Kramer Elena M, Jaramillo M Alejandra, Di Stilio Verónica S
Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.
Genetics. 2004 Feb;166(2):1011-23. doi: 10.1534/genetics.166.2.1011.
Members of the AGAMOUS (AG) subfamily of MIKC-type MADS-box genes appear to control the development of reproductive organs in both gymnosperms and angiosperms. To understand the evolution of this subfamily in the flowering plants, we have identified 26 new AG-like genes from 15 diverse angiosperm species. Phylogenetic analyses of these genes within a large data set of AG-like sequences show that ancient gene duplications were critical in shaping the evolution of the subfamily. Before the radiation of extant angiosperms, one event produced the ovule-specific D lineage and the well-characterized C lineage, whose members typically promote stamen and carpel identity as well as floral meristem determinacy. Subsequent duplications in the C lineage resulted in independent instances of paralog subfunctionalization and maintained functional redundancy. Most notably, the functional homologs AG from Arabidopsis and PLENA (PLE) from Antirrhinum are shown to be representatives of separate paralogous lineages rather than simple genetic orthologs. The multiple subfunctionalization events that have occurred in this subfamily highlight the potential for gene duplication to lead to dissociation among genetic modules, thereby allowing an increase in morphological diversity.
MIKC型MADS-box基因的AGAMOUS（AG）亚家族成员似乎控制着裸子植物和被子植物生殖器官的发育。为了解该亚家族在开花植物中的进化情况，我们从15种不同的被子植物物种中鉴定出了26个新的AG样基因。在一个包含AG样序列的大型数据集中对这些基因进行系统发育分析表明，古老的基因复制对该亚家族的进化形成至关重要。在现存被子植物辐射分化之前，一次事件产生了胚珠特异性的D谱系和特征明确的C谱系，其成员通常促进雄蕊和心皮的特征形成以及花分生组织的确定性。C谱系随后的复制导致了旁系同源基因亚功能化的独立实例，并维持了功能冗余。最值得注意的是，拟南芥的功能同源基因AG和金鱼草的PLENA（PLE）被证明是不同旁系同源谱系的代表，而不是简单的基因直系同源物。该亚家族中发生的多个亚功能化事件突出了基因复制导致遗传模块间解离的潜力，从而增加了形态多样性。
