Distribution, frequency and variation of stripe rust resistance Loci Yr10, Lr34/Yr18 and Yr36 in Chinese wheat cultivars.

Wheat stripe rust is a devastating disease in many regions of the world. In wheat, 49 resistance genes for stripe rust have been officially documented, but only three genes are cloned, including the race-specific resistance Yr10 candidate gene (Yr10(CG)) and slow-rusting genes Lr34/Yr18 (hereafter designated as Yr18) and Yr36. In this study, we developed gene-specific markers for these genes and used them to screen a collection of 659 wheat accessions, including 485 Chinese cultivars. Thirteen percent and eleven percent of the tested Chinese cultivars were positive for the markers for Yr10(CG) and Yr18(RH) (the resistant haplotype of Yr18), respectively, but none were positive for the Yr36 marker. Since there is a limited use of the Yr10 gene in Chinese wheat, the relatively high frequency of wheat varieties with the Yr10(CG) marker suggests that the identity of the Yr10 gene is unknown. With regards to the Yr18 gene, 29% of the tested cultivars that are used in the Middle and Lower Yangtze Valleys' winter wheat zone were positive for Yr18(RH) markers. A non-functional allele of Yr18(RH) was identified in 'Mingxian 169', a commonly used susceptible check for studying stripe rust. The data presented here will provide useful information for marker-assisted selection for wheat stripe rust resistance.