忍冬属黄酮合成酶基因FNSⅡ密码子偏好性及进化分析

Codon Bias and Evolutionary Analysis of Lonicera Flavone Synthase Gene FNSⅡ

目的探讨忍冬属木犀草苷关键合成酶基因FNSⅡ在进化过程中形成的密码子使用模式及其与不同植物的亲缘关系,为实现木犀草苷异源高表达提供依据。方法利用Codon W、Clustal X、MEGA4.0及SPSS18.0软件,对23个不同物种的FNSⅡ基因及29条忍冬属FNSⅡ序列进行密码子偏好性和进化分析。结果植物FNSⅡ的平均有效密码子数(ENC)为52.29,表明该基因密码子偏好性较弱;ENC-Plot分析发现FNSⅡ基因密码子偏好性形成主要受突变压力的影响,但忍冬属FNSⅡ更多受到自然选择压力的影响。忍冬属FNSⅡ序列GC含量均值<50%,GC3s均值在50%左右,ENC均值为52.66,整体密码子偏好性较弱。基于FNSⅡ序列的系统进化聚类分析较相对同义密码子使用度(RSCU)聚类分析更符合传统的物种分类结果。酵母是忍冬FNSⅡ最佳外源表达系统,模式植物拟南芥、烟草均可作为忍冬FNSⅡ的遗传转化受体。结论忍冬属FNSⅡ序列表现出相似的密码子偏好性,可为忍冬属植物FNSⅡ基因的分类、演化与表达及植物育种研究提供依据。

Objective To explore the codon usage pattern in evolution process and the phylogenetic relationship among different plants of Lonicera galuteolin synthesis key enzyme gene FNSⅡ;To provide references for its high heterologous expression.Methods The softwares such as Codon W,Clustal X,MEGA 4.0,and SPSS 18.0 were employed to analyze the codon bias and evolutionary of FNSⅡgenes of 23 different species and 29 Lonicera FNSⅡsequences.Results The mean of effective number of codon(ENC)of FNSⅡwas 52.29,which illustrated weak codon bias;the ENC-Plot analysis demonstrated that the form of FNSⅡcodon bias in different species was mainly resulted by the mutation pressure,while nature selection was for most of the Lonicera FNSⅡgenes.The mean GC content of FNSⅡgenes was lower than 50%,the mean value of GC3s was approximately 50%,and its mean value of ENC was 52.66,which illustrated weak codon bias.Compared with the RSCU cluster analysis,the phylogenetic analysis result based on FNSⅡsequence was much more in accordance with the traditional taxonomy.Yeast was the most suitable heterologous expression system for Lonicera FNSⅡ.Meanwhile the model plants Arabidopsis and tobacco both could be used as genetic transformation receptors of the Lonicera FNSⅡ.Conclusion Lonicera FNSⅡshows similar codon bias.This study has laid a foundation for the classification,evolution and expression and plant breeding research of Lonicera FNSⅡgenes.