Resistance in wild emmer wheat (Triticum dicoccoides) from the fertile crescent to yellow rust in China

Wild emmer wheat (Triticum dicoccoides) is the progenitor of domesticated wheat and harbors a valuable pool of resistance genes that can be transferred into cultivated wheat. However, little is known about their response to Chinese stripe rust population of Puccininia striiformis f. sp. tritici, which has caused severe yield lost and huge input of pesticides into the environment. In this study, 311 T. dicoccoides genotypes representing 31 populations from the Fertile Crescent were planted in the disease nursery located at Yanting, Sichuan Province of China. We used these genotypes to investigate the virulence composition of the fungal population and the infection types on wild emmer wheat at the seedling and adult stages. The main virulence types of the pathogen at the disease nursery were CY32 and CY33, the most virulent and prevailing race in China. Newly emerged mutant virulent to Yr24 was also detected at a low frequency of 2.17%. Among the 311 genotypes tested, 17 genotypes out of 7 populations demonstrated whole stage resistance to yellow rust. Fifty-six genotypes out from 19 populations were susceptible at the seedling stage but with shown resistance at the adult stage. Water and temperature variables at the places of origin of populations were found to be correlated with the infection types at the disease nurseries. Therefore, wild emmer wheat is a valuable resistance source for China wheat breeding programs against the yellow rust disease.