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

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.