Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Plant Cell. 2021 Jul 19;33(6):2058-2071. doi: 10.1093/plcell/koab083.
Drought poses a major environmental threat to maize (Zea mays) production worldwide. Since maize is a monoecious plant, maize grain yield is dependent on the synchronous development of male and female inflorescences. When a drought episode occurs during flowering, however, an asynchronism occurs in the anthesis and silking interval (ASI) that results in significant yield losses. The underlying mechanism responsible for this asynchronism is still unclear. Here, we obtained a comprehensive development-drought transcriptome atlas of maize ears. Genes that function in cell expansion and growth were highly repressed by drought in 50 mm ears. Notably, an association study using a natural-variation population of maize revealed a significant relationship between the level of α-expansin4 (ZmEXPA4) expression and drought-induced increases in ASI. Furthermore, genetic manipulation of ZmEXPA4 expression using a drought-inducible promoter in developing maize ears reduced the ASI under drought conditions. These findings provide important insights into the molecular mechanism underlying the increase in ASI in maize ears subjected to drought and provide a promising strategy that can be used for trait improvement.
干旱对全球范围内的玉米（Zea mays）生产构成了重大环境威胁。由于玉米是雌雄同体植物，玉米籽粒产量取决于雄性和雌性花序的同步发育。然而，当花期发生干旱时，开花和吐丝间隔（ASI）会出现不同步，导致产量显著下降。导致这种不同步的潜在机制尚不清楚。在这里，我们获得了玉米穗全面的发育-干旱转录组图谱。在 50mm 穗中，干旱强烈抑制了细胞扩展和生长相关的基因表达。值得注意的是，利用玉米自然变异群体进行的关联研究表明，α-扩张蛋白 4（ZmEXPA4）表达水平与干旱诱导的 ASI 增加之间存在显著关系。此外，利用干旱诱导启动子在发育中的玉米穗中对 ZmEXPA4 表达进行遗传操作，减少了干旱条件下的 ASI。这些发现为干旱胁迫下玉米穗 ASI 增加的分子机制提供了重要的见解，并为性状改良提供了一种有前途的策略。
