红皮柳扩展蛋白基因家族的全基因组鉴定与分析

Genome Identification and Analysis of the Expansin Genes Family in Salix purpurea

扩展蛋白作为一种细胞壁松弛蛋白,参与了植物的生长发育和抗性过程,在植物基因组中具有不可或缺的作用。本研究依据已经测序的红皮柳基因组数据,鉴定了34个扩展蛋白基因,隶属于4个不同的亚家族,分布在14条染色体上。蛋白理化特征分析发现,多数扩展蛋白表现偏碱性,脂溶指数较高,蛋白结构稳定性较好。亚家族内的成员序列保守性更强,氨基酸一致率介于34.2%~99.4%之间,而不同亚家族间成员的氨基酸一致率介于15.0%~39.8%之间。亚家族内的基因外显子-内含子结构模式相似,亚家族间的基因结构组成存在明显差异。密码子使用分析发现,红皮柳扩展蛋白基因具有5个高频密码子,自然选择对密码子使用偏性影响较大。共线性分析显示,红皮柳扩展蛋白基因的分化与柳树进化过程中的基因组倍性事件有关。研究结果有助于理解扩展蛋白基因在柳树生长发育及进化中的地位,也为深入研究柳树扩展蛋白基因功能提供了参考。

Expansin is an indispensable cell wall protein, involved in plant growth and resistance to stress. Based on the sequencing genome data, a total of 34 expansin genes were identified on 14 chromosomes in Salix purpurea,which were grouped into 4 subfamilies. The analysis of the physicochemical properties showed that most expansin proteins were in weakly alkaline, had a higher aliphatic index and more stable protein structure. The gene sequence was more conservative among the members in the same subfamily with the amino acid identity between 34.2% and99.4%, while that was between 15.0% and 39.8% among the members in the different subfamilies. Also, the same subfamily genes had similar exon-intron structures, but the different subfamily genes showed that much differently.The codon usage analysis revealed that there are 5 high-frequency codons in Salix purpurea expansin genes. The codon usage bias was much affected by natural selection. The synteny analysis showed that the expansin genes divided in corresponce to whole-genome duplication events in willow. The results here would help us to understand well the role and status of expansin genes in the growth and development of Salix purpurea. It will be helpful for further study on the expansins functions.