Characterization of Tamyb10 allelic variants and development of STS marker for pre-harvest sprouting resistance in Chinese bread wheat

Wheat grain color does not only affect the brightness of flour but also seed dormancy and pre-harvest sprouting (PHS) tolerance. The transcription factor Tamyb10 is an important candidate for R-1 gene, and the expression of its homologs determines wheat seed coat color. In the present study, the allelic variations of Tamyb10 were explored in a set of Chinese bread wheat varieties and advanced lines with different PHS tolerance, and a sequenced-tagged site (STS) marker for Tamyb10-D1 gene was developed, designated as Tamyb10D, which could be used as an efficient and reliable marker to evaluate the depth dormancy of wheat seeds. Using the marker Tamyb10D, 1629- and 1178-bp PCR fragments were amplified from the tolerant varieties, whereas a 1178-bp fragment was from the susceptible ones. Of the Chinese bread wheat varieties and advanced lines, 103 were used to validate the relationship between the polymorphic fragments of Tamyb10D and PHS tolerance. Statistical analysis indicated that Tamyb10D was significantly (P < 0.001) associated with depth of seed dormancy in these germplasms. To further confirm the association between allelic variants of Tamyb10-D1 and PHS tolerance, 200 recombinant inbred lines (RILs) from the cross between Zhongyou 9507 (1178-bp fragment) and Yangxiaomai (1178- and 1629-bp fragments) were genotyped using the marker Tamyb10D. General linear model analysis indicated that variation in Tamyb10-D1 had a significant (P < 0.001) association with the germination index (GI) values, explaining 13.7, 4.7, and 9.8 % of the phenotypic variation in GI in Shijiazhuang, Beijing, and the averaged data from those environments, respectively. In addition, among the 103 wheat varieties, 8 Tamyb10 genotypes (Tamybl0-A1, Tamybl0-B1, and Tamyb10-D1 loci) were detected, namely, aaa, aab, aba, abb, baa, bab, bba, and bbb, and these were significantly associated with GI value.