谷子SBP蛋白基因家族的鉴定及表达分析

Genome Wide Identification and Expression Analysis of the SBP Gene Family in Foxtail Millet

为了深入分析SBP基因家族在谷子中的功能作用,本研究在谷子全基因组水平,通过NCBI blast及HMMER search等生物信息学方法进行了谷子SBP基因家族鉴定,分析了SBP蛋白理化性质及系统发育,利用RT-qPCR分析了谷子SBP基因在PEG和ABA胁迫下的表达情况。结果表明,谷子SBP基因家族有19个成员,位于9条染色体上,编码的氨基酸序列长度为199~1 118 aa。谷子SBP蛋白系统发育树结果显示,该蛋白家族可分为两大类:第一类分为六个亚类,第二类仅有一个SBP蛋白。谷子SBP蛋白家族成员的外显子数从2~11个不等,且均为亲水性蛋白。亚细胞定位预测结果显示,除SBP7外,所有的SBP蛋白在细胞核中均有信号。谷子SBP蛋白与拟南芥SBP蛋白在进化关系上较远,而与高粱、水稻SBP蛋白进化关系较近。谷子SBP基因家族启动子区域的顺式作用元件主要为植物激素、干旱、光照及病原菌、创伤类的响应元件。RT-qPCR分析结果显示,PEG和ABA胁迫诱导下,SBP基因在叶和茎中的表达均上调,表达量增幅表现为:叶>茎。PEG胁迫后SBP基因的表达增长量显著高于外源ABA诱导;其中,SiSBP13的表达量增幅最大,PEG胁迫4 h叶和茎中的表达量分别达到未胁迫时的180倍和15倍,ABA诱导4 h茎中的表达量最高达到未胁迫时的8倍,而叶中的表达量持续升高,24 h时达到未胁迫时的28倍。本研究为下一步深入研究SiSBPs基因在谷子生长发育阶段中的功能奠定了基础,也为谷子功能基因的挖掘利用提供了候选基因。

In order to further elucidate the important function of SBP gene family in foxtail millet, NCBI blast and HMMER search were used to identify the SBP genes in foxtail genome, and to analyze the physicochemical properties and phylogenetic tree of SBP family in foxtail millet. The expression SBP gene family in foxtail millet treated with PEG and ABA were detected by real-time fluorescence quantitative PCR(RT-qPCR). The results showed that 19 members of SBP gene family were identified from the whole genome of foxtail millet and they encoded proteins with 199-1 118 aa, which distributed across 9 chromosomes. The results of phylogenetic tree showed that the SBP protein could be divided into 2 categories. The first category was classified into 6 sub-categories, and the second category only contained one SBP proteins. The numbers of exons were variable, ranged from 2-11, and all of the SBP proteins were hydrophilic protein. The results of subcellular localization prediction showed that the members of the gene family were located mainly in the nucleus except SBP7. Cluster analysis showed that foxtail millet SBP was closely related to monocotyledonous sorghum and rice than to cotyledonous Arabidopsis thaliana. Upstream promoter region analysis founded a large number of cis-acting elements closely related to hormones, drough, light, pathogenic factors and stress condition. The results of RT-qPCR showed that the relative expression of SBP gene was up-regulated under PEG and ABA treatment, and the expression quantity of SBP in leaf was higher than that in stem. The expression quantity of SBP under PEG was significantly higher than ABA treatment. The expression levels of SiSBP13 in leaves and stems after 4 hours of PEG stress were 180 and 15 times as that before treatment. After 4 hours of ABA induction, the expression of SiSBP13 in stems was up to 8 times that before stress. After 24 hours of induction, the expression of SiSBP13 in leaves was 28 times higher than that before stress. This study laid an important foundation for further analysis of the specific functions of SBP genes at different development stages in foxtail millet.