Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Biology

Supervisor(s)

Dr. Abdelali Hannoufa

Abstract

Carotenoid cleavage dioxygenases (CCDs) are responsible for the cleavage of carotenoids into smaller compounds, including apocarotenoids. The volatile apocarotenoids produced have demonstrated a repellent and feeding deterrent effect with some insects. To understand the formation of apocarotenoids and the effect on insect oviposition and feeding preference, I investigated the role of CCD genes in plant-insect interactions by comparing four different transgenic genotypes that over-express CCD and the respective wild-type (WT) for two model plants. CCD4 and CCD1 genes were overexpressed in Arabidopsis thaliana (Arabidopsis) and LeCCD1-1 and LeCCD1-2 genes were overexpressed in Solanum lycopersicum (tomato), Oviposition choice bioassays with the cabbage looper moth (Trichoplusia ni) and greenhouse whitefly (Trialeurodes vaporariorum) showed a significantly greater oviposition of both insects on the transgenic plants in comparison to WT plants, whereas feeding assays with T. ni larvae indicated no preference toward CCD over-expressing plants. The findings suggest that manipulating the carotenoid-based volatile profile of plants could provide a novel strategy to attract pest insects away from the crops towards these trap plants. This would also contribute to a reduction in the dependence of chemical pesticides and reduce the associate negative environmental effects of their use.


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