Stress Protectant Secondary Metabolites and their Metabolic Engineering to Enhance Abiotic Stress Tolerance in Plants

Abstract

Plants produce huge numbers of secondary metabolites, which play many essential roles in their adaptation to the changing environment and during abiotic stresses, such as drought, temperature, salinity, etc. Major classes of secondary metabolites, such as isoprenoids, carotenoids, and flavonoids, exhibited potential of abiotic stress tolerance. Synthesis and accumulation of secondary metabolites markedly increased during abiotic stress to cope with harsh abiotic stress conditions, suggesting a tight link between secondary metabolite accumulation and tolerance of plants to abiotic stresses. Therefore, abiotic stress tolerance of plants can be enhanced by manipulating the synthesis and accumulation of secondary metabolites. Metabolic engineering approaches have been very useful to manipulate biosynthesis and accumulation of secondary metabolites such as isoprenoids, carotenoids, and flavonoids and plant hormones, such as abscisic acid. In the past few years, metabolic engineering of secondary metabolic pathways to confer abiotic stress tolerance has been successfully performed in Arabidopsis (Arabidopsis thaliana), tobacco (Nicotiana tabacum), sweet potato (Ipomoea batatas), alfalfa (Medicago sativa L.), S. europaea, and Brassica (Brassica napus). The present chapter highlights roles of abiotic stress-protecting secondary metabolites and discusses progresses and prospects of metabolic engineering of secondary metabolite biosynthesis to enhance abiotic stress tolerance of plants.