蒺藜苜蓿CIPK基因家族全基因组鉴定及表达分析

Genome-wide Identification and Expression Analysis of CIPK Gene Family in Medicago truncatula

CIPK作为Ca^(2+)信号通路中CBL蛋白的直接靶标蛋白广泛存在于植物中,其与植物生长发育及非生物胁迫响应密切相关。通过同源比对,在蒺藜苜蓿全基因组中共筛选得到28条CIPK同源序列,分布于全基因组的7条染色体上,MtCIPKs编码蛋白序列长度介于319~510个氨基酸之间;依据内含子多少,通过进化分析所分成的3个群组可分为无或少内含子组(GroupⅠ)以及多内含子组(GroupⅡ和GroupⅢ);大多MtCIPKs蛋白结构较为保守,其N端均存在1个催化激活结构域(MtCIPK7除外),C端均含有调控域NAF结构域;成员中共鉴定获得15种保守模体,其中N端motif更为保守;基因家族成员中有6对基因在进化过程中存在共线性关系,进化分析发现其经历了纯化选择,且分离时间估算预示其来自蒺藜苜蓿第一次全基因组复制甚至更早的基因组复制事件;经蛋白互作分析预测,共获得6对MtCBL-MtCIPK互作蛋白;基因家族成员上游启动子区域存在多种参与响应植物激素和非生物胁迫的顺式作用元件,且类型和数量在各成员间存在一定差异;基因芯片表达数据分析显示,部分家族成员呈现一定组织表达特异性,在响应干旱或高盐胁迫的过程中其表达模式也存在明显差异,MtCIPK9、MtCIPK10、MtCIPK23和MtCIPK24是参与干旱和(或)高盐胁迫响应的重要功能候选基因。

CIPK,as the direct target protein of CBL protein in the Ca^(2+)signaling pathway,is widely present in plants,and is closely related to plant growth and development and abiotic stress response.In this study,a total of 28 CIPK homologous sequences were screened from the whole genome of Medicago truncatula through homology comparison,which were distributed on 7 chromosomes of the whole genome.The length of MtCIPK coding protein sequence was between 319~510 amino acids;According to the number of introns,the gene members of the three groups divided by evolutionary analysis can be divided into no or few intron groups(GroupⅠ)and multi-intron groups(GroupsⅡandⅢ).Most of MtCIPK had a conservative proteins structure.There was a catalytic activate domain at the N-terminus(except MtCIPK7),and a regulatory NAF domain at the C-terminus.A total of 15 conserved motifs were identified,of which N-terminal motif was more conserved.There were six pairs of MtCIPK genes that had a collinearity in the process of evolution.Evolutionary analysis showed that they had undergone purification selection,and the estimation of separation time indicated that they come from the first whole genome replication or even earlier genome replication events of M.truncatula.Total six pairs of MtCBL-MtCIPK interaction proteins were predicted by protein interaction analysis.There were many cis-acting elements involved in the upstream promoter region of gene family members involved in response to plant hormones and abiotic stress,and the types and quantities were different among members.Microarray expression data analysis indicated that some family members showed certain tissue expression specificity,and their expression patterns were also significantly different in response to drought or high-salt stress.Finally,MtCIPK9,MtCIPK10,MtCIPK23 and MtCIPK24 were important functional candidate genes involved in drought and/or high-salt stress response.