Transcriptome Analysis of JA Signal Transduction, Transcription Factors, and Monoterpene Biosynthesis Pathway in Response to Methyl Jasmonate Elicitation in Mentha canadensis L.

Xiwu Qi,Hongfei Lu,Weilin Li,Li Li,Chengyuan Liang,Zequn Chen,Dongbei Xu,Yin Chen,Xu Yu,Hailing Fang

doi:10.3390/ijms19082364

Abstract

Mentha canadensis L. has important economic value for its abundance in essential oils. Menthol is the main component of M. canadensis essential oils, which is certainly the best-known monoterpene for its simple structure and wide applications. However, the regulation of menthol biosynthesis remains elusive in M. canadensis. In this study, transcriptome sequencing of M. canadensis with MeJA treatment was applied to illustrate the transcriptional regulation of plant secondary metabolites, especially menthol biosynthesis. Six sequencing libraries were constructed including three replicates for both control check (CK) and methyl jasmonate (MeJA) treatment and at least 8 Gb clean bases was produced for each library. After assembly, a total of 81,843 unigenes were obtained with an average length of 724 bp. Functional annotation indicated that 64.55% of unigenes could be annotated in at least one database. Additionally, 4430 differentially expressed genes (DEGs) with 2383 up-regulated and 2047 down-regulated transcripts were identified under MeJA treatment. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment indicated that “Monoterpenoid biosynthesis” was one of the most significantly enriched pathways in metabolism. Subsequently, DEGs involved in JA signal transduction, transcription factors, and monoterpene biosynthesis were analyzed. 9 orthologous genes involved in menthol biosynthesis were also identified. This is the first report of a transcriptome study of M. canadensis and will facilitate the studies of monoterpene biosynthesis in the genus Mentha.

Highlights

The genus Mentha has important economic value for its abundance in essential oils that are widely used in the flavor, fragrance, and aromatherapy industries [1]
Transcriptome sequencing was performed for M. canadensis under control check (CK) and methyl jasmonate (MeJA) treatment using Illumina HiSeqTM 4000
High-throughput RNA-seq was applied to characterize the transcriptomes of M. canadensis treated with MeJA

Summary

Introduction

The genus Mentha has important economic value for its abundance in essential oils that are widely used in the flavor, fragrance, and aromatherapy industries [1]. The catalytic mechanisms of monoterpene biosynthetic enzymes have been extensively studied in peppermint (Mentha × piperita L.) and spearmint (Mentha spicata L.), two well-known Mentha plants that have been employed as model systems for the study of monoterpene biosynthesis [2,3,4,5,6,7]. In genus Mentha, a variety of monoterpenes including (−)-menthol, (+)-neomenthol, (+)-isomenthol, (+)-carvone, (+)-menthofuran, and so on, are synthesized and stored in the peltate glandular trichomes on the aerial surfaces of the plant [8,9]. The oil compositions vary in different Mentha species and are regulated by transcriptional abundance, catalytic properties of enzyme catalysts, and cell type-specific epigenetic processes [9]

Methods

Results

Discussion

Conclusion