Probably involved in hypersensitive reaction upon Xanthomonas campestris infection. Random endo-hydrolysis of N-acetyl-beta-D-glucosaminide (1->4)-beta-linkages in chitin and chitodextrins. Optimum pH is 4.8. Expressed in cells surrounding embryos, stems, seedlings, pollen, roots, shoots, inflorescence, flowers, siliques and leaves (PubMed:11525512, PubMed:19420714). Present in seedpods and seed embryos, but not in roots, inflorescence stems, leaves and flowers (PubMed:9426222). Expressed during somatic embryogenesis in nursing cells surrounding the embryos but not in embryos. Accumulates in mature pollen and growing pollen tubes until they enter the receptive synergid, but not in endosperm and integuments. In adult plants, present in hydathodes, stipules, root epidermis and emerging root hairs. Accumulates rapidly and transiently in leaves after inoculation with Xanthomonas campestris (PubMed:9426222). Slightly repressed by wounding (PubMed:19420714). Belongs to the glycosyl hydrolase 19 family. Chitinase class I subfamily. Extended N-terminus.