Molecular mechanism of BjCHI1-mediated plant defense against Botrytis cinerea infection.

Plant chitinases are a group of proteins associated with defense against pathogen attack. BjCHI1 is the first characterized chitinase containing two chitin binding domains (CBDs). Investigations have shown that BjCHI1 inhibits growth of fungal phytopathogens and agglutinates Gram-negative bacteria. Our recent studies revealed that expression of BjCHI1 mRNA is largely induced upon infection of Botrytis cinerea via a R2R3-MYB transcription factor BjMYB1 interacting with a W box-like element (Wbl-4) in the BjCHI1 promoter. The enhanced expression pattern of BjMYB1 was similar to that of BjCHI1 and associated with resistant phenotype against B. cinerea. These findings suggest that BjCHI1 is involved in host defense against fungal attack through interaction with BjMYB1. Here, we review the recent studies on BjCHI1 and propose a model of BjCHI1-mediated plant defense against fungal attack.