黄瓜心皮数对提高黄瓜果实单果重和改良商品性状具有重要意义。申请人前期研究表明，该性状是由CsCLAVATA3基因调控的简单质量性状，不同心皮黄瓜材料中该基因外显子序列相同，在翻译起始位点5’上游-1074bp的单碱基突变与心皮数性状关联，且CsCLAVATA3基因与拟南芥CLAVATA3基因结构差异较大。为了进一步解析该突变位点调控黄瓜心皮数的机理，本研究拟克隆CsCLAVATA3启动子序列，构建启动子GUS融合载体，设计一系列5’端缺失删减实验，在黄瓜中进行遗传转化，并通过 GUS 染色和RT-qPCR表达量检测获得启动子核心序列，分析核心序列的结构与特征。之后，通过凝胶迁移实验验证突变位点结合的转录因子，阐明CsCLAVATA3基因启动子的生物学功能，揭示突变位点对CsCLAVATA3启动子活性和基因表达的影响，为单碱基突变导致心皮数发生变化提供理论依据。

The carpel number of cucumber fruit is of significant important for increasing fruit weight and improving commodity traits. Our previous studies have shown that carpel number variation in cucumber is controlled by a single gene, Cn, and linkage and association analysis revealed CsCLAVATA3 as the candidate gene of the Cn locus. A single-nucleotide mutation of upstream 1074 bp from the translation initiation site, was associated with Cn. The structure of CsCLAVATA3 gene is very different from the CLAVATA3 gene in Arabidopsis thaliana. In order to explain the connection between the single-nucleotide mutation and CsCLAVATA3, the promoter of CsCLAVATA3 was cloned, and a series of constructs with 5' deletions of the CsCLAVATA3 promoter vector will be employed. By genetic transformation of cucumber and GUS expression of cucumber organs, the core region of CsCLAVATA3 promoter will be scanned. We will predict and analyze the structure and features of the core region and verify the transcription factor binding with single-nucleotide mutation by EMSA-electrophoretic mobility shift assay. Summary, we will analyze the biological function of the CsCLAVATA3 promoter and elucidate the mechanism of the single-nucleotide mutation regulating the activity of CsCLAVATA3 gene. We will also provide the theoretical basis for the variation of Cn caused by the single-nucleotide mutation, and we will solidify a foundation for the cucumber carpel number regulating mechanism and molecular assisted selection breeding.