Search

Cymbopogon is an important aromatic and medicinal grass with several species of ethnopharmaceutical importance. The genus is extremely rich in secondary metabolites, monoterpenes like geraniol and citral being principal constituents, also used as biomarker for classification and identification of Cymbopogon chemotypes. In the light of this, present study involved RNA sequencing and comparison of expression profiles of four contrasting Cymbopogon species namely C. flexuosus var. Chirharit (citral rich and frost resistant), C. martinii var. PRC-1 (geraniol rich), C. pendulus var. Praman (the most stable and citral-rich genotype), and Jamrosa (a hybrid of C. nardus var. confertiflorus × C. jwarancusa (rich in geraniol and geranyl acetate). The transcriptome profiles revealed marked differences in gene expression patterns of 28 differentially expressed genes (DEGs) of terpenoid metabolic pathways between the four Cymbopogon sp. The major DEGs were Carotenoid Cleavage Dioxygenases (CCD), Aspartate aminotransferase (ASP amino), Mevalonate E-4 hydroxy, AKR, GGPS, FDPS, and AAT. In addition, few TFs related to different regulatory pathways were also identified. The gene expression profiles of DEGs were correlated to the EO yield and their monoterpene compositions. Overall, the PRC-1 (C. martinii) shows distinguished gene expression profiles from all other genotypes. Thus, the transcriptome sequence database expanded our understanding of terpenoid metabolism and its molecular regulation in Cymbopogon species. Additionally, this data also serves as an important source of knowledge for enhancing oil yield and quality in Cymbopogon and closely related taxa. KEY MESSAGE: Unfolding the new secretes surrounding EO biosynthesis and regulation in four contrasting Cymbopogon species., Competing Interests: Competing interest The authors declare no competing financial and non-financial interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

• Exploration of the C. martinii inflorescence transcriptome. • C. martini inflorescence contains an abundance of terpenoids, and terpenoid biosynthesis is regulated by multiple genes. • C. martini transcriptome data is a valuable bio-resource for information to manipulate essential oil yield and quality. • Essential oil composition of C. martinii revealed geraniol as the most abundant monoterpene present in the essential oil. • C. martini transcriptome revealed 60 transcription factors using Plant Transcription factor database. Cymbopogon martinii belongs to the family Poaceae and provides an aromatic essential oil of large applications in fragrance, perfumery, cosmetics and pharmaceuticals. The essential oil from this genus has two dominating monoterpenes, geranyl acetate and geraniol. Owing to the tremendous applications of the essential oil from this genus, knowledge of the biochemical and molecular regulatory processes and expressions of genes involved in terpenoid biosynthesis pathway, is highly desirable to improve the quality and yield of essential oil. We performed high-throughput transcriptome sequencing of C. martinii for identification of the genes related to terpenoids biosynthesis using Illumina HiSeq-2000 platform. In the present study, approximately 286,309,78 reads of high quality were generated. De novo assembly yielded 96,470 unigenes (≥200 bp) and 84,168 (≥500 bp). Functional annotation of total 96,470 (56%) unigenes was done. More than 4500 enriched unigenes were assigned to 367 KEGG pathways among various categories, i.e. protein processing, cellular processes, metabolism, steroid biosynthesis, and others. 913 unigenes in the metabolism category were assigned to 287 metabolic pathways linked with secondary metabolism. To explore the putative functions of six genes encoding alcohol dehydrogenase, geranyldiphosphate synthase, fernasyldiphosphate synthase, aldehyde dehydrogenase, aldo-keto reductase and alcohol acyltransferase expression patterns were studies using qRT-PCR. We have also identified 60 transcription factors in C. martini transcriptome using Plant Transcription factor database. To the best of our knowledge, this is the first-ever report on the C. martinii inflorescence transcriptome which will facilitate the understanding of the molecular mechanisms of essential oil biosynthesis in the genus Cymbopogon and related plant families. [ABSTRACT FROM AUTHOR]