MOLECULAR-CLONING AND CHARACTERIZATION OF A PEA CHITINASE GENE EXPRESSED IN RESPONSE TO WOUNDING, FUNGAL INFECTION AND THE ELICITOR CHITOSAN

The fungicidal class I endochitinases (E.C.3.3.1.14, chitinase) are as sociated with the biochemical defense of plants against potential path ogens. We isolated and sequenced a genomic clone, DAH53, corresponding to a class I basic endochitinase gene in pea, Chil. The predicted ami no acid sequence of this chitinase contains a hydrophobic C-terminal d omain similar to the vacuole targeting sequences of class I chitinases isolated from other plants. The pea genome contains one gene correspo nding to the chitinase DAH53 probe. Chitinase RNA accumulation was obs erved in pea pods within 2 to 4 h after inoculation with the incompati ble fungal strain Fusarium solani f. sp. phaseoli, the compatible stra in F. solani f. sp. pisi, or the elicitor chitosan. The RNA accumulati on was high in the basal region (lower stem and root) of both fungus c hallenged and wounded pea seedlings. The sustained high levels of chit inase mRNA expression may contribute to later stages of pea's non-host resistance.