玉米穗长主效QTLQ21EL-GZ的精细定位与候选基因克隆

穗长作为产量的重要构成因子之一，通过影响单穗籽粒数进而影响产量。前期研究显示，玉米穗长主效QTLQ21EL-GZ在关联和连锁分析中均被检测到，其中在“黄早四×Mo17”的RIL家系中具有较高的遗传效应，可解释17.38%的穗长变异；本项目拟以QTL Q21EL-GZ为靶标，以黄早四为轮回亲本构建目标区段的次级分离群体；整合QTL分离技术极端表型样本混池以及基于高通量测序的新方法 QTG-Seq 用于Q21EL-GZ的快速精细定位与克隆。并在此基础上，通过比对、分析目标区域内的基因序列，结合MaizeGDB预测的基因时空表达模式，确定Q21EL-GZ的候选基因。通过构建过表达载体和CRISPR/Cas9敲除载体，考察过表达株系、敲除株系及野生型的穗长变化，最终验证Q21EL-GZ调控玉米穗长形成的生物学功能。研究结果可以明确穗长候选基因的分子机制，为高产玉米育种和新种质创制等提供科学支撑。

Ear length (EL) is one of the most important factors, which could impact the formation of maize grain yield, indirectly.Our previous research showed that one QTL of Q21EL-GZ was found, supported by GWAS and linkage at the same time by integrating multiple populations together. It can explain 17.38% of EL variation. In here, based on the segregating population constructed from the recurrent parent HZS, we perform a new method QTG-seq which combined with QTL separation techniques of sequencing of bulked segregant pools from an extremely phenotypic population to fine and identify the Q21EL-GZ. And then, align the target gene region and predict the target gene expression pattern in MazieGDB website. To estimate the candidate gene function, we construct with the transgenic lines to test the candidate gene functional validation, such as overexpression lines or CRISPR/Cas9 knockout lines. We observe the ear length of transgenic lines and wild type, finally, the biological function of Q21EL-GZ in regulating ear length formation was verified. The research can explain the candidate gene regulation function, which could provide scientific support for higher yield and contribute for maize breeding new germplasm.