Partial sequence isolation of DXS and AOS genes and gene expression analysis of terpenoids and pyrethrin biosynthetic pathway of Chrysanthemum cinerariaefolium under abiotic elicitation

Abstract

One of the most important issues in crop production is the use of agrochemicals. The use of synthetic or manufactured chemicals on crops has made a frightening image of health problems. A concern about chemical residues on food products has led to seek for new alternative compounds with fewer side effects on humans and environment. Pyrethrum (Chrysanthemum cinerariaefolium) belongs to the Asteraceae family is one of the most important resources of natural insecticides which produce pyrethrin I. Pyrethrin I has an acidic moiety and an alcohol moiety, the acidic moiety of these molecules is a monoterpene with a cyclopropane ring and biosynthesized via 2-C-methylerythrol 4-phosphate pathway (MEP) and alcohol moiety is biosynthesized via the lipoxygenase pathway through membrane lipids. At the end, the acidic moiety and alcohol moiety from separate pathways conjugate together by TcGLIP enzyme, a kind of GLIP lipase family. Based on the importance of pyrethrin I as a natural insecticide in pyrethrum partial sequences of 1-deoxy d-xylulose 5-phosphate synthase (DXS) gene from the MEP pathway and Allene oxide synthase (AOS) gene from the lipoxygenase pathway were isolated by specific primers to study their expression patterns in different conditions. Along with this, gene expression patterns of DXS, chrysanthemyl diphosphate synthase, farnesyl diphosphate synthase, GLIP lipase (TcGLIP), AOS and 13-lipoxygenase were investigated under abiotic elicitors including trans-cinnamic acid, methyl jasmonate, salicylic acid and ultra-violet ray by RT-PCR to determine the effect of aforementioned elicitors on transcript levels. Results showed that the expression of genes in the biosynthetic pathway of pyrethrin I under methyl-jasmonate, salicylic acid and ultra-violet ray treatments were up-regulated in compared with control plants.