Zhang Yan, Zhang Xiaolan, Liu Bin, Wang Wenjiao, Liu Xingwang, Chen Chunhua, Liu Xiaofeng, Yang Sen, Ren Huazhong
College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, P. R. China Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, China Agricultural University, Beijing 100193, P. R. China.
College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, P. R. China Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, China Agricultural University, Beijing 100193, P. R. China
J Exp Bot. 2014 Jul;65(12):3201-13. doi: 10.1093/jxb/eru176. Epub 2014 Apr 30.
Cucumber (Cucumis sativus L.) is a typical monoecious vegetable with individual male and female flowers, and has been used as a model plant for sex determination. It is well known that sex differentiation of cucumber can be regulated by phytohormones, such as gibberellic acid (GA) and ethylene. The molecular mechanism of female sex expression modulated by ethylene has been widely understood, but how GA controls male sex expression remains elusive. In hermaphroditic Arabidopsis and rice, GA can regulate stamen and anther development via the transcriptional regulation of GAMYB. Here we characterized a GAMYB homologue CsGAMYB1 in cucumber. We found that CsGAMYB1 is predominantly expressed in male flower buds, where its expression is upregulated by GA3 treatment. CsGAMYB1 protein is localized in the nucleus. CsGAMYB1 can partially rescue stamen development and fertility phenotypes of an Arabidopsis myb33 myb65 double mutant. However, constitutive overexpression of CsGAMYB1 in wild-type Arabidopsis resulted in male sterility, which mimics the effect of GA overdose in flower development. Knockdown of CsGAMYB1 in cucumber decreases the ratio of nodes with male and female flowers, and ethylene is not involved in this process. Our data suggest that CsGAMYB1 regulates sex expression of cucumber via an ethylene-independent pathway.
黄瓜（Cucumis sativus L.）是一种典型的雌雄同株蔬菜，具有单性的雄花和雌花，并且已被用作性别决定的模式植物。众所周知，黄瓜的性别分化可受植物激素调控，如赤霉素（GA）和乙烯。乙烯调控雌性性别表达的分子机制已被广泛了解，但GA如何控制雄性性别表达仍不清楚。在雌雄同体的拟南芥和水稻中，GA可通过GAMYB的转录调控来调节雄蕊和花药发育。在此，我们鉴定了黄瓜中的一个GAMYB同源基因CsGAMYB1。我们发现CsGAMYB1主要在雄花芽中表达，其表达在GA3处理后上调。CsGAMYB1蛋白定位于细胞核。CsGAMYB1可以部分挽救拟南芥myb33 myb65双突变体的雄蕊发育和育性表型。然而，在野生型拟南芥中组成型过表达CsGAMYB1导致雄性不育，这模拟了GA过量对花发育的影响。在黄瓜中敲低CsGAMYB1会降低雄花和雌花节位的比例，且乙烯不参与此过程。我们的数据表明，CsGAMYB1通过一条不依赖乙烯的途径调控黄瓜的性别表达。
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