Vertical adaptive radiation in ocean Prochlorococcus:Evolutionary implications of the Ch1 b/a ratio from molecular evidence  

作　　者：Song Qin Yinchu Wang 

机构地区：[1]Yantai Institute of Coastal Zone Research for Sustainable Development, Chinese Academy of Sciences, Yantai 264003, China [2]Graduate University of Chinese Academy of Sciences, Beijing 100049, China

出　　处：《Progress in Natural Science:Materials International》2009年第11期1561-1568,共8页自然科学进展·国际材料（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No.30670165);the Key Innovative Project of the Chinese Academy of Sciences (Grant Nos.KZCX2-YW-209 and KZCX2-YW- 216);the CAS/SAFEA International Partnership Program for Creative Research Teams.

摘　　要：Prochlorococcus is a marine cyanobacterium of global significance. Two ecotypes are adapted to either high-light （HL） or low-light （LL） conditions. The ratio between chlorophyll （Chl） a and b is a distinguishing characteristic of these two ecotypes. However, how this ratio evolved in Prochlorococcus during this ecotype differentiation remains unclear. Our analyses reveal that the ancestor of Prochlorococcus was typically low-light adapted. The LL ecotype showed a stagnant evolution, and the HL ecotype was recently diverged. There was an adaptive radiation after directional evolution in the Chl b/a ratio regulation. Recombination in chlorophyllide a oxygenase （CAO） and positive selection on Clp protease contributed to the directional evolution of Prochlorocoecus. The recombinant fragments of CAO were correlated with a large group of shared coevolving sites. Evidence of positive selection was found in both subunits of Clp. Chl bla ratio evolution, as annotated by molecular evidence, appears to be among the crucial reasons that explain how Prochloroeoccus has become the dominant photosynthetic organism in the ocean.Prochlorococcus 是全球意义的海洋的 cyanobacterium。二生态型被使适应任何一个热点(HL ) 或低光(LL ) 条件。在叶绿素(Chl ) 之间的比率 and b 是这二生态型的一个区分的特征。然而，这比率怎么在这生态型区别期间在 Prochlorococcus 演变，仍然保持不清楚。我们的分析表明 Prochlorococcus 的祖先典型地是低光的适应。LL 生态型显示出停滞进化，并且 HL 生态型最近被分叉。在在 Chl b/a 比率规定的方向性的进化以后有适应放射。在 chlorophyllide 的再结合 oxygenase (CAO ) 和 Clp 朊酶上的积极选择贡献了 Prochlorococcus 的方向性的进化。CAO 的 recombinant 碎片与分享的 coevolving 地点的一个大组一起被相关。积极选择的证据在 Clp 的两个子单元被发现。Chl b/a 比率进化由分子的证据注解了看起来在解释 Prochlorococcus 怎么在海洋成为了主导的光合的有机体的关键原因之中。

关 键 词：PROCHLOROCOCCUS Chl b/a ratio Adaptive evolution Trait evolution Ecotype differentiation 

分 类 号：Q945.11[生物学—植物学] Q111