Evolutionary study of peta-like organ in Angiosperms

花的形态发生模式，即ABC模式，是目前对突变花进行分子遗传学分析的结果，已被广泛接受。ABC模型也适用于水稻花，水稻花的结构与拟南芥花不同，似乎适用于大多数被子植物。凤眼莲花由3枚雄蕊和3枚心皮组成，无花被。但是，它们在花序的基部有一个白色花瓣状的器官，称为总苞，因为它们附着在花序的最低位置。本研究着重探讨了花瓣状器官的形成机制，特别是ABC模式是否参与了总苞的形成，或者是在不同的进化过程中获得的。因此，MADS-box基因已在H.心脏然后用定量RT-PCR和原位杂交检测各基因的表达。结果表明，在黑穗醋栗的总苞中观察到属于API组、PI组、AP 3组和SEP组的基因的表达。心脏至于这些基因表达的组合，已经变得很清楚，是必要的足够的决定器官的身份在拟南芥花瓣。这一结果表明，H。cordata与拟南芥花瓣具有相似的决定机制。

The morphogenesis model of the flower, which is called the ABC model, had been advocated and, is widely accepted as the result of molecular genetic analyzes of mutant flowers. The ABC model is also applicable to the flower of rice, which has a different structure from those of Arabidopsis, and is seems to be fit in most angiosperms.The flower of Houttuynia cordata consists of 3 stamens and 3 carpels, and have no perianth. But, they have a white petal-like organ at the base of the inflorescence ,which is called the involucral bract, because they are attached to the lowest position of inflorescence. In this study, we focused on mechanism of petal-like organ formation, especially whether the ABC model having participated in this involucral bract formation, or it had acquired with different evolution process. Thus, the MADS-box genes had been cloned and characterized in H. cordata. Then, expression of each gene was inspected by quantity RT-PCR and in situ hybridization. As a result, expression of the genes belonging to the API group, the PI group, the AP3 group and the SEP group had been observed in the involucral bract of the H. cordata. As for combination of these gene expressions, it has become clear to be necessary sufficient ones to determination of the organ identity of the petals in Arabidopsis thaliana. This result suggests the possibility that the petal-like bract of H. cordata has similar detemination mechanism to the petal of Arabidopsis.