Induced defense in plants: A short overview

Abstract

Phytopathogens adopt different strategies to infect and colonize the plant tissues and in turn, plants also have evolved diverse mechanisms to recognize specific signatures of the pathogens to identify the dangerous non-self ones. Pathogen recognition activates an array of defense mechanisms collectively known as induced resistance that includes the hypersensitive response (HR), in which a few plant cells at the site of infection die, limiting the spread of disease. In addition to the locally effective HR, pathogen recognition also triggers various inducible systemic defenses in plant parts distant from the site of primary infection, leading to an enhanced capacity to defend against subsequent infection. The molecular mechanism of induced plant defense is exceedingly complex and involves extensive reprogramming that bring physical, biochemical and transcriptional changes. The responses include cell wall thickening, callose deposition, production of reactive oxygen species and release of signalling compounds such as salicylic acid, jasmonic acid, ethylene and abscisic acid that perturb the infection. This review is a brief overview of the induced defense mechanisms in plants, with special reference to phytopathogenic bacteria-plant interactions. © 2013 The National Academy of Sciences, India.