Molecular mapping and candidate gene analysis of the semi-dominant gene Vestigial glume1 in maize

The glume is an organ of the maize spikelet and plays important roles in anther and kernel development. Vestigial glume1 (Vg1) is a classic mutant associated with ligule and glume development. Here we report the phenotypic characterization, fine mapping, and candidate gene analysis of the Vg1 mutant. Vg1 is a semi-dominant and pleiotropic gene, and also affects plant height, ear height, and tassel length. Vg1 ligule degeneration begins at the first leaf, and the Vg1 tassel and ear can be distinguished from those of wild-type plants when their lengths reach respectively 55 mm and 51 mm. Using a BC3 mapping population of 11,445 plants, we delimited the Vg1 functional site to an interval of 7.4 kb, flanked by the markers InDelLM and CRM6. A putative cyclopropane fatty-acid synthase gene (ZmCPA-FAS1) was hypothesized to underlie the mutant phenotype. We detected a Helitron insertion in the sixth intron of ZmCPA-FAS1. Its presence caused abnormal alternative splicing of ZmCPA-FAS1 that conferred new characteristics on the Vg1 mutant. These findings are a basis for further discovery of the molecular mechanism underlying glume development and a potential guide for maize breeding of small-glume varieties, especially sweet corn breeding.