This protein functions as a defense against chitin containing fungal pathogens. This endochitinase also exhibits exochitinase activity, i.e. it is capable of hydrolyzing chito-oligosaccharides, including chitobiose. Random endo-hydrolysis of N-acetyl-beta-D-glucosaminide (1->4)-beta-linkages in chitin and chitodextrins. Intercellular fluid of leaves. Accumulates in leaves during infection. By fungal infection. Belongs to the glycosyl hydrolase 18 family. Chitinase class II subfamily.