Dipp-Álvarez Melissa, Cruz-Ramírez Alfredo
Molecular and Developmental Complexity Group, Unidad de Genómica Avanzada, Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Guanajuato, Mexico.
Front Plant Sci. 2019 Jan 29;10:17. doi: 10.3389/fpls.2019.00017. eCollection 2019.
Comparative genomics has revealed that members of early divergent lineages of land plants share a set of highly conserved transcription factors (TFs) with flowering plants. While gene copy numbers have expanded through time, it has been predicted that diversification, co-option, and reassembly of gene regulatory networks implicated in development are directly related to morphological innovations that led to more complex land plant bodies. Examples of key networks have been deeply studied in , such as those involving the AINTEGUMENTA (ANT) gene family that encodes AP2-type TFs. These TFs play significant roles in plant development such as the maintenance of stem cell niches, the correct development of the embryo and the formation of lateral organs, as well as fatty acid metabolism. Previously, it has been hypothesized that the common ancestor of mosses and vascular plants encoded two ANT genes that later diversified in seed plants. However, algae and bryophyte sequences have been underrepresented from such phylogenetic analyses. To understand the evolution of ANT in a complete manner, we performed phylogenetic analyses of ANT protein sequences of representative species from across the Streptophyta clade, including algae, liverworts, and hornworts, previously unrepresented. Moreover, protein domain architecture, selection analyses, and regulatory elements prediction, allowed us to propose a scenario of how the evolution of ANT genes occurred. In this study we show that a duplication of a preANT-like gene in the ancestor of embryophytes may have given rise to the land plant-exclusive basalANT and euANT lineages. We hypothesize that the absence of euANT-type and basalANT-type sequences in algae, and its presence in extant land plant species, suggests that the divergence of pre-ANT into basal and eu-ANT clades in embryophytes may have influenced the conquest of land by plants, as ANT TFs play important roles in tolerance to desiccation and the establishment, maintenance, and development of complex multicellular structures which either became more complex or appeared in land plants.
比较基因组学研究表明，早期分化的陆地植物谱系成员与开花植物共享一组高度保守的转录因子（TFs）。虽然基因拷贝数随时间增加，但据预测，参与发育的基因调控网络的多样化、共选择和重新组装与导致陆地植物形态更复杂的形态创新直接相关。关键网络的例子已在[具体研究对象]中得到深入研究，例如涉及编码AP2型TFs的AINTEGUMENTA（ANT）基因家族的网络。这些TFs在植物发育中发挥重要作用，如维持干细胞龛、胚胎的正常发育和侧生器官的形成，以及脂肪酸代谢。此前，有人推测苔藓和维管植物的共同祖先编码了两个ANT基因，后来在种子植物中发生了分化。然而，此类系统发育分析中藻类和苔藓植物序列的代表性不足。为了全面了解ANT的进化，我们对链形植物进化枝中代表性物种的ANT蛋白序列进行了系统发育分析，包括之前未被纳入的藻类、地钱和角苔。此外，蛋白质结构域结构、选择分析和调控元件预测使我们能够提出ANT基因进化过程的设想。在本研究中，我们表明胚胎植物祖先中一个类似preANT的基因的复制可能产生了陆地植物特有的basalANT和euANT谱系。我们推测，藻类中不存在euANT型和basalANT型序列，而现存陆地植物物种中存在这些序列，这表明胚胎植物中pre-ANT分化为basal和eu-ANT分支可能影响了植物对陆地的征服，因为ANT转录因子在耐干燥性以及复杂多细胞结构的建立、维持和发育中发挥重要作用，而这些结构在陆地植物中要么变得更加复杂，要么首次出现。
