Plant chitinases--regulation and function.

The aim of this review is to present the current state of knowledge on plant chitinases and their regulation and function. Chitinases are up-regulated by a variety of stress conditions, both biotic and abiotic, and by such phytohormones as ethylene, jasmonic acid, and salicylic acid. Like other PR proteins, chitinases play a role in plant resistance against distinct pathogens. Moreover, by reducing the defence reaction of the plant, chitinases allow symbiotic interaction with nitrogen-fixing bacteria or mycorrhizal fungi. However, recent investigations have shown that these enzymes are also involved in numerous physiological events. The involvement of chitinases in development and growth processes is also described.