| 摘要: |
| 淡水红藻是藻类植物进化中的一个重要类群，其中最主要的类群是串珠藻目。核酮糖1，5二磷酸羧化酶/加氧酶（Rubisco）是一种既负责碳同化又引发光呼吸，在植物光合作用中起重要作用的酶，其催化固定CO2的活性中心位于Rubisco大亚基，由叶绿体rbcL基因编码。为了探究串珠藻目植物适应特殊生存环境的分子水平机制，本文选取了串珠藻目及一些相近类群淡水红藻的rbcL基因39条，利用PAML4.8软件，运行位点模型、分支模型及分支-位点模型，对选取类群的rbcL基因进行了适应性进化分析。结果表明：（1）通过最大似然法构建的系统发育树显示，所有内类群聚集为6个分支，其中，分支A为暗紫红毛菜，分支B为胶串珠藻，分支C为扁圆串珠藻，后验概率同样为100%，分支D为熊野藻属，分支E为连珠藻属，分支F为弧形西斯藻；（2）分支-位点模型中，在3个分支中分别鉴定出350S、277L和280L为正选择位点；（3）在构建出的Rubisco大亚基的参考三维模型中，277L和280L位于Rubisco大亚基羧基末端保守的8个α螺旋和8个β片层构成的α/β桶状结构域中第7个α螺旋和第7个β片层之间的loop结构上，350S位于羧基末端邻近α/β桶状结构域的一个α螺旋上。研究结果一方面显示了基于ω比值检验基因适应性进化的准确性和有效性，另一方面也揭示了串珠藻目植物rbcL基因确实发生了适应性进化，对串珠藻目适应特殊生存环境产生了有益的作用。 |
| 关键词: 串珠藻目 rbcL基因 适应性进化 |
| DOI：10.11693/hyhz20161200277 |
| 分类号:Q941 |
| 基金项目:国家自然科学基金项目，31670208号，31370239号。 |
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| ADAPTIVE EVOLUTIONARY ANALYSIS ON rbcL GENE OF BATRACHOSPERMALES |
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GONG Chao-Yan, NAN Fang-Ru, FENG Jia, LÜ Jun-Ping, LIU Qi, XIE Shu-Lian
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School of Life Science, Shanxi University, Taiyuan 030006, China
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| Abstract: |
| Freshwater red algae are an important lineage in algal evolution. Batrachospermales is an order with the most species. Ribulose-1,5 bisphosphate carboxylase/oxygenase (Rubisco) is an enzyme responsible for both carbon assimilation and photorespiration, and plays an important role in plant photosynthesis. The Rubisco large subunit containing active sites for catalyzing CO2 fixation, is encoded by chloroplast rbcL gene. To explore the molecular mechanism of algal adaption to special living environment, 39 rbcL genes of Batrachospermales and other relative taxa were selected to analyze the adaptive evolution. Using software PAML4.8, the site model, branch model, and branch-site model were tested. The results show that (1) in the phylogenetic tree constructed by the maximum likelihood method, all the internal groups cluster into six branches, i.e., Cluster A is Bangia atropurpurea, B is Batrachospermum gelatinosum, C is B. helminthosum, D is the genus Kumanoa, E is the genus Sirodotia, and F is Sheathia arcuata; (2) 350S, 277L, and 280L are identified as positive selection sites on three branches in the branch-site model; (3) in the reference three-dimensional model of Rubisco large subunit, 277L and 280L are located in a loop between the 7th α helix and the 7th β sheet of the conserved α/β-barrel domain that consists of 8 α-helices and 8 β-sheets at the C-terminus, and 350S is located on an α helix in the C-terminus adjacent to the α/β-barrel domain. Therefore, the results demonstrated the accuracy and effectiveness of examining the adaptive evolution of gene based on ω ratio, and revealed that the rbcL gene has undergone adaptive evolution, which has been beneficial to Batrachospermales for the adaption to the special living environment. |
| Key words: Batrachospermales rbcL gene adaptive evolution |
