Differential expression of farnesyl diphosphate synthase gene from Withania somnifera in different chemotypes and in response to elicitors

摘要

Withania somnifera (L.) Dunal (Family, Solanaceae), commonly known as Ashwagandha is one of the most valuable medicinal plants synthesizing large number of pharmacologically active secondary metabolites known as withanolides. Though the plant has been well characterized in terms of phytochemical profiles as well as pharmaceutical activities, not much is known about the genes responsible for biosynthesis of these compounds. In this study, we have characterized a gene encoding farnesyl diphosphate synthase (FPPS; EC 2.5.1.10), a key enzyme in the pathway of biosynthesis of isoprenoids, from W. somnifera. The full-length cDNA of Withania somnifera FPPS (WsFPPS) of 1,253 bps encodes a polypeptide of 343 amino acids. The amino acid sequence homology and phylogenetic analysis suggest that WsFPPS has close similarity to its counterparts from tomato (SlFPPS) and capsicum (CaaFPPS). Using semi quantitative RT-PCR, the expression pattern of the WsFPPS gene was analyzed in different tissues of Withania chemotypes (NMITLI-101, NMITLI-108, NMITLI-118 and NMITLI-135) as well as in response to elicitors (salicylic acid and methyl jasmonate) and mechanical wounding. The expression analysis suggests that WsFPPS expression varies in different tissues (with maximal expression in flower and young leaf) and chemotypes (with highest level in NMITLI-101) and was significantly elevated in response to salicylic acid, methyl jasmonate and mechanical injury. This is the first report on characterization of an isoprenoid pathway gene involved in withanolide biosynthesis.