八氢番茄红素脱氢酶(PDS)基因分子进化特征

Molecular Evolutionary Characterization of Phytoene Desaturase(PDS) Genes

对来自蓝藻、绿藻和高等植物中的pds基因用最大似然法进行了系统发育分析,来估算pds基因在进化过程中的正选择位点。通过位点模型和分支-位点模型分别对PDS不同位点和不同分支中的位点进行正选择作用的估算。结果发现,pds基因的适应性进化主要发生在系统发育树的不同分支上。在绿藻分支中,有7.9%位点受到正选择作用;在高等植物分支中,有6.1%位点受到正选择作用;在蓝藻分支中,有2.6%位点受到正选择作用。这些正选择位点的识别,可以为PDS活性研究提供重要的线索。

Phytoene desaturase is one of the most important enzymes necessary for the biosynthesis of carotenoids in some cyanobacteria, green alga and plants. In this study, we have employed the maximum likelihood method to detect evidence of positive selection on PDS protein. Site model and branch-site model were used to test positive selection sites among sites and among lineages. The results showed that the adaptive evolution mostly occurred in some lineages. Along green algal branch, 7.9 % of sites are under positive selection. Furthermore, 6.1% of the codons along high plant branch are subject to positive selection. Along cyanobacterial branch, fewer codons（about 2.6%） were detected for positive selection. The sites identified to be under positive selection would be candidates to test for the functional analysis of PDS.