玉米穗长和行粒数的形成与花序分生组织的活性密切相关。植物激素参与花序分生组织活性及其命运调控。项目组前期鉴定并克隆了一个玉米穗长和行粒数相关的QTL EAR LENGTH7(qEL7)，其候选基因（暂命名为EL7）编码一个植物激素合成途径的酶，在花序腋生分生组织特异部位表达。在此基础上，本项目拟：i）通过增强EL7表达和敲除EL7，解析EL7的生物学功能；ii）采用酶动力学分析，体外证实EL7的酶学功能；iii）测定近等基因系、敲除突变体el7和野生型家系的激素水平，结合体外激素处理，鉴定不同基因型的激素水平及其对激素的响应；iv）通过RNA-seq分析、下游基因突变体和双突变体的遗传效应分析等，解析EL7的作用途径；v）应用标记辅助选择改良玉米自交系。该研究结果将丰富我们对玉米花序建成和发育调控的理论认识，也为玉米穗长和行粒数的遗传改良提供新基因资源。

Both ear length and kernel number per row are highly correlated with the maintenance of meristematic activity of meristems in maize inflorescence. Phytohormone biosynthesis and signaling-related genes play a central role in the regulation of the fate and meristematic activity of meristems. Early researches in our laboratory identified and isolated a QTL EAR LENGTH7 (qEL7) for ear length and kernel number per row by map-based cloning. The candidate gene of qEL7, referred to as EL7 which encodes an enzyme involving in biosynthesis of a known phytohormone, expresses in the specific domains of axillary meristems of female inflorescence. In the project, our objectives are: i) to uncover biological function of EL7 by creating transgenic maize lines with enhanced EL7 expression and with EL7 targeted CRISPR knockout; ii) to assay biochemical function of enzyme EL7 in vitro; iii) to measure hormone level in developing inflorescences of parental lines, CRISPR lines and wild type, and to identify the response of different genotypes to exogenous phytohormone; iv) to predict putative regulatory pathway of EL7 using RNA-seq data, and then knockout the key downstream genes to create single mutants and double mutants for genetic assay, take these results together, we hope to reveal the acting pathway of EL7; and v) to improve maize elite lines using marker-aided selection. The outcomes from the project will expand our understanding on the genetic control of inflorescence architecture and development, and provide the available gene for genetic improvement of ear length and kernel number per row in maize.