Infections with some plant-pathogenic viruses not only make the host plants more attractive for aphids, but also increase the rate of aphid growth and reproduction. This may represent active manipulation of plant metabolism by viruses, which rely on insects for their transmission from one plant to another. However, although numerous studies have demonstrated altered aphid growth on virus-infected plants, very little is known about the molecular mechanisms that underlie this phenomenon. Research using Arabidopsis thaliana (Arabidopsis), Myzus persicae (peach-potato aphid), and Turnip mosaic virus (TuMV) as a model system will be used to study the molecular biology of plant-aphid-virus interactions. Preliminary results show that Arabidopsis defense responses, which are normally turned on when aphids initiate feeding, are reduced in TuMV-infected plants. Further research will be directed at measuring virus-induced changes in plant metabolisms, identifying plant defense pathways that are manipulated by TuMV, and determining which of the eleven TuMV genes are required for shutting down anti-aphid defenses in Arabidopsis and other plant species.
TuMV, which is commonly transmitted by green peach aphids, is a serious pathogen of vegetable crops. Virus control in agricultural systems is complicated by the propensity of peach-potato aphids to develop insecticide resistance, as well as TuMV reservoirs in Arabidopsis and other weed species. Research on the interactions of Arabidopsis, peach-potato aphids, and TuMV interactions, will identify previously unknown aspects of plant metabolism that contribute to aphid attraction and reproduction. Such information can be used to improve the insect and virus resistance of crop plants through classical breeding and transgenic approaches. The proposed project also will contribute to training a new generation of students in plant molecular biology, biochemistry, and genetics. These students will be well-prepared for future careers in the plant biotechnology industry, academia, or government service.