几种芸薹属作物APX家族基因的鉴定与序列分析

抗坏血酸过氧化物酶(APX)是植物体叶绿体清除H₂O₂的关键酶。为了探究芸薹属作物中APX家族基因的序列特点和表达模式,本研究利用生物信息学方法,从大白菜、甘蓝和欧洲油菜中分别鉴定出10、9和22条APX 家族基因,对这41个成员序列特点、染色体分布、CDS保守域、蛋白保守结构域、蛋白三级结构和系统进化关系等进行预测分析,并通过基因表达数据库分析这些基因在高温、干旱和生物胁迫等逆境条件下的表达模式。结果表明,APX在进化树上可分为8个亚族,分散在不同的染色体上;这些APX基因拥有相对稳定的CDS保守结构域、蛋白保守结构域和三级结构,都具有过氧化物酶功能域,在peroxidase功能域的后端均含有一个螺旋结构状的保守域Motif6。APX基因的Ka/Ks值均小于1,表明APX家族基因整体上正在经历纯化选择。大部分APX1和APX2基因在受到高温胁迫时表达上调,其中BrAPX2a在大白菜的胚和胚乳中强烈响应高温胁迫,但在大白菜其他部位表达微弱,存在一定的表达组织特异性。APX3、APX4等基因对干旱和高温胁迫响应不明显;甘蓝3个APX1基因在白粉虱为害胁迫时表达上调。本研究结果为芸薹属作物APX家族成员的克隆、表达与功能研究提供了一定参考。

Identification and Bioinformatics Analysis of APX Gene Families in Brassica Plants

Ascorbate peroxidase (APX) is a key enzyme for scavenging hydrogen peroxide in plants, especially in chloroplasts. In order to explore the characteristics and expression patterns of APX family genes in Brassica crops, 10, 9 and 22 APX family genes were identified from B. rapa, B. oleracea and B. napus by bioinformatics in this study. The sequence characteristics, chromosome distribution, CDS motif, protein motif, protein tertiary structure and phylogenetic relationships of 41 APX family genes were predicted and analyzed, and the expression patterns of these genes under high temperature, drought and biotic stress were analyzed by gene expression database. The results showed that APX can be divided into eight subfamilies in the phylogenetic tree and dispersed on different chromosomes. These APX genes possess relatively stable CDS conserved domains, protein conserved domains and tertiary structures, all of which have peroxidase domains. At the back end of the peroxidase domain, there is a conserved domain Motif6 with a helical structure. The Ka/Ks values of the APX gene were much less than 1, indicating that the APX family genes are undergoing purification selection as a whole. Most of the APX1 and APX2 genes were up-regulated under heat stress. Among them, BrAPX2a was strongly responded to heat stress in the embryo and endosperm of Chinese cabbage, but it was weakly expressed in other parts of Chinese cabbage, and it had certain tissue specificity. The genes such as APX3 and APX4 had no obvious response to drought and heat stress; the three APX1 genes in cabbage were up-regulated in the stress of whitefly. The results of this study provide a reference for cloning, expression and function of APX family members of Brassica crops.