Identification of adult plant yellow rust resistance QTLs in Jiangsu wheat varieties Ningmai 9 and Yangmai 158

Wheat yellow rust (YR) is a most devastating disease in wheat worldwide. In recent years, the epidemic in China has expanded from traditional areas to the middle and lower reaches of the Yangtze River due to the changes in climate and cropping systems. To facilitate YR resistance breeding, it is meaningful to explore resistance loci from local germplasm resources. In this study, a linkage mapping was performed in a recombinant inbred line (RIL) population derived from Ningmai 9 x Yangmai 158 using a high-density genetic map and phenotypic identification for adult plant resistance (APR) to YR in four environments. Phenotypic analysis showed that Yangmai 158 had better APR than Ningmai 9. Disease severity in different environments was significantly correlated with each other, and it was found that disease severity was significantly influenced by genotype, environment and their interaction. A total of 19 quantitative trait loci (QTLs) were identified, of which four could be detected in multiple environments and four corresponding KASP markers were then developed. Lines with different QTLs from the population including 476 chromosome segment substitution lines (CSSLs) were evaluated for APR. The results revealed that Qyr-4B.4 and Qyr-5B.2 could significantly reduce the disease severity, with their combination showing a better effect. The findings of the study can be beneficial for wheat YR resistance breeding in the middle and lower reaches of the Yangtze River.