Plant Molecular Biology 28: 105-111, 1995. © 1995 Kluwer Academic Publishers. Printed in Belgium. 105 Molecular cloning and characterization of a pea chitinase gene expressed in response to wounding, fungal infection and the elicitor chitosan Ming-Mei Chang 1, Daniel Horovitz 2, David Culley 3 and Lee A. Hadwiger 3,, 1 Department of Biology, State University of New York, Geneseo, NY 14454, USA; 2Current Address: Department of Molecular Immunology, Immune x Corp, Seattle, WA 98101; 3 Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430, USA (*corresponding author) Received 17 February 1995; accepted in revised form 17 February 1995 Key words: DNA sequence, pathogenesis-related protein, Fusarium solani, compatible pathogen, incompatible pathogen, elicitor, chitosan Abstract The fungicidal class I endochitinases (E.C.3.3.1.14, chitinase) are associated with the biochemical de- fense of plants against potential pathogens. We isolated and sequenced a genomic clone, DAH53, corresponding to a class I basic endochitinase gene in pea, Chil. The predicted amino acid sequence of this chitinase contains a hydrophobic C-terminal domain similar to the vacuole targeting sequences of class I chitinases isolated from other plants. The pea genome contains one gene corresponding to the chitinase DAH53 probe. Chitinase RNA accumulation was observed in pea pods within 2 to 4 h after inoculation with the incompatible fungal strain Fusarium solani f. sp. phaseoli, the compatible strain F. solani f.sp. pisi, or the elicitor chitosan. The RNA accumulation was high in the basal region (lower stem and root) of both fungus challenged and wounded pea seedlings. The sustained high levels of chitinase mRNA expression may contribute to later stages of pea's non-host resistance. Introduction Pathogenesis-related proteins (PR proteins) ac- cumulate in plants in response to pathogens and abiotic stresses. Included in this class of proteins are the fungal cell wall degrading enzymes chiti- nase and fl-l,3-glucanase. Endochitinases (E.C. 3.2.1.14, chitinase) from plants catalyze the hy- drolysis of chitin, a fl-l,4-1inked homopolymer of N-acetyl-D-glucosamine, which is a major com- ponent of the cell walls of many fungi [2]. Chiti- nase is induced in plants in response to fungal [6, 12], bacterial [3] and viral infections [ 11, 15, 28], the hormone ethylene [1, 4] and fungal elicitors [ 10, 16, 22]. Chitinase in combination with fl-l,3- glucanase has antifungal activity [18, 24]. Six classes of plant chitinases have been de- scribed based on those of tobacco and relate to The nucleotide sequence data reported will appear in the EMBL, GenBank and DDBJ Nucleotide Sequence Databases under the accession number L37876