Abstract:

Yellow rust, caused by Puccinia striiformis Westend f. sp. tritici, is one of the most important diseases of wheat (Triticum aestivum L.) worldwide. Breeding for resistance is considered the most economical and effective mean for controlling the disease. Guinong 21, a common wheat cultivar derived from an open pollinated population between common wheat and the F₁ hybrid of Haynaldia villosa and Triticum durum, provided sound resistance to prevalent Chinese races of Puccinia striiformis f. sp. tritici and Blumeria graminis f. sp. tritici for decades. Genetic analysis indicated that Guinong 21 is carrying a single dominant yellow rust resistance gene, designated as YrGn21 temporarily. Segregating F₂ progenies of the cross (Guinong21/704) F₂/Wenmai8 were used for bulked segregation analysis (BSA). Eleven microsatellite markers, Xcau14, Xwmc49, Xgwm403, Xgdm62, Xwmc272, Xgwm459, Xbarc240, Xbarc187, Xgdm28, Xgwm11 and Xgwm413 were found to be linked to YrGn21 and all of them were assigned to the same side of gene YrGn21. The closest marker Xcau14 was mapped 1.1 cM away from the resistant gene and the furthest marker Xgwm413 was located 7.1 cM to YrGn21. Based on the reported genetic and physical maps of microsatellites in wheat, most of these YrGn21 linked markers have been mapped in the adjacent region of centromere on chromosome 1BS. It had been reported that Xgwm11 and Xgwm413 were linked to yellow rust resistance gene Yr26, which was also located on chromosome 1BS. Polymorphisms detected by the 11 YrGn21 linked markers on an Yr26 population indicated that same polymorphic fragments could be amplified by 10 out 11 primers on the resistant plants of YrGn21 and Yr26. It is deduced that YrGn21 might be an allelic locus of Yr26 and the 11 close linked markers to the resistant gene (YrGn21) established in this research would facilitate the marker-assisted selection (MAS) and the pyramiding of YrGn21 in wheat breeding programs.

Key words: Wheat, Guinong 21, Yellow rust resistant gene, Microsatellite marker