樟叶槭叶绿体基因组序列密码子偏性分析

为确定槭属樟叶槭叶绿体基因组密码子使用模式和原因，通过对樟叶槭叶绿体基因组中筛选的53条基因序列进行中性绘图、ENC-plot与PR2-plot等分析，确定樟叶槭叶绿体基因组密码子偏好性基本特征与其最佳密码子的构成，分析过程中主要使用Codon W 1.4.2、CUSP、R等软件。结果表明，共有28个密码子，且均以A或U结尾，说明樟叶槭叶绿体基因组密码子对A/U结尾偏好。密码子第1、2和3位上的GC平均含量分别为47.04%、39.56%与29.66%,GC平均含量为38.75%,ENC范围在37.60～57.16,其中ENC小于45的只有11个，表明樟叶槭叶绿体基因组密码子存在较弱的偏性。PR2-plot绘图分析显示多数位点偏离中心，落于右下方位置；最优密码子确定为UGU、CAA、GUU等15个最优密码子。该结果为槭属植物叶绿体基因组进化与转化体系中载体构建研究提供参考依据。

Codon Usage Bias of Acer cinnamomifolium Chloroplast Genome

To determine the codon usage pattern of chloroplast genome in Acer cinnamomifolium,Codon W 1.4.2,cusp and R software were used to analyze 53 selected protein coding sequences,and codons were analyzed by neutral plotting,ENC-plot,PR2-plot and optimal codon.The results showed that there were 28 codons with RSCU>1,all ending in A/U,indicating that the synonymous codons in the chloroplast genome and A/U ending bias of A.cinnamomifolium.The average content of GC at the first,second and third positions of codon were 47.04%,39.56% and 29.66%,respectively,and the average content of all GC was 38.75%.The range of ENC (effective number of codon) value ranged from 37.60 to 57.16,and 42 genes ENC were greater than 45,indicating weak bias in A.cinnamomifolium chloroplast genome.PR2-plot analysis showed that the number of genes located in the lower right corner of PR2-plot ichnography was the largest.The optimal codons were determined as UGU,CAA,GUU and other 12 optimal codons.The results will take some bases for future studies on vector construction in chloroplast genome evolution and transformation system of Acer genus.