Identification of a High-Yield Introgression Locus in Chuanmai 42 Inherited from Synthetic Hexaploid Wheat

Synthetic hexaploid wheat (SHW), a carrier of multiple elite genes, is an important genetic resource in improvement of common wheat (Triticum aestivum L.). Chuanmai 42 is a wheat cultivar with high-yield potential and resistance to strip rust (Puccinia striiformis f. sp. tritici), which was developed by crossing and backcrossing Syn769 (an elite synthetic hexaploid wheat) with Sichuan commercial wheat cultivars. For understanding the genetic effects of the introgression loci from SHW in Chuanmai 42, a total of 78 introgression loci of SHW were tested in Chuanmai 42 using 1029 simple sequence repeat (SSR) markers. Using 127 recombinant inbred lines (RILs, F₈) in Chuanmai 42 (introgression loci) and Chuannong 16 (Chuannong 16 loci) backgrounds, the genetic effects of the introgression loci were evaluated across 6 environments in Sichuan Province, China from 2006 to 2009. One locus from the SHW parent, Barc1183, was detected in Chuanmai 42. It was located on the long arm of chromosome 4D after idenfication using the 4DS and 4DL telosomic lines of Chinese Spring and the 4D(4A) and 4D(4B) substitution lines of Longdon (T. turgidum subsp. durum). This locus had positive effects on increasing tiller number per plant, number of effective spikes, grains per square meter, harvest index, and grain production rate. The average yield of the 6 growing environments was increased by 8.9% when comparing locus Barc1183 in Chuanmai 42 to that in Chuannong 16. Therefore, Barc1183 from SHW is a candidate locus in high-yield breeding of wheat.