目的 对五加科药用植物的鲨烯合酶（squalene synthase，SS）进行适应性进化分析。方法 利用PAML软件的分支模型、位点模型、分支-位点模型以及MEC模型、SLAC、FEL和REL等方法对五加科7种药用植物的23条SS基因进行适应性进化分析。结果 在PAML与MEC模型的分析中发现多数分支与位点处于较强的负选择下，未发现正选择位点；通过SLAC、FEL和REL分析同样显示存在大量的负选择位点，仅412P、413N、415K为正选择位点。结论 负选择对五加科SS基因起主导作用，而发现的412P、413N、415K位点可能与SS的活性有关。

Objective To analyze the adaptive evolution of squalene synthase (SS) in the medicinal plants of Araliaceae. Methods The adaptive evolutionary analysis of 23 SS genes of seven medicinal plants of Araliaceae was carried out by using the branch model, site model, branch-site model, MEC model, SLAC, FEL, and REL of PAML software. Results In the analysis of PAML and MEC models, most of the branches and loci were found to be under strong negative selection, and no positive selection sites were found. The analysis by SLAC, FEL, and REL also showed that there were a large number of negative selection sites, only 412P, 413N, and 415K were positive selection sites. Conclusion This indicates that negative selection plays a leading role in SS gene of Araliaceae. The 412P, 413N, and 415K sites found may be involved in the activity of SS.

R282.12

国家自然科学基金项目（31570683）；河北省教育厅资助科研项目（ZD2019075）；华北理工大学培育基金资助（SP201508）