DNA Plant Technology Corp. said Thursday that tobacco plantsgenetically engineered to express an anti-fungal enzymeresisted fungal infections as well as plants treated with afungicide and had a 16 percent greater post-harvest weightthan chemically treated plants.

DNAP said the plants expressed a high level of chitinase, anenzyme that breaks down chitin, a structural component of thecell walls of fungi. Certain plants and bacteria normallyproduce chitinase, but in amounts and at times insufficient toprevent fungal infection.

DNAP engineered the tobacco plants to express a higher level ofchitinase by incorporating into them a gene isolated from astrain of Serratia marcescens bacteria. The company conductedfield trials at a quarter-acre site in California, comparingengineered tobacco plants with plants treated with Benlate, afungicide produced by Du Pont to control a common soil-bornepathogen, Rhizoctonia solani.

Harmful fungi are currently controlled by chemical fumigationof soil or by treatments of plants and harvested fruits withfungicides. The world market for such fungicides exceeds $1billion.

DNAP is awaiting U.S. Department of Agriculture approval toconduct field trials of tomatoes modified to produce chitinase.DNAP hopes to test the efficacy of chitinase in controlling post-harvest diseases, said John Bedbrook, DNAP's executive vicepresident and director of science. Botrytis fungus is the mostimportant cause of post-harvest rot.

The Cinnaminson, N.J., company has also successfully expressedchitinase in potatoes, lettuce and sugar beets, but has no plansfor field tests. Last July, DNAP received a U.S. patent on itschitinase technology.

DNAP stock (NASDAQ:DNAP) closed Thursday at $5.63, up 50cents.

-- Karen Bernstein BioWorld Staff

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