Plant secondary metabolites in defense against phytopathogens: Mechanisms, biosynthesis, and applications

Abstract

Plants have evolved elegant defense strategies against biotic and abiotic stresses by principally using the secondary metabolites alkaloids, terpenoids, flavonoids; phenolics, etc. Secondary metabolites (e.g. alkaloids, terpenoids, flavonoids, and phenolics) play roles in constitutive defenses (e.g., tomatine) and induced responses (e.g., phytoalexins), that enable plants effective defense against pathogens and herbivores. This review integrates current information on biosynthesis and ecological roles of secondary metabolites ranging from biotrophic, and hemi-biotrophic to necrotrophic pathogens in the activation of such a metabolic diversity. This present discussion is about the regulation of response via their key signaling molecules, namely jasmonic acid and salicylic acid, and their function from both sides of defense trade-offs. Overview of recent advances in genetic engineering and metabolic engineering approaches for engineering the production of metabolites to replace synthetic agrochemicals sustainably. This review emphasizes the role of secondary metabolites in integrated pest management and sustainable agriculture, despite their potential pharmaceutical applications. In the future, research should address the molecular base of secondary metabolism and open ways for biotechnological tools to develop climate-resilient crops. This review integrates basic concepts of plant defense with an applied biotechnology theme to provide lessons learned on the use of secondary metabolites to promote sustainable agriculture.