Evolutionary analyses of TCP genes in Ranunculales

TCP transcription factors play a role in a large number of developmental processes and are at the crossroads of numerous hormonal biosynthetic and signaling pathways. The complete repertoire of TCP genes has already been characterized in several plant species, but not in any species of early diverging eudicots. We focused on the order Ranunculales because of its phylogenetic position as sister group to all other eudicots and its important morphological diversity. We characterized the full set of TCP transcripts in Nigella damascena (Ranunculaceae) and found that they are the orthologs of the TCP genes previously identified from the fully sequenced genome of Aquilegia coerulea. Phylogenetic analyses combined with the identification of conserved amino acid motifs suggest that six paralogous genes of class I TCP transcription factors were present in the common ancestor of angiosperms. We highlight independent duplications in core eudicots and Ranunculales within the class I and class II subfamilies, resulting in different numbers of paralogs within the main subclasses of TCP genes.

TCP转录因子（TCP transcription factors）参与诸多植物发育进程，同时亦是众多激素生物合成与信号通路的关键交汇点。目前已有多个植物物种的TCP基因完整集合得到系统鉴定，但早期分化真双子叶植物类群中尚无相关研究报道。本研究聚焦毛茛目（Ranunculales），因其系统发育位置为其他所有真双子叶植物的姊妹群，且具备显著的形态多样性。我们对毛茛科黑种草（Nigella damascena）中的全套TCP转录本完成了系统鉴定，发现其均为此前从全基因组测序完成的耧斗菜（Aquilegia coerulea）中鉴定得到的TCP基因直向同源基因。结合系统发育分析与保守氨基酸基序鉴定结果，本研究证实被子植物的共同祖先中存在6个I类TCP转录因子旁系同源基因。本研究同时揭示，I类与II类TCP亚家族在核心真双子叶植物与毛茛目中各自发生了独立的基因复制事件，最终导致TCP基因主要亚类的旁系同源基因数量存在差异。