Distribution of genes associated with yield potential and water-saving in Chinese Zone II wheat detected by developed functional markers

Functional markers (FMs) developed from sequence polymorphisms are present in allelic variants of a functional gene at a locus and are directly associated with phenotypic variations. In this study, FM linked to Rht-B1, Rht-D1, TaCwi-A1, TaSus2-2B, TaGW2-6A and Dreb-B1 genes conferring to yield potential and water-saving were selected to analyse the distribution in 102 wheat varieties, most of which were authorized in the past decade and adapted to grow in Zone II of China. First, the semidwarfing genes Rht-B1b and Rht-D1b (mutant alleles) conferring to grain yield were analysed. The frequencies of favourable alleles Rht-B1b and Rht-D1b were 32.4 and 58.8%, respectively. Comparing with the previous report, the frequency of Rht-B1b among cultivars in this study is similar to the frequency among cultivars released in the 1990s, while the frequency of Rht-D1b is slightly lower than the previous report 63.9%. Twelve (11.8%) cultivars neither contained Rht-B1b nor Rht-D1b, while only Yumai 66 contained both semidwarfing genes. Linyuan8 and Xinong 928 are heterozygous at RhtB1 locus and Zhengmai 9023 is heterozygous at both RhtB1 and Rht-D1 loci. Second, the TaCwi-A1, TaSus2-2B and TaGW2-6A genes considered as candidate genes related to grain weight were detected. We found that the frequencies of the favourable alleles were 76.5, 56.9 and 69.6%, respectively. Among the 102 wheat varieties, 30 contained all the three favourable genes, 45 contained two of the three favourable genes and 27 contained only one. There are eight wheat varieties (7.8%) in hybrid state at the TaCWI-A1 locus. Third, the designed FM linked to water-saving gene Dreb-B1 were validated on 102 wheat varieties. The results showed that the haplotypes of 47 wheat varieties at the Dreb-B1 locus were same as that of Opata 85, and 55 wheat varieties showed the signal expected for W7984 (Opata 85 and W7984 are parents of the ITMI mapping population). This information will be useful for the wheat breeding programmes aiming at improving yield and water use efficiency in Shijiazhuang located in China Zone II.