Submitted to: Journal of Experientia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/1998
Publication Date: N/A
Citation: N/A Interpretive Summary: Further study is needed in order to understand how sources of plant resistance to insects operate, in order to most effectively use them for insect control. An enzyme that appears to promote resistance to insects in tobacco was introduced into a distantly related plant, sweetgum. Leaves of the genetically engineered trees were generally more resistant to feeding by several insect species compared to leaves from the normal trees. However, in one case the leaves from the genetically engineered trees were more susceptible to an insect that doesn't normally feed on the tree. This information indicates the enzyme probably plays a general role in insect resistance, but it must be tested in each plant species of interest to make sure it produces the desired effect.
Technical Abstract: Leaves of transgenic sweetgum (Liquidamber styraciflua) trees that expressed tobacco anionic peroxidase were compared to leaves of L. styraciflua trees that did not express the enzyme for resistance to insects. Leaves of the transgenic trees were generally more resistant to feeding by caterpillars and beetles than wild type leaves. However, as for past studies with transgenic tobacco and tomato expressing the tobacco anionic peroxidase, the degree of relative resistance depended on the size of insect used and the maturity of the leaf. Decreased growth of gypsy moth larvae appeared mainly due to decreased consumption, and not changes in the nutritional quality of the foliage. Transgenic leaves were more susceptible to feeding by the corn earworm, Helicoverpa zea. Thus, it appears the tobacco anionic peroxidase can contribute to insect resistance, but its effects are more predictable when it is expressed in plant species more closely related to the original gene source.