粮食安全是人类面临的最重要的挑战之一。玉米作为主要的食物来源对保障粮食安全有至关重要的意义。MicroRNA (miRNA) 是一类单链非编码小RNA对作物诸多重要的农艺性状发挥关键的调控作用，因而成为新的作物遗传改良目标。miRNA作为复杂基因调控网络的中心控制作物的生长和胁迫响应，然而对它们作用机制还了解甚少。miR398是植物保守的miRNA，在植物中参与多种逆境胁迫响应过程，而在玉米中的功能还未有报道。本项目前期研究结果发现miR398表达量降低造成玉米籽粒变小，而过表达miR398造成玉米籽粒变大，表明玉米miR398具有调控籽粒发育的功能。本项目将进一步研究miR398调控产量相关性状的功能，并通过生物信息学的方法筛选miR398新的靶基因，通过实验研究其分子作用机制，构建基因调控网络，为玉米遗传改良提供理论基础。

Food security is one of the most important challenges facing humanity. As the main food source, Maize (Zea mays) is of vital importance for ensuring food security. MicroRNAs (miRNAs), a type of single-stranded non-coding small RNA, play key roles in regulating many agriculturally important traits in crops, and thus become promising candidates for crop genetic improvement. miRNAs act as master modulators of complex gene expressions to control crop growth and stress responses, while the mechanisms of their actions are largely unknown. miR398 is a plant-conserved miRNA that participates various stress response processes in plants, while its function in maize has not been reported. In previous study, we found that the reduced expression of miR398 lead to smaller kernel size, while miR398 overexpression lead to larger kernel size, indicating miR398 plays a role in kernel development in maize. This project will further study the function of miR398 in regulating yield-related traits in maize and screen new target genes of miR398 through bioinformatic methods，study its molecular mechanisms through experiments，construct a gene regulatory network, and provide a theoretical basis for maize genetic improvement.