Molecular characterization and validation of adult-plant stripe rust resistance gene Yr86 in Chinese wheat cultivar Zhongmai 895.

Key message: Adult-plant stripe rust resistance gene Yr86 in Chinese wheat cultivar Zhongmai 895 was mapped to the physical interval 710.2–713.2 Mb on the long arm of chromosome 2A. Adult-plant resistance to stripe rust is generally more durable than all-stage resistance. Chinese wheat cultivar Zhongmai 895 showed stable stripe rust resistance at the adult-plant stage. To map the genetic loci underlying its resistance, 171 doubled haploid (DH) lines from a Yangmai 16/Zhongmai 895 cross were genotyped with the wheat 660 K SNP chip. Disease severities of the DH population and parents were assessed in four environments. A major QTL designated QYryz.caas-2AL was mapped to interval 703.7–715.3 Mb on the long arm of chromosome 2A using both chip-based and KASP (kompetitive allele-specific PCR) marker-based methods, explaining 31.5 to 54.1% of the phenotypic variances. The QTL was further validated in an F2 population of cross Emai 580/Zhongmai 895 with 459 plants and a panel of 240 wheat cultivars using KASP markers. Three reliable KASP markers predicted a low frequency (7.2–10.5%) of QYryz.caas-2AL in the test panel and remapped the gene to the physical interval 710.2–713.2 Mb. Based on different physical positions or genetic effects from known genes or QTL on chromosome arm 2AL, the gene was predicted to be a new one for adult-plant stripe rust resistance and was named Yr86. Twenty KASP markers linked to Yr86 were developed in this study based on wheat 660 K SNP array and genome re-sequencing. Three of them are significantly associated with stripe rust resistance in natural population. These markers should be useful for marker-assisted selection and also provide a starting point for fine mapping and map-based cloning of the new resistance gene. [ABSTRACT FROM AUTHOR]