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Title: PEST AND DISEASE RESISTANCE ENHANCED BY HETEROLOGOUS SUPPRESSION OF A NICOTIANA PLUMBAGINIFOLIA CYTOCHROME P450 GENE CYP72A2

Author
item Smigocki, Anna
item HAYMES, SNEZANA - TOWSON UNIVERSITY
item WILSON, DENNIS - UNIVERSITY OF MD

Submitted to: Biotechnology Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/4/2004
Publication Date: 12/1/2004
Citation: Smigocki, A.C., Haymes, S.D., Wilson, D. 2004. Pest and disease resistance enhanced by heterologous suppression of a nicotiana plumbaginifolia cytochrome p450 gene cyp72a2. Biotechnology Letters. 26:1809-1814.

Interpretive Summary: In order to increase yields and reduce the use of chemical pesticides, there is a need to develop plants that are resistant to predatory insects and microbial pathogens. We used genetic engineering approaches to produce genetically modified plants that had changed levels of chemical compounds that are naturally found in plants. These plants were fed to insects (tobacco hornworm larvae); the insects ate 35-90% less leaf material than insects fed with the normal, non-genetically modified leaves. In addition, there was less disease on the modified plants when they were inoculated with a bacterial pathogen. The unaltered plants inoculated with the bacteria always had more disease. We conclude that the changed levels of the natural plant compounds in the genetically modified plants limited the disease and insect damage to the plants. This information will be used by scientists to identify the active compounds and increase our knowledge of plant defense mechanisms that will lead to novel strategies for controlling plant pests and diseases thus reducing the usage of harmful chemicals.

Technical Abstract: The functional role of the Nicotiana plumbaginifolia cytochrome P450 gene CYP72A2 was investigated in transgenic plants. N. tabacum plants transformed with a sense or antisense CYP72A2 construct exhibited reduced heights, branched stems, smaller leaves and deformed flowers. Western blot analysis revealed reduced levels of a 58kDa protein corresponding to CYP72A2 suggesting that the CYP72A2 homolog was suppressed in the sense and antisense plants. Transgenic plants had increased resistance to Manduca sexta larvae that consumed about 35 to 90% less of transgenic vs. control leaves. Pathogenic Pseudomonas syringae pv. tabaci induced a disease-limiting hypersensitive response followed by delayed and decreased disease symptom development in the transgenics. CYP72A2 gene mediated resistance suggests that the plant-pest or -pathogen interactions may have been modified by changes in bioactive metabolite pools.