论文部分内容阅读
细胞色素P450还原酶(cytochrome P450 reductase,CPR)在植物的生长、发育、天然产物的合成和抵御外界刺激的过程中发挥重要作用.本研究通过利用12种植物的36个CPR基因,运用CodonW软件分析密码子的偏好性指标,并分别运用SPSS和MEGA5.0软件进行密码子偏好性和基因聚类分析.结果显示,单子叶植物和双子叶植物CPR基因的有效密码子数(effective number of codons,ENC)范围分别为52.92～58.17和46.85～53.58,密码子偏好性较弱.全部CPR基因位点在ENC绘图中均偏离ENC期望曲线,其密码子偏好性主要是受自然选择压力的影响.单子叶植物和双子叶植物CPR基因对同义密码子的偏好性存在差异;同种植物不同CPR基因的密码子偏好性也不同.在基于基因同义密码子相对使用度(relative synonymous codon usage,RSCU)的聚类中,单子叶植物CPR基因和双子叶植物CPR基因分别聚为一支,更接近于12种植物的传统系统分类,反映了物种的进化关系,可以作为物种系统发育分析的重要补充.在基于基因编码序列(coding sequence,CDS)的系统进化树中,同种植物的CPR基因分别聚到两个支上,一定程度上反映了CPR基因的分类和功能.本研究结果从密码子偏好性和蛋白质水平上说明同种植物的不同CPR基因存在功能与进化差异,为植物CPR基因的分类与演化、功能预测与表达以及植物育种研究奠定了基础.“,”Cytochrome P450 reductase (CPR) plays an important role in plant growth,development,biosynthesis of natural compounds and protection against external stimulants.Based on thirty-six CPR genes in twelve plants from GenBank,codon usage bias was analyzed by CodonW software,and cluster analysis based on gene codon and coding sequence was performed with SPSS and MEGA5.0 respectively.The effective number of codons (ENC) of CPR genes in monocotyledon and dicotyledon ranged from 52,92 to 58,17 and 46.85 to 53,58 respectively,indicating that codon usage bias of plant CPR genes was weak.The ENC-plot revealed that all CPR genes diverged from the ENC expectation curve,indicating that codon usage bias of plant CPR genes was mainly affected by natural selection pressure.The synonymous codon bias of CPR genes was different between monocotyledon and dicotyledon,and also was of difference even from the same plant.Based on the relative synonymous codon usage (RSCU),the CPR genes in monocotyledon and in dicotyledon were clustered together respectively,which was closer to the traditional classification of twelve plants,reflected the evolution relationship of species,and could be used as a supplementary of phylogenetic analysis.While in the phylogenetic tree based on the coding sequence,CPR genes from the same species were clustered into two groups,which could be used for gene classification and function prediction.In this study,codon usage bias and cluster analysis of plant CPR genes were investigated to facilitate further research in gene classification and evolution,gene function prediction and protein expression,and plant breeding.