茶树抗寒调控转录因子ICE1密码子偏性分析

Analysis of Codon Bias of the Cold Regulated Transcription Factor ICE1 in Tea Plant

运用CHIPS、CUSP和CodonW软件程序分析自主克隆的茶树(Camellia sinensis)ICE1(GenBank登录号JX029153)的密码子的偏性,并与茶树基因组及萝卜等7种植物的ICE1密码子偏性进行比较。结果表明,茶树ICE1偏好于以A/T结尾的密码子;与茶树基因组密码子偏性相比,发现只有6种氨基酸密码子偏性完全一致。进一步研究发现ICE1的碱基组成在单子叶植株大麦与7种双子叶植物分化后发生了较大的变化。在聚类分析中,基于基因CDS序列的聚类不能正确反映物种间的进化关系,而基于密码子偏性参数相对密码子使用度(RSCU)的聚类更适合作为系统发育分析的参考。与3种外源受体密码子使用频率比较发现,与大肠杆菌基因组密码子使用频率差值较大的有25个,与酵母基因组差值较大的有15个,与拟南芥基因组差值较大的有10个,这预示着ICE1在拟南芥中的表达效率最高,若要在其他外源受体中进行高效表达,尚需对其密码子进行优化。

In this study the coding sequence of the ICE1 （GenBank Accession No. JX029153 ） in tea plant （Camellia sinensis） were analyzed with CodonW, CHIPS （Condon heterozygosity in a protein coding sequence） and CUSP （Create a codon usage table） programs, while compared with the genome of tea plant and 1CE1 from 7 plant species. The results showed that 1CE1 of tea plant was bias toward the synonymous codons with A and T. Compared with the codon usages of tea genome, the consequence indicated that only six kinds of amino acid codon bias was exactly the same. Further studies found that the 1CE1 bases composition had greatly changed after monocotyledonous and dicotyledonous plants differentiating. The cluster tree based on the relative synonymous codon usage（RSCU）could not reveal the evolutional relations among the 8 plant species, whereas that based on the relative synonymous codon usage （RSCI3） could reveal their evolutional relationship much better. There are 25 codons showing distinct usage differences between ICE1 of tea plant and genome ofEscherichia coli, 15 between 1CE1 of tea plant and genome of yeast, 10 between ICE1 of tea plant and genome of Arabidopsis thaliana. Therefore, the Arabidopsis thaliana expression system may be more suitable for the expression of ICE1 of tea plant.