黄瓜是世界十大蔬菜作物之一，果实为其经济库器官。(维管束)韧皮部结构、极性和卸载功能影响果实同化物积累与形态建成，在果实发育中起着关键作用。申请者前期利用黄瓜果实韧皮部转录组学筛选和反向遗传学方法，初步观察到黄瓜韧皮部特异表达基因CsDFB1过表达株系通过影响韧皮部结构、分布和极性，从而造成果实发育异常。本项目拟以黄瓜韧皮部特异表达基因CsDFB1为切入点，系统分析其调控果实发育的上游信号途径及下游基因网络。拟运用原位杂交等方法，分析其组织表达特性；利用过表达和基于CRISPR/Cas9技术的基因敲除，确认CsDFB1生物学功能；通过酵母单杂交等筛选其上游调节因子；结合转录组学和免疫共沉淀联合质谱技术等构建其下游互作网络。本项目有望明确CsDFB1基因调控韧皮部结构、极性和卸载功能影响黄瓜果实发育的分子生理机制，为黄瓜品质改良育种提供新的基因资源，为黄瓜高产优质栽培及其调控提供理论依据。

Cucumber（Cucumis sativus L.） is one of the most important vegetable crops worldwide. As the sink organ, fruit determines its economic value. The phloem structure, polarity, and unloading can influence fruit assimilates accumulation and morphological development, which playing a key role during fruit development. Combined RNA-Seq and reverse genetics methods, we found that overexpression of a phloem-specific gene caused deformed fruit by affecting phloem structure, distribution and polarity. Therefore, this gene was named as CsDFB1 (Deformed Floral Bud 1). Here, we attempt to analyze how CsDFB1 plays its role in fruit development. We will identify the expression profile of CsDFB1 by in situ hybridization. The transgenic lines overexpressing and CRISPR/Cas9-mediated targeted mutagenesis of CsDFB1 gene will be generated to confirm its function, respectively. On one hand, we will isolate the promoter of CsDFB1 and screen the possible regulator upstream to CsDFB1 gene by using yeast one hybrid screening. On the other hand, we will identify the downstream genes of CsDFB1 protein by RNA-Seq and CoIP-MS approaches using transgenic lines. Our findings could expect to establish the possible molecular and physiological mechanism of CsDFB1 in regulating fruit development by affecting the phloem structure, polarity and unloading. Moreover, it also contributes to provide new gene resources and theoretical basis for cucumber quality improvement breeding and cultivation.