What can the Viviparous-1 gene tell us about wheat pre-harvest sprouting?

Pre-harvest sprouting (PHS) of wheat greatly reduces the quality and economic value of grain, and PHS tolerance is one of the most important traits in wheat breeding. Two new Vp-1B alleles were identified in wheat genotypes with distinct PHS tolerance and ABA responsiveness and designated as Vp-1Bb and Vp-1Bc. These alleles had an insertion of 193-bp and a deletion of 83-bp in the third intron in the region of B3 domain, respectively. Further analysis indicated that different Vp-1B alleles showed different expression and responsiveness to ABA exposure at transcriptional level, implying that they may regulate PHS tolerance. Based on these alleles, a STS marker Vp1B3 was developed and validated among a set of 89 Chinese wheat accessions. The results indicated that Vp1B3 may be useful 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. Moreover, analysis of a collection of 490 EU winter wheat varieties revealed not only the prevalence of Vp-1B alleles but also a new allele Vp-1Bd which does not occur in Chinese wheats.