芝麻赤霉素合成相关基因鉴定与表达分析

Identification and expression analysis of GA related genes in sesame

赤霉素的生物合成是多种酶促反应的过程,与植株发育、逆境响应密切相关。为分析芝麻基因组中赤霉素合成相关基因的分布、结构和活性特征,本研究以芝麻基因组序列和不同组织转录组为对象,通过生物信息学方法,从中共鉴定出32个赤霉素合成相关基因,分属7个不同的基因家族,分布在除5号染色体外芝麻所有的染色体上。不同基因家族蛋白质肽链长度存在较大差异,其中CPS家族的蛋白质序列最长,平均包含776个氨基酸残基;KAO家族蛋白序列长度的变异最大,在401~834个氨基酸之间。所有芝麻赤霉素合成相关基因编码的蛋白质预测为亲水性蛋白。与拟南芥、水稻、大豆、葡萄、高粱、番茄等物种相比,芝麻中赤霉素合成相关基因数目处于中等水平,但CPS家族中芝麻的基因数目明显多于其他物种,进化分析表明,在分析的7个物种中,芝麻与番茄具有较近的进化关系。在不同组织中,7个相关基因家族表达模式不同。KS家族基因在种子、茎尖和叶片中表达相对较高;CPS家族基因在心皮和种子中活性较强,但在茎尖和叶片中几乎没有表达;KAO和KO家族基因在不同组织中整体上具有相对较高的活性,而KS、GA3ox家族的基因在不同组织中整体表达量较低。就不同组织而言,种子中的GA合成相关基因活性整体较高;而在根尖、茎尖、叶片等与芝麻植株形态建成密切相关的3个组织中,这些基因表达以根尖较突出、其次为茎尖,在叶片中的活性整体较低。本研究为解析芝麻赤霉素合成相关基因的结构特征及其在不同组织中的作用特点提供了基因信息和理论参考。

The biosynthesis of gibberellin(GA) is a process of various enzymatic reactions and is closely related to plant development and stress response.To explore the distribution,structure and activity of sesame GA related genes,sesame genome sequence and transcriptomes from different tissues were studied based on bioinformatics methods.It showed that sesame had 32 GA related genes belonging to 7 different gene families,and these genes were distributed on all chromosomes except the chromosome 5.The protein sequence lengths of the different gene families were quite different.The CPS genes had the longest protein and contained 776 amino acid residues on average.The KAO proteins exhibited a great variation in size,varying from 401 to 834 amino acids.All the proteins encoded by GA related genes were predicted to be hydrophilic proteins.Compared with other species inclusing Arabidopsis,rice,soybean,grape,sorghum and tomato,the total number of GA related genes in sesame is not outstanding,but more CPS genes were observed in sesame.Evolution analysis indicated that sesame and tomato had a closer evolution relationship among the 7 species.In various sesame tissues,the 7 GA related gene families displayed quite different expression patterns.KS genes were highly expressed in seeds,stem tips and leaves.CPS genes were more active in pericarps and seeds,but were hardly expressed in stem tips and leaves.KAO and KO genes were constitutively and higly expressed in all tissues,while KS and GA3 ox genes showed low levels of expression.Among the different tissues,the GA related genes generally showed higher activity in seed,then in root tip and in stem tip.This study provided important genetic information and theoretical references to analyze the characteristics of GA related genes in sesame and its role in different tissues.