High density mapping of durable and broad-spectrum stripe rust resistance gene Yr30 in wheat

Abstract

Stripe rust is a global fungal disease that is a serious threat to wheat. Durable resistance is the most effective method of control. Yr30, an adult plant resistance (APR) gene with broad-spectrum effectiveness, was located in the putatively pleiotropic locus or QTL that harbors genes Sr2, Lr27, Pm70, Sb3 and Pbc1. Although the locus has been widely deployed worldwide to achieve durable resistance for over a centenary little is known about the genetic relationship and causal genes because of the effects are small and inconstant in different genetic backgrounds and environments. In this study, we identified a residual heterozygous line (RHL), YM91, derived from Yaco"S"/Mingxian169 F5:6 RIL population, where Yr30 was present alone, resistance was identified as dominant and clearly distinguishable. Through selection of heterozygous plants in YM91, a large mapping population was developed. Yr30 was fine-mapped to a 0.52-cM interval between KASP markers AX-109525141 and YM3B-7 corresponding to a physical distance of 610 kb on chromosome 3BS. A candidate gene TraesCS3B03G0028100 encoding tetratricopeptide repeat protein was identified for Yr30 from 30 high-confidence genes within the interval based on the expression level and sequence variation in whole genome RNA-seq data of cultivars with or without Yr30. Six haplotypes (Hap1-6) were identified among 1,215 wheat accessions based on the 660K array and Yr30-haplotype Hap6 conferred equal or higher resistance than the other five haplotypes. These results will accelerate map-based cloning and molecular-assisted selection of Yr30, a likely source of durable resistance.