Data from: Evolution of floral diversity: genomics, genes and gamma

A salient feature of flowering plant diversification is the emergence of a novel suite of floral features coinciding with the origin of the most species-rich lineage, Pentapetalae. Advances in phylogenetics, developmental genetics and genomics, including new analyses presented here, are helping to reconstruct the specific evolutionary steps involved in the evolution of this clade. The enormous floral diversity among Pentapetalae appears to be built on a highly conserved ground plan of five-parted (pentamerous) flowers with whorled phyllotaxis. By contrast, lability in the number and arrangement of component parts of the flower characterize the early-diverging eudicot lineages subtending Pentapetalae. The diversification of Pentapetalae also coincides closely with ancient hexaploidy, referred to as the gamma whole-genome triplication, for which the phylogenetic timing, mechanistic details and molecular evolutionary consequences are as yet not fully resolved. Transcription factors regulating floral development often persist in duplicate or triplicate in gamma-derived genomes, and both individual genes and whole transcriptional programmes exhibit a shift from broadly overlapping to tightly defined expression domains in Pentapetalae flowers. Investigations of these changes associated with the origin of Pentapetalae can lead to a more comprehensive understanding of what is arguably one of the most important evolutionary diversification events within terrestrial plants.有花植物演化多样化的一个显著特征，是伴随物种最丰富的支系——五数花类群(Pentapetalae)起源而出现的一套全新花部特征。系统发育学、发育遗传学与基因组学领域的进展，包括本文所呈现的新分析，正助力我们重构该支系演化所涉及的具体演化步骤。五数花类群内部极高的花部多样性，似乎构建于一套高度保守的五数花（pentamerous）、具轮状叶序的基础构型之上。与之形成鲜明对比的是，作为五数花类群基部类群的早期分化真双子叶植物支系，其花部组成单元的数量与排列具有显著可塑性。五数花类群的多样化进程，还与古老的六倍化事件——即γ全基因组三倍化(gamma whole-genome triplication)——高度同步；目前该事件的系统发育时间节点、分子机制细节及演化后果尚未完全阐明。调控花发育的转录因子在源自该全基因组三倍化事件的基因组中，常以重复或三倍拷贝的形式留存；且在五数花类群的花器官中，单个基因乃至整个转录程序均呈现出从广泛重叠的表达域向严格限定的表达域转变的特征。针对与五数花类群起源相关的上述变化开展研究，将有助于我们更全面地理解这一可以说是陆生植物中最重要的演化多样化事件之一。