Mapping a major QTL for hairy leaf sheath introgressed from Aegilops tauschii and its association with enhanced grain yield in bread wheat

Aegilops tauschii, the diploid D genome progenitor of the hexaploid wheat, has been used to improve modern common wheat by creating synthetic hexaploid wheat (SHW) as a bridging mechanism for wheat breeding. Most Ae. tauschii accessions have hairiness on the leaf sheath, whereas the hexaploid common wheat is usually glabrous. In this study a major QTL for leaf sheath hairiness (LSH) was detected on the long arm of chromosome 4D in two recombinant inbred line (RIL) populations produced from SHW-derived cultivar Chuanmai 42. The QTL peak was flanked by markers Xbarc48 and Xbarc1183/D_GB5Y7FA01AGCKH_224, and explained more than 75 % of the phenotypic variation. The QTL allele for LSH was contributed by Chuanmai 42, and originated from Ae. tauschii. In both RIL populations the QTL allele producing hairy leaf sheath was significantly and positively associated with increased grain yield, grain weight and grain weight per spike. Moreover, most Chuanmai 42-derived cultivars have inherited the hairy leaf sheath character. These findings suggest that the hairy leaf sheath gene in Chuanmai 42 can be applied in marker-assisted selection (MAS) as a morphologically selectable marker in breeding for high yield.