福州双瓣茉莉萜烯类合成酶基因家族鉴定及其响应茉莉酸甲酯的表达分析

Terpene synthase gene family in Jasminum sambac var. Fuzhou bifoliatum: genome-wide analysis and expression pattern in response to methyl jasmonate

摘要:

萜烯类合成酶(terpene synthases,TPSs)是合成花香中多种萜类化合物的关键酶，但TPS基因在福州双瓣茉莉(Jasminum sambac var.Fuzhou bifoliatum)中全基因组鉴定和响应茉莉酸甲酯(methyl jasmonate,MeJA)的表达模式分析少见报道。本研究利用生物信息学的方法对双瓣茉莉TPS (DJTPS)基因进行全基因组鉴定，对基因家族成员的理化性质、亚细胞定位、蛋白互作、系统进化、亚家族分类、染色体定位及共线性、基因结构、顺式作用元件和保守基序进行分析，并利用转录组数据和实时荧光定量PCR (quantitative real-time PCR,qRT-PCR)分析DJTPS家族在不同组织器官下及在MeJA处理下的表达模式。结果表明，在双瓣茉莉全基因组中一共鉴定到32个DJTPS家族成员，不均匀地分布在9条染色体上，所编码蛋白质均为亲水性蛋白，大多数定位于细胞质；系统进化分析显示，DJTPS家族分为TPS-a、TPS-b、TPS-c、TPS-e/f和TPS-g共5个亚家族；共线性结果揭示了双瓣茉莉中共有10组复制事件，大部分都经历了纯化选择；分析双瓣茉莉与其他6个物种之间的TPS同源基因对，发现了不同数量的同源基因对；基因结构和保守基序分析结果显示，同一亚家族的外显子数量和基序数目具有一定的保守性；对顺式作用元件分析发现，DJTPS家族中存在多个可能涉及MeJA响应的元件；转录组和qRT-PCR数据分析显示，多个TPS基因在不同组织器官中特异性表达，在花中特异性表达的基因最多；14个TPS基因在MeJA处理5 h或6 h后表达上调，其中DJTPS03、DJTPS04和DJTPS21在MeJA处理后表达量显著增加。本研究初步证明了MeJA能够促进DJTPS家族成员在开花关键时期的表达，从而促进萜类化合物的合成，提高花香的品质。

Abstract:

Terpene synthases (TPSs) play a crucial role in the synthesis of terpenoids that contribute to the scent profiles of flowers. However, few studies report the genome-wide analysis of TPSs gene in Jasminum sambac var. Fuzhou bifoliatum and their expression pattern in response to methyl jasmonate (MeJA). In this study, we employed bioinformatics tools for genome-wide analysis of the J. sambac TPS (DJTPS) gene family and determined the physical and chemical properties, subcellular location, protein-protein interactions, phylogenetic relationship, subfamily classification, chromosomal location and collinearity, gene structure, conserved motifs, and promoter cis-acting elements. The expression patterns of DJTPSs in different tissues and in response to MeJA treatment were analyzed based on the transcriptome data combined with quantitative real-time PCR (qRT-PCR). We identified 32 intact DJTPS genes in the genome of J. sambac, which presented uneven distribution across nine chromosomes. All the deduced proteins were hydrophilic, predominantly localized in the cytoplasm. The phylogenetic analysis classified the DJTPS genes into five subfamilies: TPS-a, TPS-b, TPS-c, TPS-e/f, and TPS-g. The results of the collinearity analysis showed a total of 10 sets of replication events in DJTPSs, most of which underwent purifying selection. A comparative analysis of TPS homologous gene pairs was performed among J. sambac var. Fuzhou bifoliatum and other six species, which revealed different number of homologous gene pairs. The number of exons and motifs was conserved within the same subfamily. DJTPS genes carried multiple elements that may be involved in the response to MeJA. In addition, the transcriptome and qRT-PCR data unveiled that several TPS genes exhibited tissue-specific expression patterns, and the genes with specific expression in flowers were the most. Upon exposure to MeJA, 14 TPS genes showcased upregulated expression 5 h or 6 h post-treatment, and DJTPS03, DJTPS04 and DJTPS21 showed significantly increased expression levels after MeJA treatment. This study provides preliminary evidence that MeJA possesses the ability to enhance the expression of DJTPS genes during the critical flowering stage, which will facilitate the synthesis of terpenoids and improve the quality of floral fragrance.