Induced Resistance: A Novel Biorational Approach for Plant Protection*

Pests are the most important biotic constraints in crop production worldwide. Developing ecologically sound biorational plant protection strategies is important for achieving food security particularly in developing nations. Most plant protection methods currently in vogue rely on two approaches: (i) use of external factors such as hazardous chemical pesticides or relatively safer products like botanicals and biocontrol agents, or (ii) use of plant's internal factors such as resistant genes incorporated either through conventional breeding or genetic engineering. In contrast to these, induced resistance is a novel non-conventional approach that uses external factors to enhance the plant's internal defense machinery to combat the pathogens and pests. Induced resistance that exploits the plant's latent defense capabilities could be proposed as an ecologically sound biorational alternative to the use of hazardous chemical pesticides. Basic characteristics of two major types of induced resistance (Systemic acquired resistance (SAR) and induced systemic resistance (ISR)), mechanisms of induction, various types of inducers, field efficacy of ISR and SAR, advantages and ecological considerations in implementing induced resistance for plant protection are briefly discussed in the light of recent advances in research on induced resistance.