Abscisic acid in the plants-pathogen interaction

Information available concerning the role of ABA in the interaction between plants and pathogenic microorganisms allows a conclusion that this phytohormone is required for plant defense. For the development of plant resistance, short-term increases in the ABA level are of importance during the early stages of plant interaction with pathogens, which trigger anti-stress programs in plants, primarily related to the synthesis of callose. At the same time, high ABA concentrations maintained for a long time reduce efficiency of defense systems controlled by salicylic and jasmonic acids and ethylene. ABA was shown to suppress expression of some genes of defense proteins, including those involved in the synthesis and metabolism of phenolic compounds and lignin. ABA is evidently involved in plant defense mechanisms against pathogens as a regulatory element.