天料木属植物叶绿体基因组密码子使用偏性分析

Analysis of Codon Usage Bias in Chloroplast Genome of Homalium

为揭示天料木属4种植物叶绿体基因组密码子偏性特征及偏性特征的影响因素,对4种植物叶绿体基因组进行分析,结果显示:天料木属4种植物叶绿体基因组GC含量均不足50%;GC12与GC3双尾检验均呈显著相关(p<0.05);超过60%的基因ENc实际值围绕在期望值曲线附近;密码子第3位均存在T/C偏倚;第1轴与CAI值均呈现不同程度的相关性;斯里兰卡天料木、广南天料木和狭叶天料木的亲缘关系较天料木更近。因此得出:突变压力在影响4种植物叶绿体基因组密码子偏性因素中比重较大,但自然选择等因素仍发挥着主要作用。天料木属4种植物有13个相同的最优密码子UUU、UUA、UUG、AUU、GUA、CCU、ACU、GCU、CAA、AAA、GAA、UGU、GGU。但天料木多出4个:GUU、UCU、CCA、AGU。天料木叶绿体基因组密码子偏性不同于其他天料木属3种植物。

In order to reveal the codon bias characteristics and main influencing factors of the chloroplast genomes of four species of Homalium.The analysis of the coding sequences of the chloroplast genomes of four species of Homalium showed that:the GC content of the chloroplast genomes of the four plants in the Homalium was less than 50%;GC12 was significantly correlated with GC3(P<0.05);the ENc of more than 60%was around the expected curve;T/C bias existed in the third codon;The first axis is correlated with the CAI;The relationship between Homalium ceylanicum,Homalium paniculiflorum and Homalium stenophyllum is closer than that of Homalium cochinchinense.It is concluded that mutation pressure accounts for a large proportion of factors affecting the codon bias of the chloroplast genomes of the four Homalium plant species,but natural selection and other factors still play a major role.There are 13 identical optimal codons UUU,UUA,UUG,AUU,GUA,CCU,ACU,GCU,CAA,AAA,GAA,UGU,GGU in the four plants of Homalium.However,there are four more optimal codes for Homalium cochinchinense:GUU,UCU,CCA and AGU.The codon bias of the chloroplast genome of Homalium cochinchinense is different from the other three species of Homalium.