Drought is one of the major abiotic stresses affecting the maize production worldwide. As a cross-pollination crop, maize is sensitive to water stress at flowering stage. Drought at this stage leads to asynchronous development of male and female flower organ and increased interval between anthesis and silking, which finally causes failure of pollination and grain yield loss. In the present study, the expansin gene ZmEXPA5 was cloned and its function in drought tolerance was characterized. An indel variant in promoter of ZmEXPA5 is significantly associated with natural variation in drought-induced anthesis-silking interval. The drought susceptible haplotypes showed lower expression level of ZmEXPA5 than tolerant haplotypes and lost the cis-regulatory activity of ZmDOF29. Increasing ZmEXPA5 expression in transgenic maize decreases anthesis-silking interval and improves grain yield under both drought and well-watered environments. In addition, the expression pattern of ZmEXPA5 was analyzed. These findings provide insights into the genetic basis of drought tolerance and a promising gene for drought improvement in maize breeding.

干旱是影响全球玉米生产的主要非生物胁迫之一。玉米作为异花授粉作物，在开花期对水分胁迫敏感。此阶段的干旱导致雄花和雌花器官发育不同步，花期和吐丝间隔时间延长，最终导致授粉失败和粮食减产。在本研究中，克隆了扩展蛋白基因ZmEXPA5，并表征了其在耐旱性中的功能。ZmEXPA5启动子中的插入缺失变异与干旱诱导的开花-吐丝间隔的自然变化显着相关。干旱易感单倍型表现出比耐旱单倍型更低的ZmEXPA5表达水平，并且失去了ZmDOF29的顺式调节活性。在转基因玉米中增加ZmEXPA5表达可缩短花期间隔并提高干旱和水分充足环境下的谷物产量。此外，还分析了ZmEXPA5的表达模式。这些发现为了解耐旱性的遗传基础和玉米育种中干旱改良的有希望的基因提供了见解。