DIFFERENTIAL LEAF RESISTANCE TO INSECTS OF TRANSGENIC SWEETGUM (LIQUIDAMBAR STYRACIFLUA) EXPRESSING TOBACCO ANIONIC PEROXIDASE

Leaves of transgenic sweetgum (Liquidambar styraciflua) trees that exp ressed tobacco anionic peroxidase were compared with leaves of L. styr aciflua trees that did not express the tobacco enzyme. Leaves of the t ransgenic trees were generally more resistant to feeding by caterpilla rs and beetles than wild-type leaves. However, as for past studies wit h transgenic tobacco and tomato expressing the tobacco anionic peroxid ase, the degree of relative resistance depended on the size of insect used and the maturity of the leaf. Decreased growth of gypsy moth larv ae appeared mainly due to decreased consumption, and not changes in th e nutritional quality of the foliage. Transgenic leaves were more susc eptible to feeding by the corn earworm, Helicoverpa zea. Thus, it appe ars the tobacco anionic peroxidase can contribute to insect resistance , but its effects are more predictable when it is expressed in plant s pecies more closely related to the original gene source.