Development and validation of a Viviparous-1 STS marker for pre-harvest sprouting tolerance in Chinese wheats.

Pre-harvest sprouting (PHS) of wheat reduces the quality of wheat grain, and improving PHS tolerance is a priority in certain wheat growing regions where conditions favorable for PHS exist. Two new Viviparous-1 allelic variants related to PHS tolerance were investigated on B genome of bread wheat, and designated as Vp-1Bb and Vp-1Bc, respectively. Sequence analysis showed that Vp-1Bb and Vp-1Bc had an insertion of 193-bp and a deletion of 83-bp fragment, respectively, located in the third intron region of the Vp-1B gene. The insertion and deletion affected the expression level of the Vp1 at mature seed stage, more correctly spliced transcripts were observed from the genotypes with either insertion or deletion than that of the wild type. Based on these insertions and deletions, a co-dominant STS marker of Vp-1B gene was developed and designated as Vp1B3, which in most cases could amplify either 845 or 569-bp fragment from the tolerant cultivars, and 652-bp from the susceptible ones. This Vp1B3 marker was mapped to chromosome 3BL using a set of Chinese Spring nulli-tetrasomic and ditelosomic lines. A total of 89 white-grained Chinese wheat cultivars and advanced lines, were used to validate the relationship between the polymorphic fragments of Vp1B3 and PHS tolerance. Statistical analysis indicated that Vp1B3 was strongly associated with PHS tolerance in this set of Chinese germplasm, suggesting that Vp1B3 could be used as an efficient and reliable co-dominant marker in the evaluation of wheat germplasm for PHS tolerance and marker-assisted breeding for PHS tolerant cultivars.