Chapter 4 - Differential Responses of Plants to Biotic Stress and the Role of Metabolites

Abstract

Plants contribute a lot to this universe but they have to face many stresses of biotic or abiotic nature. Biotic stress is a severe environmental constraint to the plant’s productivity. Biotic stress induces loss in crop yield probably more than the cumulative losses from all other factors. In any stress, the type and duration are critical for plant growth. This chapter covers the impact of adverse effects of biotic stress on the growth and productivity of plants. It also describes the mechanism of biotic stress resistance in plants on the basis of their morphological, physiological, and molecular aspects. Plants use various defensive strategies to tolerate these adverse factors. Of the various defensive mechanisms, one is the production of reactive oxygen species. These defensive mechanisms against biotic stress are generated as a result of the continuous interaction between plant and pathogen. Plants’ responses to biotic stress are not only the alteration in anatomical features, such as formation of a waxy cuticle, trichrome, setae, and spines, but also the production of various secondary metabolites. Such types of plant responses have been observed against bacteria, fungi, and pests. These secondary metabolites trigger different plant defense mechanisms in the form of ascorbic acid, antioxidative enzymes (peroxidase, polyphenol oxidase, lipoxygenases), salicylic acid, jasmonic acid, and Ca2+ against biotic stress and also act as toxins (terpenes, alkaloids, and phenolic compounds) against plant pathogens.