念珠藻属植物nifH基因的适应性进化分析
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引用本文:王 捷,徐 羽,石 瑛,王清华,孟志龙,谢树莲.念珠藻属植物nifH基因的适应性进化分析[J].西北植物学报,2019,39(11):1961~1969
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作者单位
王 捷1,徐 羽1,石 瑛1*,王清华1,孟志龙1,谢树莲2 (1 太原师范学院 生物系山西晋中 030619 2 山西大学 生命科学学院太原 030006) 
基金项目:山西省“1331工程”重点创新团队建设计划(TD201718);
中文摘要:念珠藻(Nostoc)固氮过程关键在于固氮酶的催化,而固氮酶复合物中的铁蛋白(NifH)是由高度保守的nifH基因编码的,该基因是进化史上现存最古老的功能基因之一。该研究选取念珠藻属及近缘类群的nifH基因序列共40条,采用最大似然法构建系统发育树;运行PAML4.9软件,对nifH基因编码蛋白进行生物信息学分析,并使用分支模型、位点模型和分支 位点模型检测该基因的选择位点,探讨nifH基因的适应性进化特征。结果表明:(1) 最大似然树显示内类群中该研究物种共分为6个分支(A、B、C、D、E和F),其中D和E是2个大的分支,每个大分支中又各包含2个特殊的小分支A、F和B、C,其中F分支包含新疆古尔班通古特沙漠采集到的9株念珠藻,A分支包含F分支及该研究测定序列的4株葛仙米,B分支包含本研究测定序列的4株地皮菜和3株未定种的念珠藻,C分支包含NCBI数据库中下载的5株念珠藻、鱼腥藻序列和本研究测定序列的1株念珠藻。(2)在所分析的3种进化模型中,仅通过分支 位点模型检测出14个统计学上显著的正选择位点,即1F、2S、3S、4T、5A、6F、7F、8I、9S、10C、17I、27Y、29D和31R位点,表明念珠藻属植物的nifH基因发生了适应性变化,分支 位点模型是研究藻类基因适应性进化较好的模型。
中文关键词:念珠藻  nifH基因  分支模型  位点模型  分支 位点模型  适应性进化
 
Adaptive Evolutionary Analysis on nifH Gene of Nostoc
Abstract:Nitrogen fixation depends on the catalysis of nitrogenase in Nostoc. The nitrogenase iron protein NifH encoded by the highly conserved nifH gene, which is one of the oldest existing functional genes in the history of gene evolution. In this paper, 40 nifH gene sequences of Nostoc and the relative species group of cyanobacteria were selected, and the phylogenetic trees relied on these sequence data were constructed by maximum likelihood method. Then PAML4.9 software was used to analyze the bioinformatics of nifH gene coding proteins in Nostoc. Branch model, site model and branch site model were used to detect the selection sites of the nifH genes, and to explore the adaptive evolution characters of the nifH genes. Our results indicated that: (1) the phylogenetic tree with the maximum likelihood method showed that the inner group could be divided into six large branches (A, B, C, D, E and F), among which D and E are two big branches, and each big branch contains two special small branches A, F and B, C, among which F branch contains nine Nostoc collected from Gurbantonggute desert in Xinjiang, A branch contains F branch and four Nostoc sphaeroides and B branch contains four Nostoc commune and three Nostoc sp. in this study. The C branch contains five Nostoc and Anabaena sequences downloaded from NCBI database and one Nostoc of this study; (2) in the three evolutionary models analyzed, 14 significant positively selected sites such as 1F, 2S, 3S, 4T, 5A, 6F, 7F, 8I, 9S, 10C, 17I, 27Y, 29D and 31R were detected. Therefore, the results showed that the nifH genes have undergone adaptive evolution in Nostoc. Branch site model is a better model to study the adaptive evolution of algae genes.
keywords:Nostoc  nifH gene  branch model  site model  branch site model  adaptive evolution
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