Chitinases produced by microorganisms

Chitinases produced by microorganisms have significant antagonistic effects on plant pathogenic fungi. The possible mechanisms are as follows:

—Disrupting the cell wall structure of pathogens. Chitinases hydrolyze chitin components in pathogen cell walls, inhibiting fungal spore germination and germ tube elongation. They also inhibit pathogen growth by degrading newly synthesized chitin at the ends of hyphae, disrupting the deposition of new cellular substances and hindering hyphal extension.

—Enhancing plant defenses. Chitinases produce chito-oligosaccharides when degrading chitin components in pathogen cell walls. Chitosan oligosaccharides not only inhibit the invasion and spread of pathogens, hindering their growth, but also act as elicitors, acting as signaling factors in plant defense responses, rapidly initiating them and inducing plant cells to respond to pathogen invasion. They regulate the activity of disease-resistance-related enzymes such as peroxidase (POD), polyphenol oxidase (PPO), superoxide dismutase (SOD), and phenylalanine ammonia lyase (PAL), producing antimicrobial substances such as phytoalexins and phenolic compounds. These substances increase the levels of pathogenesis-related proteins in plants, enhancing disease resistance.

—They also synergize with other plant defense enzymes, cell wall-degrading enzymes, plant pathogenesis-related proteins, fungicides, and other biocontrol agents, enhancing plant disease resistance.