Plant Genetics, Institute for Water and Wetland Research, Radboud University Nijmegen, 6525AJ Nijmegen, The Netherlands.
Plant Cell. 2012 Jun;24(6):2305-17. doi: 10.1105/tpc.112.097030. Epub 2012 Jun 15.
According to the ABC(DE) model for flower development, C-genes are required for stamen and carpel development and floral determinacy, and D-genes were proposed to play a unique role in ovule development. Both C- and D-genes belong to the AGAMOUS (AG) subfamily of MADS box transcription factors. We show that the petunia (Petunia hybrida) C-clade genes PETUNIA MADS BOX GENE3 and FLORAL BINDING PROTEIN6 (FBP6) largely overlap in function, both in floral organ identity specification and floral determinacy, unlike the pronounced subfunctionalization observed in Arabidopsis thaliana and snapdragon (Antirrhinum majus). Some specialization has also evolved, since FBP6 plays a unique role in the development of the style and stigma. Furthermore, we show that the D-genes FBP7 and FBP11 are not essential to confer ovule identity. Instead, this function is redundantly shared among all AG members. In turn, the D-genes also participate in floral determinacy. Gain-of-function analyses suggest the presence of a posttranscriptional C-repression mechanism in petunia, most likely not existing in Arabidopsis. Finally, we show that expression maintenance of the paleoAPETALA3-type B-gene TOMATO MADS BOX GENE6 depends on the activity of C-genes. Taken together, this demonstrates considerable variation in the molecular control of floral development between eudicot species.
根据花发育的 ABC(DE)模型，C 基因对于雄蕊和心皮发育以及花的决定是必需的，而 D 基因被认为在胚珠发育中发挥独特作用。C 和 D 基因都属于 AGAMOUS (AG) 亚家族的 MADS 框转录因子。我们表明，矮牵牛（Petunia hybrida）的 C 类基因 PETUNIA MADS BOX GENE3 和 FLORAL BINDING PROTEIN6 在功能上基本重叠，在花器官身份特化和花的决定中都是如此，这与拟南芥和金鱼草（Antirrhinum majus）中观察到的明显的亚功能化不同。也进化出了一些特化，因为 FBP6 在花柱和柱头的发育中发挥了独特的作用。此外，我们表明，D 基因 FBP7 和 FBP11 对于赋予胚珠身份不是必需的。相反，这个功能在所有 AG 成员之间是冗余共享的。反过来，D 基因也参与花的决定。功能获得分析表明，矮牵牛中存在一种转录后 C 抑制机制，而这种机制在拟南芥中可能不存在。最后，我们表明，古 APETALA3 型 B 基因 TOMATO MADS BOX GENE6 的表达维持依赖于 C 基因的活性。综上所述，这表明在真双子叶植物物种之间，花发育的分子调控存在相当大的差异。
