Spatial modulation and abiotic elicitors responses of the biosynthesis related genes of mono/triterpenes in black cumin (Nigella sativa)

Abstract

Black cumin (Nigella sativa) is a medicinal herb belongs to the Ranunculacea which raised attention due to its pharmaceutical properties. Medical significance of N. sativa mainly attributed to its oxygenated monoterpenes and triterpene saponins which are biosynthesized via the methyl erythritol phosphate (MEP) and MVA (mevalonic acid) pathways, respectively. In order to improve our understanding of monoterpene and triterpene metabolism the partial sequence of a hypothetical monoterpene synthase (MTS) was isolated from N. sativa for the first time and subsequently the relative gene expression of two genes of monoterpene metabolism including geranyl diphosphate synthase (GDS), the isolated monoterpene synthase (MTS) and two genes of triterpene saponins biosynthesis including squalene epoxidase (SQE) and β- amyrin synthase (βAS) were monitored in response to two universal abiotic elicitors including methyl jasmonate (MJ) and salicylic acid (SA), also in different tissues of N. sativa including leaves, stems, roots, capsules and immature seeds. Results of semi quantitative reverse transcription PCR revealed differential regulation of these genes in N. sativa tissues and also in response to abiotic elicitors. Each gene followed a different expression profile and expression level in target tissues. The expression of all studied genes were up-regulated by exogenous application of MJ and SA on N. sativa leaves (at 24h after treatments), except of GDS which its transcript was not induced by SA. The higher expression of these genes in response to abiotic elicitors might reflect an elevation in the corresponding metabolites; hence elicitation is an applicable tool for enhancement of pharmaceutically active mono/triterpenes in N. sativa.