance in the panel of 857 winter wheat accessions including genetic stocks, breeding lines and cultivars used and developed in the U.S These genes or quantitative trait loci (QTL) confer either racespecific ASR or race nonspecific APR

Summary

Introduction

Stripe rust (yellow rust), caused by Puccinia striiformis Westend. f. sp. tritici Erikss. (Pst), is one of the most serious diseases threating wheat production in the world (Wellings, 2011; Ellis et al, 2014; Chen, 2020). Two types of resistance to stripe rust have been characterized and used in breeding programs. All-stage resistance (ASR), which can be detected in the seedling stage, is highly effective in all growth stages and easy to be phenotypically selected in breeding programs, but usually not durable as it can be circumvented by new virulent race of Pst. In contrast, adult-plant resistance (APR) expresses in late plant growth stages and the resistance level is often affected by temperature, and often called high-temperature adultplant (HTAP) resistance. APR or HTAP resistance is durable as it is usually not influenced much by Pst race changes (Chen, 2005; Chen, 2013). The best strategy is to combine APR or HTAP resistance with effective ASR to improve both level and durability of resistance

Objectives

Methods

Results

Discussion

Conclusion