甜菜BvHAK基因家族全基因组鉴定及其在盐处理下的表达分析

Genome-wide identification of BvHAK gene family in sugar beet (Beta vulgaris) and their expression analysis under salt treatments

摘要:

高亲和性K⁺转运蛋白（high-affinity K⁺ transporter，HAK）是植物中最重要的K⁺转运蛋白家族之一，在植物K⁺吸收和转运过程中发挥重要功能。为探究甜菜BvHAK基因家族成员生物学功能及基因表达模式，采用生物信息学手段，预测了蛋白质的理化性质、基因结构、染色体定位、系统进化、保守基序、三维结构、互作网络、启动子顺式作用元件，并通过qRT-PCR分析了盐胁迫下BvHAKs基因在甜菜不同组织中的表达水平。共鉴定出10个甜菜BvHAK基因家族成员，含有8-10个外显子、7-9个内含子；平均氨基酸个数为778.30，平均分子量为88.31 kDa，等电点为5.38-9.41，跨膜区为11-14个。BvHAK4、-5、-7和-13定位在质膜，而其余定位在液泡膜。系统进化分析发现，高等植物HAK可分为5个簇，分别为Ⅰ、Ⅱ、Ⅲ、Ⅳ和Ⅴ簇，其中Ⅱ簇成员可进一步分为Ⅱa、Ⅱb和Ⅱc等3个亚簇；BvHAK家族成员则分布在前4簇，分别含有1、6、1和2个成员。甜菜BvHAK基因家族主要含有胁迫响应元件、激素响应元件和生长发育响应元件。进一步对BvHAK基因在盐处理下甜菜不同组织中的表达模式分析发现，50和100 mmol/L NaCl不同程度地诱导甜菜地上部和根部BvHAK基因家族成员的表达；高盐（150 mmol/L）则下调了其在地上部的表达水平。这些结果表明，BvHAK基因家族在响应盐胁迫过程中起重要作用。

Abstract:

High-affinity K⁺ transporter (HAK) is one of the most important K⁺ transporter families in plants and plays an important role in plant K⁺ uptake and transport. To explore the biological functions and gene expression patterns of the HAK gene family members in sugar beet (Beta vulgaris), physicochemical properties, the gene structure, chromosomal location, phylogenetic evolution, conserved motifs, three-dimensional structure, interaction network, cis-acting elements of promoter of BvHAKs were predicted by bioinformatic analysis, and their expression levels in different tissues of sugar beet under salt stress were analyzed by qRT-PCR. A total of 10 BvHAK genes were identified in the sugar beet genome. They contained 8-10 exons and 7-9 introns. The average number of amino acids was 778.30, the average molecular weight was 88.31 kDa, and the isoelectric point was 5.38-9.41. The BvHAK proteins contained 11-14 transmembrane regions. BvHAK4, -5, -7 and -13 were localized on plasma membrane, while others were localized on tonoplast. Phylogenetic analysis showed that HAK in higher plants can be divided into five clusters, namely cluster Ⅰ, Ⅱ, Ⅲ, Ⅳ, and Ⅴ, among which the members of cluster Ⅱ can be divided into three subclusters, including Ⅱa, Ⅱb, and Ⅱc. The BvHAK gene family members were distributed in cluster Ⅰ-Ⅳ with 1, 6, 1, and 2 members, respectively. The promoter of BvHAK gene family mainly contained stress responsive elements, hormone responsive elements, and growth and development responsive elements. The expression pattern of the BvHAK genes were further analyzed in different tissues of sugar beet upon salt treatment, and found that 50 and 100 mmol/L NaCl significantly induced the expression of the BvHAK genes in both shoots and roots. High salt (150 mmol/L) treatment clearly down-regulated their expression levels in shoots, but not in roots. These results suggested that the BvHAK gene family plays important roles in the response of sugar beet to salt stress.