Comparative glandular trichome transcriptome‐based gene characterization reveals reasons for differential (−)‐menthol biosynthesis in Mentha species

Abstract

The genes involved in menthol biosynthesis are reported earlier in Mentha × piperita. But the information on these genes is not available in Mentha arvensis. To bridge the gap in knowledge on differential biosynthesis of monoterpenes leading to compositional variation in the essential oil of these species, a comparative transcriptome analysis of the glandular trichome (GT) was carried out. In addition to the mevalonic acid (MVA) and methylerythritol phosphate (MEP) pathway genes, about 210 and 196 different terpene synthases (TPSs) transcripts were identified from annotation in M. arvensis and M. × piperita, respectively, and correlated to several monoterpenes present in the essential oil. Six isoforms of (-)-menthol dehydrogenases (MD), the last enzyme of the menthol biosynthetic pathway, were identified, cloned and characterized from the transcriptome data (three from each species). Varied expression levels and differential enzyme kinetics of these isoforms indicated the nature and composition of the product, as these isoforms generate both (-)-menthol and (+)-neomenthol from (-)-menthone and converts (-)-menthol to (-)-menthone in the reverse reaction, and hence together determine the quantity of (-)-menthol in the essential oil in these two species. Several genes for high value minor monoterpenes could also be identified from the transcriptome data.

Plant Glandular Trichomes: Natural Cell Factories of High Biotechnological Interest

“…mint), the combination of transcriptomics at different stages of trichome development (see below) and of genome-editing or RNA interference technology should be a powerful approach to address the function of candidate genes. Extensive glandular trichome-specific EST resources were generated for a variety of (nonmodel) plant species (Dai et al, 2010;Tissier, 2012b;Soetaert et al, 2013;Chen et al, 2014;Jin et al, 2014;Trikka et al, 2015;Akhtar et al, 2017). Dedicated trichome-related openaccess resources exist that help researchers mine this vast and increasing amount of trichome-related data.…”

Comparative transcriptome analysis of shoot and root tissue of Bacopa monnieri identifies potential genes related to triterpenoid saponin biosynthesis

“…Transcriptome assay using NGS sequencing has been extensively used to identify genes encoding enzymes ramified in distinct steps of biosynthetic pathways in medicinal plants. Some include the description of genes encoding enzyme catalyzed metabolic steps mediated in the biosynthetic pathway of artemisinin in Artemisia annua [13, 14], withanolides in Withania somnifera [15, 16], cannabinoids in Cannabis sativa [17], ginsenosides in Panax ginseng [18], glycyrrhizin in Glycyrrhiza uralensis [19], picrosides in Picrorhiza kurrooa [20], cardiac glycoside in Calotropis procera [21], menthol content in Mentha species [22], medecinal diterpene in Andrographis paniculata [23] and biosynthesis of steroidal saponins in Asparagus racemosus [24]. …”

Transcriptome Assembly and Gene Expression Analysis of Leaf and Rhizome tissues of Dioscorea opposita

“…RNA-Seq is currently a very popular method that is applied in the exploration of plants at transcriptomic levels. The ultimate aim is often to reveal genes that are involved in the biosynthetic pathways in secondary metabolism of many species [18][19][20][21]. Until now, the genomic resources of D. alata [22], D. rotundata [23], and D. dumetorum [24] have been reported.…”