CsmiR164介导的乙烯信号调控对黄瓜性型分化的作用机制

According to several sexual types of flowers, cucumber (Cucumis sativus L.) is considered as a model to research the development biology of plant flower. In cucumber, all of the main sexual genes, F, M and A, are members of ACC synthase gene family, which shows that ethylene biosynthesis and signaling are the crucial factors for sex determination. According to microRNA sequencing of different sexual cucumber lines, the expression level of CsmiR164 was lower significantly, and its predicted target CsORE1 was expressed at a significant high level in the floral buds of FFMM genotype. More expression analyses indicated that the CsmiR164 would be important for cucumber sex determination. In this project, we will study the functions of CsmiR164, CsORE1 and CsEIN3, and their regulation network with M gene to explore the effect of CsmiR164-mediated modulation for sex differentiation and development of cucumber flowers, which should improve the positive feedback model of ethylene signaling in cucumber sex-determination. In Arabidopsis, the regulatory network with those genes controls the process of age-associated programmed cell death to mediate leaf senescence, which model would have crucial effect in sex-determination of cucumber, and find miR164 and ORE1 more functions.

黄瓜的花存在多种性型，是研究植物花发育生物学较理想的模式植物。黄瓜3个主要性型基因F、M和A均是ACC合酶家族基因，说明乙烯的合成与信号传导是性型分化的关键因素。在不同性型黄瓜microRNA测序分析中，FFMM基因型花芽的CsmiR164表达显著降低，其预测靶基因CsORE1的表达显著上调。通过进一步表达分析初步证实了CsmiR164很可能在黄瓜的花芽性别决定中发挥重要作用。本研究将通过对CsmiR164、CsORE1和CsEIN3的功能分析，验证其与M基因间的调控关系，探究CsmiR164介导的调控过程在黄瓜花芽性型分化与发育中的作用，完善黄瓜乙烯信号正向自反馈的调控通路模型，有助于黄瓜性型决定的分子机制研究。在拟南芥中，这几个基因形成的调控模式主要控制叶片衰老中依赖年龄的程序性细胞死亡过程，而该模式在黄瓜中很可能与性型分化密切相关，这将对miR164和ORE1的功能研究有重大拓展。

性别决定是高等植物生长发育的重要生物学过程。本研究以黄瓜为材料，通过miRNA测序分析发现，CsmiR164c及其靶基因CsNAC2参与乙烯介导的雌花分化过程。基因功能分析结果显示，CsNAC2的表达响应乙烯信号，异源表达CsNAC2具有调控拟南芥雌蕊分化的功能，推测其具有调控黄瓜雌性器官发育的功能。通过实验证实，“CsERF31-CsACS2”调控模块是黄瓜雌花芽中特异积累乙烯的关键，促进雌花分化的初始乙烯信号通过CsEIN3激活CsERF31表达，进而调控CsACS2积累，形成正反馈循环，使花芽分化为雌花。本研究初步鉴定出乙烯介导的黄瓜雌花分化的调控模型，为深入解析黄瓜性别决定的分子机制提供重要参考。