ABSTRACT
Introduction Control of plant diseases has become a formidable task for the farmers in their efforts to produce crops with high yield and quality. Farmers worldwide have relied upon chemical control for the management of plant diseases. However, the heavy use of chemical pesticides often leads to deterioration of the agroecosystems, in addition to its being hazardous to the health of humans and animals. Present ecological concerns about frequent fungicide applications are serious and include worker safety, contamination of drainage water and consumer exposure to fungicide residues. However, the use of fungicides, earlier used to protect the crop from diseases, has also been drastically reduced to protect the environment. Therefore, alternative control measures are needed to fulfill grower’s efforts to achieve pesticide-free production. During the last ten years, a great effort has been done in several countries to develop alternative and safe control methods to plant diseases. Alternatively, induced resistance of plant pathogens has increased and indeed offers many attractions as an alternative strategy. Plants can be induced locally and systemically to become more resistant to diseases through various biotic or abiotic stresses. The biological inducers include necrotizing pathogens, non-pathogens, root colonizing bacteria or arbuscular mycorrhizal fungi. Resistance-inducing chemicals that are able to induce broad resistance to disease offer an additional option for the farmer to complement genetic disease resistance and the use of
fungicides. Therefore, in this review, authors discuss further information about induced resistance to plant diseases, to understand how plants integrate pathogen-induced signals into specific defense responses with focusing on the most important key components including salicylic acid (SA), jasmonic acid (JA) and ethylene (ET); explaining the biochemical changes associated with induced resistance; understanding the role of bacteria in the rhizosphere and arbuscular mycorrhiza fungi as bio-inducers mediated for induced resistance against pathogens; and the ability and strength of exogenous application of chemical inducers such as SA, K2HPO4 and their role for inducing resistance.
