National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology & Ecology, Shanghai, 200032, China.
University of the Chinese Academy of Sciences, Beijing, 100049, China.
Nat Commun. 2020 Oct 22;11(1):5346. doi: 10.1038/s41467-020-19196-9.
The mechanism that creates vitreous endosperm in the mature maize kernel is poorly understood. We identified Vitreous endosperm 1 (Ven1) as a major QTL influencing this process. Ven1 encodes β-carotene hydroxylase 3, an enzyme that modulates carotenoid composition in the amyloplast envelope. The A619 inbred contains a nonfunctional Ven1 allele, leading to a decrease in polar and an increase in non-polar carotenoids in the amyloplast. Coincidently, the stability of amyloplast membranes is increased during kernel desiccation. The lipid composition in endosperm cells in A619 is altered, giving rise to a persistent amyloplast envelope. These changes impede the gathering of protein bodies and prevent them from interacting with starch grains, creating air spaces that cause an opaque kernel phenotype. Genetic modifiers were identified that alter the effect of Ven1, while maintaining a high β-carotene level. These studies provide insight for breeding vitreous kernel varieties and high vitamin A content in maize.
成熟玉米籽粒中玻璃质胚乳的形成机制尚不清楚。我们鉴定了 Vitreous endosperm 1（Ven1）是影响这一过程的主要数量性状位点。Ven1 编码β-胡萝卜素羟化酶 3，该酶调节质体膜中类胡萝卜素的组成。A619 自交系含有一个无功能的 Ven1 等位基因，导致质体中非极性类胡萝卜素增加，极性类胡萝卜素减少。巧合的是，在玉米籽粒干燥过程中，质体膜的稳定性增加。A619 胚乳细胞的脂质组成发生改变，导致质体膜持久存在。这些变化阻碍了蛋白体的聚集，阻止它们与淀粉粒相互作用，形成空气空间，导致不透明的籽粒表型。鉴定到了改变 Ven1 效应的遗传修饰因子，同时保持高β-胡萝卜素水平。这些研究为培育玻璃质玉米品种和提高玉米中维生素 A 含量提供了深入的了解。
