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Submitted to: BARC Poster Day
Publication Type: Abstract Only Publication Acceptance Date: 3/19/1998 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Cytochrome P450 monooxygenases are heme dependent mixed function oxidases that utilize NADPH or NADH and molecular oxygen to produce functionalized organic products. In higher plants, P450 monooxygenases are involved not only in the biosynthesis of secondary metabolites but also in the metabolism of zenobiotics including herbicides and insecticides. Full length sequence of P450 cDNA clone was derived using 5'RACE from N. plumbaginifolia carrying a heat-shock inducible isopentenyl transferase (ipt) gene involved in cytokinin biosynthesis (LaRosa and Smigocki, 1996). In this study, we investigated the effect of insect feeding and mechanical wounding on P450 gene expression using tobacco plants containing a wound-inducible ipt gene construct, PI-II ipt (Smigocki et al., 1993, Smigocki, 1996). Northern blot analysis showed a 4- to 6-fold higher levels of induction after 6 to 12 hr of mechanical wounding in ipt-transformed leaves at various stages of development in comparison to a 2- to 3-fold induction from wounded but untransformed leaves. Leaves infested with third instar tomato hornworm (Manduca sexta) larva elicited a response similar to that caused by mechanical wounding. The response to both treatments was systemic and was detected maximally in the leaf immediately above the damaged leaf. P450 transcripts were not detected in flower buds, flowers and seed pods. The role of P450 in plant defense responses will be explored by transforming plants with various P450 sense and antisense constructs. |
