[Systemic resistance induced by biocontrol agents in plants and its biochemical and cytological mechanisms].

Microbial biocontrol agents (BCAs) are generally used for controlling plant diseases via antagonistic mechanisms including competition, antibiosis, parasitism, and cross-protection. Some BCAs can even promote plant growth, and provide induced systemic resistance (ISR), i. e., induce the plants to have resistance against pathogens including phytopathogenic fungi, bacteria and virus, and in some cases, pest insects and nematodes. ISR is characterized by non-specific, wide spectrum and systemic. It is phenotypically similar to the systemic acquired resistance (SAR) induced by the infection of pathogens, and with the same efficiency but without hypersensitive response (HR) and visible symptoms in plant as SAR, which is helpful to open a new way to develop and improve safer and environmentally friendly strategies for plant protection. In this paper, the research advances on ISR mediated by biocontrol fungi and bacteria, elicitors or determinants, and signaling transduction pathways were summarized, with more emphasis on the biochemical and cytological mechanisms of host plant defense reaction induced by free-living and endophytic BCAs. The potential application of ISR in biocontrol of plant diseases was also discussed.