Poster: Secondary Metabolism
Abs #
289: Induced expression of a cytochrome P450 Gene in the midgut of Helicoverpa armigera by gossypol
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Presenter: |
Chen, Xiao-Ya , xychen@iris.sipp.ac.cn |
Authors | Chen, Xiao-Ya (A) Mao, Yong-Bo (A) (B) Jiang, Rong-Jing (B) Huang, Yong-Ping (B) | | Affiliations: |
(A): National Key Laboratory of Plant Molecular Genetics
(B): Laboratory of Laboratory of Environmental Biology and Molecular Ecology,
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Certain plant secondary metabolites are toxic to herbivores, thus are important in protecting plants from pests. Other plant secondary components, particularly certain volatiles, may act as signal molecules in plant-insect interactions. On the other hand, insects have developed their detoxification systems in long evolution. The cytochrome P450 monooxygenases are one of the most important components in detoxification systems of insects.
Gossypol and related sesquiterpene aldehydes are constitutively present in glands of most cotton cultivars. Although these sesquiterpene aldehydes are toxic to many organisms, cotton ball worms (Helicoverpa armigera) consume plant tissues that contain gossypol. This indicates that the caterpillars may have a detoxification system that transforms gossypol. We have isolated two Helicoverpa armigera P450 cDNAs (YB1, YB2). YB2 is highly and constitutively expressed in midgut and the expression in brain is undetectable. On the contrary, YB1 is highly expressed in brain and fatty body, but only weakly midgut. However, YB1 expression in midgut was induced by 0.2% gossypol included in the food. The transcript level increased 10 hours after treatment, and peaked after 20 hours. Other chemicals tested, including trans-cinnamic acid and b-caryophyllene, failed to induce YB1 expression. Interestingly, we found one of the plant volatiles suppressed the expression of YB1 in midgut. These results suggest that induced YB1 expression in midgut is a response of cotton ball worms to specific compounds, and some plant volatile chemicals act as signal molecules to suppress this pathway.
* For correspondence
