目的 分析药用植物富民枳Poncirus polyandra叶绿体基因组蛋白编码基因密码子使用模式及影响因素。方法 以富民枳叶绿体基因组53个蛋白编码基因为材料，利用CodonW软件、CUSP在线程序和R语言等整理并分析基因密码子使用偏性参数和核苷酸组成。结果 富民枳叶绿体基因组密码子各位置GC含量不同，偏好以A/U结尾；有效密码子数（effective number of codon，ENC）介于39.79～59.37，密码子偏好性较弱；密码子第3位碱基GC₃和ENC之间呈显著正相关；影响因素绘图分析结果表明自然选择对密码子使用模式有重要影响，共确定了12个最优密码子，且均偏向于A/U结尾。结论 富民枳叶绿体基因组密码子第3位碱基偏向使用A或U结尾，密码子偏性受自然选择影响最大，同时还受到突变等因素的共同影响。

Objective To investigate codon usage patterns and influencing factors in the chloroplast genome of Poncirus polyandra. Methods The 53 protein-coding genes of the P. polyandra chloroplast genome were used as materials to organize and analyze the codon usage patterns and nucleotide composition using CodonW software, CUSP online program and R language. Results The results showed that the GC content of the codons in the chloroplast genome of P. polyandra varied in each position, and the preference ended with A/U; The ENC value ranged from 39.79 to 59.37, and the codon usage bias was weak; There was a significant positive correlation between the third codon base GC₃ and ENC, and the codon usage bias was correlated with the third base. The results of neutral mapping analysis, parity preference analysis and effective codon mapping analysis showed that natural selection had an important influence on codon usage patterns, and the 12 optimal codons further proved that codon usage bias ended in A/U. Conclusion The third codon base of P. polyandra chloroplast genome codon is preferred to end in A/U. Codon usage bias is most affected by natural selection and is also affected by a combination of mutations and other factors.

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