基于转录组测序的牛蒡木质素类物质生物合成途径及关键酶基因分析

Transcriptome analysis reveals key enzyme genes involved in lignin biosynthesis pathway in Arctium lappa

目的获得牛蒡Arctiumlappa根功能基因数据库,分析其木质素类化合物生物合成途径及关键酶基因。方法以牛蒡根为研究对象,利用华大基因BGISEQ-500测序平台进行转录组测序,通过从头组装获得Unigene,利用各种已有的核酸和蛋白质数据库对Unigene进行注释和分类,利用KEGG代谢途径分析木质素生物合成途径及其关键酶基因,利用三维同源建模分析苯丙氨酸解氨酶(AlPAL)的结构特点。结果通过转录组测序共获得54 215个Unigene,其中42 003个Unigene被任一数据库注释,1 668个Unigene被注释到54个转录因子家族中;KEGG途径分析鉴定了423个Unigene参与了木质素的生物合成。AlPAL空间结构模型显示其为同型四聚体,每个单体由3个结构域组成,包括4-甲基-咪唑-5-酮(MIO)结构域、核心结构域和屏蔽结构域,其中MIO结构域包含保守的三肽ASG,构成AlPAL酶的催化活性中心。结论对牛蒡根转录组进行分析,为牛蒡功能基因鉴定、次生代谢途径解析及其调控机制研究奠定了实验基础。

Objective To obtain the functional genes in Arctium lappa and analyze the key enzyme genes involved in biosynthesis pathway of lignin. Methods The transcriptome dataset of roots of A. lappa was obtained by using the BGISEQ-500 sequencing platform. Unigenes were de novo assembled and annotated according to the existing nucleic acids and protein databases. The key enzyme genes involved in lignin biosynthesis pathway were analyzed and the three-dimensional model of phenylalanine ammonialyase(Al PAL) was generated by the SWISS-MODEL and PyMol. Results A total of 54 215 Unigenes were obtained by de novo assembly, and 42 003 Unigenes were annotated in at least one public database. A total of 1 668 Unigenes were identified to be plant transcription factors(TFs), which belong to 54 TF families, and 423 Unigenes were found to be involved in the biosynthesis pathway of lignin. Structure model indicated that AlPAL was a homotypic tetramer, and each monomer was consisted of three domains, including 4-methyl-imidazole-5-ketone(MIO) domain, core domain and shield domain. The MIO domain contained three conserved amino acids(ASG), which formed the catalytic activity center of the enzyme. Conclusion This study was the first de novo transcriptome assembly of A. lappa, which will lay the foundation for the identification of functional genes, secondary metabolic pathway and the study of regulation mechanism of biosynthesis pathway of lignin in A. lappa in the future.