Identifying alleles of Viviparous-1B associated with pre-harvest sprouting in micro-core collections of Chinese wheat germplasm

Abstract

Wheat pre-harvest sprouting (PHS) is an undesired trait, which often reduces yield and downgrades end-use quality of grain. Viviparous-1B (Vp-1B), a regulator gene located on chromosome 3B, has previously been proved to be involved in inducing grain dormancy of wheat. In order to obtain some new or useful alleles associated with PHS tolerance of white-grained wheat, we developed a gene-specific marker (Vp1-b2) to identify allelic variations of Vp-1B using denaturing PAGE in micro-core collections of Chinese wheat and landraces. As a main component observed genetic variation for PHS, seed dormancy evaluated by germination index (GI) was determined at dough-yellow ripening stage in the present study. The results indicated that six alleles of Vp-1B, in our study, were discovered among 276 Chinese wheat varieties. Of these alleles, two variants were validated to be novel alleles and designated as Vp-1Be and Vp-1Bf, respectively. By investigating the association between allelic variations of Vp-1B and seed dormancy, we found allele of Vp-1Ba always inclined to weak seed dormancy and susceptibility to PHS. Up to 62.2% genotypes carrying the allele had high GI value with a range of 0.51–1.00, only 14.4% genotypes had low GI value under 0.30. On the contrary, other variants such as Vp-1Bb, Vp-1Bc, Vp-1Bd, Vp-1Be and Vp-1Bf mostly occurred in varieties with higher PHS tolerance, which average of GI values were 0.204, 0.227, 0.296, 0.256 and 0.186, respectively. In Chinese wheat germplasms, Vp-1Ba and Vp-1Bc showed the most widespread distribution followed by Vp-1Bb; other alleles fell into less used varieties. Our research confirmed rich allelic variation of Vp-1B occurred in micro-core collections of Chinese wheat and landraces, which may be useful for improving PHS tolerance as breeding parents.