Stamen development in Arabidopsis is arrested by organ-specific overexpression of a cucumber ethylene synthesis gene CsACO2
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Cucumber (Cucumis sativus L.) has served as a model to understand hormone regulation in unisexual flower development since the 1950s and the role of ethylene in promoting female flower development has been well documented. Recent studies cloned the F-locus in gynoecious lines as an additional copy of the ACC synthase (ACS) gene, which further confirmed the role of ethylene in the promotion of female cucumber flowers. However, no direct evidence was generated to demonstrate that increases in endogenous ethylene production could induce female flowers by arresting stamen development. To clarify the relationship between ethylene production and stamen development, we overexpressed the ethylene synthesis cucumber gene CsACO2 to generate transgenic Arabidopsis, driven by the organ-specific promoter P AP3 . We found that organ-specific overexpression of CsACO2 significantly affected stamen but not carpel development, similar to that in the female flowers of cucumber. Our results suggested that increases in ethylene production directly disturb stamen development. Additionally, our study revealed that among all floral organs, stamens respond most sensitively to exogenous ethylene.
KeywordsCsACO2 Cucumber unisexual flower development Female flowers Transgenic Arabidopsis
Cucumis sativus ACC oxidase gene2
Arabidopsis gene Apetala3
Arabidopsis gene Crab’s Claw
The dominant negative Arabidopsis ethylene response mutant gene
We thank Cong Li and Hong-Bo Pang for their contributions to the project when they worked in our lab as student assistants. We are grateful to Yi-Ben Peng and Su-Lan Bai for their technical assistance in morphological analysis. We would like to give special thanks to Prof. Zhong-Ping Lin at the College of Life Sciences, Peking University for his help in constructing transgenic plants, Prof. Xing-Qiang He and Yu Pang for their help in analysis of PCD in transgenic Arabidopsis. This work was supported by grants to S-N.B. from MST (J00-A-005, G19990116, 2007CB1087), NSFC (30070361), and to Z-H.X from MST.
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