Li Haoge, Xue Dawei, Gao Zhenyu, Yan Meixian, Xu Wenying, Xing Zhuo, Huang Danian, Qian Qian, Xue Yongbiao
The State Key Laboratory of Rice Biology, College of Life Sciences, Zhejiang University, Hangzhou, 310029 China.
Plant J. 2009 Feb;57(4):593-605. doi: 10.1111/j.1365-313X.2008.03710.x. Epub 2008 Oct 10.
Recent studies have shown that molecular control of inner floral organ identity appears to be largely conserved between monocots and dicots, but little is known regarding the molecular mechanism underlying development of the monocot outer floral organ, a unique floral structure in grasses. In this study, we report the cloning of the rice EXTRA GLUME1 (EG1) gene, a putative lipase gene that specifies empty-glume fate and floral meristem determinacy. In addition to affecting the identity and number of empty glumes, mutations in EG1 caused ectopic floral organs to be formed at each organ whorl or in extra ectopic whorls. Iterative glume-like structures or new floral organ primordia were formed in the presumptive region of the carpel, resulting in an indeterminate floral meristem. EG1 is expressed strongly in inflorescence primordia and weakly in developing floral primordia. We also found that the floral meristem and organ identity gene OsLHS1 showed altered expression with respect to both pattern and levels in the eg1 mutant, and is probably responsible for the pleiotropic floral defects in eg1. As a putative class III lipase that functionally differs from any known plant lipase, EG1 reveals a novel pathway that regulates rice empty-glume fate and spikelet development.
最近的研究表明，单子叶植物和双子叶植物在内部花器官身份的分子控制方面似乎大体上是保守的，但对于单子叶植物外部花器官（禾本科植物中一种独特的花结构）发育的分子机制却知之甚少。在本研究中，我们报道了水稻额外颖片1（EG1）基因的克隆，该基因是一个推定的脂肪酶基因，它决定了空颖片的命运和花分生组织的确定性。除了影响空颖片的身份和数量外，EG1的突变还导致在每个器官轮或额外的异位轮中形成异位花器官。在雌蕊的推定区域形成了重复的颖片状结构或新的花器官原基，导致花分生组织不确定。EG1在花序原基中强烈表达，在发育中的花原基中弱表达。我们还发现，花分生组织和器官身份基因OsLHS1在eg1突变体中的表达模式和水平都发生了改变，并且可能是导致eg1多效性花缺陷的原因。作为一种推定的III类脂肪酶，其功能不同于任何已知的植物脂肪酶，EG1揭示了一条调节水稻空颖片命运和小穗发育的新途径。
