Viral infections in crop plants can cause major losses in crop productivity. Despite more than a century of research on plant-virus interactions, control of viral infection remains a challenge to plant health. Unlike most bacterial and fungal plant pests, most viruses depend on insects who serve as "vectors" to transmit the virus to the plant cell, often through sucking mouthparts. Thus, a complex three-way relationship develops in which the host plant mounts an immune response that is countered by the virus and its insect vector. Understanding how and when this three-way interaction occurs is thus essential to identify control points of the viral disease. The goals of this research program are to investigate plant responses to infection and to uncover unique collections of genes and biochemical pathways that drive plant-virus-insect interactions in tomato. The results will provide candidate genes for engineering new strategies of virus management, and will establish the tomato-Potyvirus-aphid system as a model for studying three-way disease interactions. The research also provides novel insight into how the natural variation of viral disease is mediated within and across domesticated and wild tomato. High school and undergraduate students will participate directly in research to learn about the genomic-level science underlying viral disease in plants. The project will also encourage cross-disciplinary communication in plant genomics by hosting a summer discussion group at the University of California-Davis focused on plant genomics research.
Nearly every major cropping system faces threats from plant-infecting viruses, and most plant viruses rely on insect vectors for transmission. Although numerous studies have shown that viruses can manipulate plant metabolism to promote viral acquisition and transmission by vectors, few have examined the underlying molecular mechanisms mediating plant-virus-vector interactions and none have developed a system-level understanding of this process. This work builds on the recent discovery that plant viruses respond actively to the presence of insect vectors via host plant-derived signals, promoting insect performance and transmission through changes in plant chemistry. The aim of this project is to develop a detailed understanding of the genes and pathways that underlie viral "recognition" of insect vectors and activation of processes within the host plant that facilitate transmission by insect vectors. Transcript profiling, metabolomics, and bioinformatics will be used to develop a co-expression network and identify key regulators of this phenomenon. Introgression-mapping lines in combination with knockouts will be used to functionally characterize key regulators mediating plant-virus-vector interactions within and across plant species. All data and resources generated in this project will be made accessible to the public through the project website and through long-term data repositories.