Hydrolyzes chitin and plays a role in defense against fungal pathogens containing chitin. Its overexpression confers enhanced resistance to sheath blight pathogen (R.solani). Random endo-hydrolysis of N-acetyl-beta-D-glucosaminide (1->4)-beta-linkages in chitin and chitodextrins. Expressed in roots, sheaths and meristems. Belongs to the glycosyl hydrolase 19 family. Chitinase class I subfamily.