Plant Immunity Inducers: Strategies to Identify and Isolate Them to Boost Defense Responses in Plants

Plants are constantly challenged by pathogens and pests during their growth period. Application of chemical pesticides to control pests and pathogens has been the most common method of controlling them worldwide. Long-term use of the chemical pesticides not only affects human and cattle health but also produces potential hazardous effects on the environment. Furthermore, due to improper usage of pesticides, the pathogens are evolving resistance to these pesticides. Taking into consideration the health concerns of the stakeholders, food safety, and environmental protection from chemical pesticides, it necessitates devising environmentally effective and cost-efficient strategies to control pathogens by means of boosting plant’s own immunity. Understanding the principles of plant immunity, plant–microbe interactions, and the molecular mechanism/s underlying constitutive and systemic resistance induced by microbial or synthetic elicitors in plants would enable successful detection and isolation of plant immunity inducers. Priming plants with defense inducers will not only provide suitable, cost-effective control measures to control pathogens but also aid in facilitating an integrated pest management system in crop plants. Moreover, combination of chemical and biological agents could provide a wide spectrum of systemic resistance and defense responses against various pests and diseases for sustainable agriculture and crop protection. This chapter highlights the various aspects of plant innate immunity, constitutive and inducible defenses, compatible and incompatible interactions, host responses, and defense signaling leading to plant immunity inducers detection, their mechanism of action and strategies to be devised for their effective utilization to enhance protection against various pests and pathogens in crop plants.