Analysis of molecular mechanisms involved in the evolution of plant morphology

植物形态演化的分子机制分析

基本信息

批准号：
09640736
负责人：
KYOZUKA Junko
金额：
$ 1.54万
依托单位：
NARA INSTITUTE OF SCIENCE AND TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 2000
项目状态：
已结题

项目摘要

The floral morphology of grass species is distinct from typical dicot plants. In order to achieve a better understanding of the molccular basis for this diversion, we isolated RAP1A, RAP1B and RAG, putative rice homologs for the Arabidopsis class A gene APETALA1(AP1) and class C gene AGAMOUS(AG), respectively. Expression patterns of RAP1A.RAG, and OsMADS2, a rice homolog of the class B gene, were analyzed by in situ hybridization. RAP1A mRNA was expressed in the apical region of the floral meristem at an early stage of spikelet development, and then its expression was localized in developing lemma, palea and lodicules. OsMADS2 transcript was first observed in the region where stamen primordia are formed. Soon after, OsMADS2 mRNA appeared in the lodicule primordia as well as stamen primordia and this RNA accumulation pattern persisted till late stages of floral development. The expression of RAG was observed in stamens and pistils of wild type young spikelets. These RNA accumulation pat … More terns are mostly similar to those of Arabidopsis class A, B, C genes supporting the notion that the ABC model may be extended to rice.In order to clarify the evolutionary relationship between grass sterile organs, such as lodicules, the lemma and the palea, and the dicot floral organs, we expressed RAG, a rice (Oryza sativa L.) AGAMOUS(AG) ortholog, in rice plants under the control of an Actin I promoter.As a consequence of the ectopic expression of the RAG, lodicules were homeotically transformed into stamens. In total, the transformation of lodicules to staminoid organs was observed in 18 out of 26 independent transgenic lines. In contrast to the almost complete transformation occurred in lodicules, none of the transgenic plants exhibited any morphological alterations in the palea or the lemma. Our results confirmed the prediction that the lodicule is an equivalent of a dicot petal and that the ABC model can be applied to rice at least for organ specification in lodicules and stamens. On the other hand, the absence of morphological alterations in the palea or the lemma raised the possibility that the simple application of the ABC model to structures outside the lodicules may not be valid. Less

禾本科植物的花形态与典型的双子叶植物不同，为了更好地了解这种转移的分子基础，我们分离了 RAP1A、RAP1B 和 RAG，它们是拟南芥 A 类基因 APETALA1(AP1) 的假定水稻同源物。分别分析了C类基因AGAMOUS(AG)和B类基因的水稻同源物OsMADS2的表达模式。原位杂交显示，RAP1A mRNA 在小穗发育早期在花分生组织的顶端区域表达，随后其表达定位于发育中的外稃、内稃和浆片，OsMADS2 转录物首先在雄蕊原基所在区域观察到。形成后不久，OsMADS2 mRNA 出现在浆片原基和雄蕊原基中，并且这种 RNA 积累模式持续到花发育后期。在野生型幼小穗的雄蕊和雌蕊中观察到 RAG 的表达，这些燕鸥的 RNA 积累模式与拟南芥 A、B、C 类基因的相似，支持 ABC 模型可以扩展到水稻的观点。为了阐明草不育器官（如浆片、外稃和内稃）与双子叶植物花器官之间的进化关系，我们表达了 RAG，一种水稻（Oryza sativa L.） AGAMOUS (AG) 直向同源物，在肌动蛋白 I 启动子控制下的水稻植物中。由于 RAG 的异位表达，浆片同源转化为雄蕊。总共，在 18 个中观察到浆片向退化雄蕊器官的转化。在 26 个独立的转基因品系中，与浆片中发生的几乎完全转化相反，没有一个转基因植物在内稃或内稃中表现出任何形态变化。我们的结果证实了浆片相当于双子叶植物花瓣的预测，并且 ABC 模型至少可以应用于水稻的浆片和雄蕊的器官规格。 papea 或引理提出了将 ABC 模型简单应用于浆片外结构可能无效的可能性。