Molecular Basis of Plant-PGPM Interactions During Amelioration of Biotic Stress

Plant growth-promoting microorganisms (PGPMs) play a substantial role in coping with the biotic stresses. A variety of PGPMs including Bacillus sp., Pseudomonas sp. and Trichoderma sp. have shown their capability to combat the bacterial, fungal and viral infections in plants by changing the physical attributes, production of volatile compounds and interfering with the plant defence systems. The plant-microbe is known to interact with two major types of systemic resistance including systemic acquired resistance (SAR) and induced systemic resistance (ISR) after pathogen attack. The induction of SAR and ISR by PGPMs brings a significant change in expression of defence-related genes, chitinase and cell wall-degrading enzyme production and synthesis of antimicrobial secondary metabolites. Accumulation of antimicrobial pathogen-related (PR) proteins induced by PGPMs provides disease resistance to the plants. Production of reactive oxygen species (ROS) and hypersensitive (HR) responses in plants are also some of the molecular changes induced by PGPMs to combat the pathogen attack. Recent developments in proteomics, metabolomics and transcriptomics studies of plants during interactions of plantpathogen- PGPMs with the help of advanced sequencing and mass spectrometry technologies have further improved the in-depth knowledge of molecular changes associated with the interaction. A detailed study of molecular changes induced by plant growth-promoting endophytes and non-culturable PGPMs is also required to decipher such complex interactions. Studying changing pathobiome and role of climate change at molecular level in such interactions can be helpful to combat the emergence of disease-resistant pathogens and in the development of diseaseresistant plant varieties.