Qiu Huan, Yoon Hwan Su, Bhattacharya Debashish
Department of Biological Sciences, Sungkyunkwan University, Suwon, South Korea.
PLoS Curr. 2016 Dec 2;8:ecurrents.tol.7b037376e6d84a1be34af756a4d90846. doi: 10.1371/currents.tol.7b037376e6d84a1be34af756a4d90846.
Red algae comprise an anciently diverged, species-rich phylum with morphologies that span unicells to large seaweeds. Here, leveraging a rich red algal genome and transcriptome dataset, we used 298 single-copy orthologous nuclear genes from 15 red algal species to erect a robust multi-gene phylogeny of Rhodophyta. This tree places red seaweeds (Bangiophyceae and Florideophyceae) at the base of the mesophilic red algae with the remaining non-seaweed mesophilic lineages forming a well-supported sister group. The early divergence of seaweeds contrasts with the evolution of multicellular land plants and brown algae that are nested among multiple, unicellular or filamentous sister lineages. Using this novel perspective on red algal evolution, we studied the evolution of the pathways for isoprenoid biosynthesis. This analysis revealed losses of the mevalonate pathway on at least three separate occasions in lineages that contain Cyanidioschyzon, Porphyridium, and Chondrus. Our results establish a framework for in-depth studies of the origin and evolution of genes and metabolic pathways in Rhodophyta.
红藻是一个古老分化、物种丰富的门类，其形态范围从单细胞到大型海藻。在这里，利用丰富的红藻基因组和转录组数据集，我们使用来自15种红藻物种的298个单拷贝直系同源核基因构建了一个强大的红藻多基因系统发育树。这棵树将红海藻（红毛菜纲和真红藻纲）置于嗜温红藻的基部，其余非海藻嗜温谱系形成一个得到有力支持的姐妹群。海藻的早期分化与多细胞陆地植物和褐藻的进化形成对比，后者嵌套在多个单细胞或丝状姐妹谱系之中。利用这种关于红藻进化的新观点，我们研究了类异戊二烯生物合成途径的进化。该分析揭示了在包含蓝氏藻属、紫球藻属和角叉菜属的谱系中，甲羟戊酸途径至少在三个不同场合出现了丢失。我们的结果为深入研究红藻中基因和代谢途径的起源与进化建立了一个框架。
