Transgenic tomato plants expressing a Lycopersicon chilense chitinase genedemonstrate improved resistance to Verticillium dahliae race 2

An acidic, endochitinase gene (pcht28) isolated from Lycopersicon chilense was introduced into tomato (L. esculentum) through Agrobacterium-mediated t ransformation, using the CAMV 35S promoter. Transgenic plants demonstrated a high level of constitutive expression of pcht28 and chitinase enzyme acti vity. Kanamycin-resistant R1 plants (resulting from self-pollination of tra nsgenic plants) as well as R2 plants were evaluated for their tolerance to Verticillium dahliae (race 1 and 2 for R1 plants and race 2 for R2 plants) in the greenhouse. They demonstrated a significantly (P<0.05) higher level of tolerance to the fungi compared to the nontransgenic plants, as measured by foliar disease symptoms, vascular discoloration, and vascular discolora tion index. The transgenic plants produced in this study represent a source of genetic resistance to Verticillium dahliae.