Stewart Gray, PhD
Department of Plant Pathology
Research Interests
My research program focuses on understanding the relationships between plant viruses and their insect vectors. Specifically we work on luteoviruses and their aphid vectors. Research projects range from the mechanisms of aphid-virus interactions to epidemiology and disease management strategies. The luteoviruses are vectored specifically by different species of aphids. One research thrust is to understand the cellular and molecular mechanisms that determine the vector specific transmission. A working hypothesis is that virus-vector specificity involves an interaction between viral capsid proteins and membrane receptors on the aphid hindgut and salivary gland. Biochemical and genetic approaches are being used to identify and map domains of the two luteovirus capsid proteins that are involved in the transmission process.
The laboratory is also studying what the aphid is contributing to the virus transmission process. Several biotypes within the aphid, Schizaphis graminum, were identified that differ in their ability to transmit one or more strains of barley yellow dwarf virus. Sexual forms of four biotypes have been induced and are being crossed to generate aphid populations that can be used in genetic mapping studies. These populations coupled with a differential display analysis of tissue-specific gene expression in the parental populations should enable the identification of aphid genes and gene products that interact with virus proteins during the transmission process.
The other major research project the laboratory is currently involved with is a region study of barley yellow dwarf epidemiology and control in the southeastern United States. Current emphasis is placed on identifying the seasonal phenology of aphid vectors, virus spread into and within cereal crops, and impact of the disease on yield.