Over expression of IPP isomerase and limonene synthase enzymes in Mentha spicata and their influence on the terpenoid metabolism

Abstract

This study explores the role of terpenoid biosynthesis genes in Mentha spicata (MS); IPP isomerase (Iso) and limonene synthase (Limo) in Mentha spicata. Transgenic M. spicata plants required for the study were obtained by cloning cDNAs of IPP isomerase and Limonene synthase from hybrid poplar and Citrus respectively into the expression vector pB1121. The resulting vectors p1121 pIso and pLimo were introduced into M. spicata via Agrobacterium tumefaciens. Consequently the secondary metabolites produced in transgenic M. spicata were profiled with GC-MS analysis and SDE methods. A greater number of terpenoids were found in transgenic M. spicata than the wild type plant. The extracts from transgenic MSIso plants showed the presence of 1,8-cineole, linalool, camphor, terpinene, lomonene, borneol, safranal, geraniol, thymol, 1-alpha-terpineol and methyl eugenol, while transgenic MSLimo extracts contained linalool, menthone, terpinene, limonene, menthol-isomer, thymol, and piperitone. The 2DE protein profile of transgenic M. spicata revealed 16 and 22 differentially expressed proteins in MSIso and MSLimo transgenic plants respectively. The differentially expressed proteins are currently being identified and are anticipated to be involved modifying the terpenoid metabolism.