Pabón-Mora Natalia, Madrigal Yesenia, Alzate Juan F, Ambrose Barbara A, Ferrándiz Cristina, Wanke Stefan, Neinhuis Christoph, González Favio
Instituto de Biología, Universidad de Antioquia, Medellín, 050010, Colombia.
Technische Universität Dresden, Institut für Botanik, Dresden, 01062, Germany.
New Phytol. 2020 Oct;228(2):752-769. doi: 10.1111/nph.16719. Epub 2020 Jul 2.
Controlled spatiotemporal cell division and expansion are responsible for floral bilateral symmetry. Genetic studies have pointed to class II TCP genes as major regulators of cell division and floral patterning in model core eudicots. Here we study their evolution in perianth-bearing Piperales and their expression in Aristolochia, a rare occurrence of bilateral perianth outside eudicots and monocots. The evolution of class II TCP genes reveals single-copy CYCLOIDEA-like genes and three paralogs of CINCINNATA (CIN) in early diverging angiosperms. All class II TCP genes have independently duplicated in Aristolochia subgenus Siphisia. Also CIN2 genes duplicated before the diversification of Saruma and Asarum. Sequence analysis shows that CIN1 and CIN3 share motifs with Cyclin proteins and CIN2 genes have lost the miRNA319a binding site. Expression analyses of all paralogs of class II TCP genes in Aristolochia fimbriata point to a role of CYC and CIN genes in maintaining differential perianth expansion during mid- and late flower developmental stages by promoting cell division in the distal and ventral portion of the limb. It is likely that class II TCP genes also contribute to cell division in the leaf, the gynoecium and the ovules in A. fimbriata.
受控的时空细胞分裂和扩展决定了花的两侧对称性。遗传学研究表明，II类TCP基因是模式核心真双子叶植物中细胞分裂和花模式形成的主要调节因子。在这里，我们研究了它们在有花被的胡椒目中的进化以及它们在马兜铃属中的表达，马兜铃属是真双子叶植物和单子叶植物之外罕见的具有两侧花被的植物。II类TCP基因的进化揭示了早期分化被子植物中的单拷贝类CYCLOIDEA基因和三个CINCINNATA（CIN）旁系同源基因。所有II类TCP基因在马兜铃属Siphisia亚属中都独立复制。此外，CIN2基因在细辛属和马蹄香属分化之前就已复制。序列分析表明，CIN1和CIN3与细胞周期蛋白共享基序，而CIN2基因已失去miRNA319a结合位点。对马兜铃花中II类TCP基因所有旁系同源基因的表达分析表明，CYC和CIN基因通过促进花被边缘远端和腹侧部分的细胞分裂，在花发育的中后期维持花被的差异扩展中发挥作用。II类TCP基因可能也对马兜铃叶、雌蕊和胚珠中的细胞分裂有贡献。
