Conservation of the E-function for floral organ identity in rice revealed by the analysis of tissue culture-induced loss-of-function mutants of the OsMADS1 gene
Conservation of the E-function for floral organ identity in rice revealed by the analysis of tissue culture-induced loss-of-function mutants of the OsMADS1 gene
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DOI：
10.1007/s11103-005-2161-y
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发表时间：
2005-09-01
影响因子：
5.1
通讯作者：
Hirochika, H
中科院分区：
文献类型：
--
作者：
Agrawal, G;Abe, K;Hirochika, H
随着花发育研究的不断深入，人们将经典的ABC模型改进为新的ABCDE模型，从而更好地解释了花器官身份的调控。双子叶植物花器官同一性的E-功能的保守性已被揭示。然而，它在单子叶植物中的保护仍然是未知的。在这里，我们展示了水稻（Oryza sativa L.）通过表征两个MADS盒基因OsMADS 1和OsMADS 5的组织培养诱导的突变体，所述突变体在SEP基因（E功能）进化系的得到充分支持的进化系内形成亚进化系。OsMADS 1的严重功能丧失突变导致三个内轮的器官（浆片、雄蕊和心皮）完全同源异型转化为外稃和内稃样结构。这种基本的变形结构在同一小花的中心沿着花梗重复，表明花分生组织的确定性丧失。这些表型与双子叶植物的E类基因如拟南芥SEP 1/2/3（SEPALLATA 1/2/3）和矮牵牛属FBP 2（花结合蛋白2）突变所引起的表型相似，表明OsMADS 1在水稻中发挥的作用与双子叶植物中所定义的E类基因非常相似。在OsMADS 5的功能丧失突变的情况下，未观察到穗或营养器官的缺陷。这些结果表明OsMADS 1明显具有E功能，因此，E功能在双子叶植物和单子叶模式植物水稻之间基本上是保守的。
Rapid progress in studies on flower development has resulted in refining the classical 'ABC model' into a new 'ABCDE model' to explain properly the regulation of floral organ identity. Conservation of E-function for flower organ identity among the dicotyledonous (dicot) plants has been revealed. However, its conservation in monocotyledonous (monocot) plants remains largely unknown. Here, we show the conservation of E-function in rice (Oryza sativa L.) by characterizing tissue culture-induced mutants of two MADS-box genes, OsMADS1 and OsMADS5, which form a subclade within the well- supported clade of SEP-genes (E-function) phylogeny. Severe loss-of-function mutations of OsMADS1 cause complete homeotic conversion of organs (lodicules, stamens, and carpels) of three inner whorls into lemma- and palea-like structures. Such basic deformed structure is reiterated along with the pedicel at the center of the same floret, indicating the loss of determinacy of the flower meristem. These phenotypes resemble the phenotypes caused by mutations of the dicot E-class genes, such as the Arabidopsis SEP123(SEPALLATA1/2/3) and the petunia FBP2(Floral Binding Protein 2), suggesting that OsMADS1 play a very similar role in rice to that of defined E-class genes in dicot plants. In case of the loss-of-function mutation of OsMADS5, no defect in either panicles or vegetative organs was observed. These results demonstrate that OsMADS1 clearly possesses E-function, and so, E-function is fundamentally conserved between dicot plants and rice, a monocot model plant.