Basic research on virus spread identifies a family of proteins that regulate vesicle trafficking and virus infection in plants.
CALS Impact Statement
Plant viruses invade a susceptible host to cause disease by transporting their genomes across the barrier of the plant cell wall. Doing this requires a unique class of proteins made by the virus, termed movement proteins. This process serves as a model for the transport of molecular complexes between plant cells, and hence for the mechanism of cell-cell communication in plants. Our studies of geminivirus movement lead to the unexpected identification of a small gene family in plants, which regulate vesicle trafficking and were thought to be found only in the nervous systems of animals. We have found that one member of this family regulates both the formation of vesicles at the plasma membrane (termed `early endosomes`) and the transport of different virus movement proteins across the plant cell wall. Our analyses also show the members of this gene family regulate the formation of different vesicle populations at different stages in plant growth and development. Thus, our research: (1) has established that a vesicle recycling pathway regulates the transport of virus genomes and cell-cell communication between plants cells; and (2) is defining the functions of the different members of this gene family of vesicle trafficking proteins in regulating plant cell growth and development.
A fundamental issue in virology is defining the molecular and cellular events, which underlie pathogenesis and lead to disease. For plant viruses, a key element of this disease potential is their ability to cross the barrier of the plant cell wall to invade the host. Our goal is to understand this process, and use this knowledge both to develop rational anti-viral strategies, and to identify the cellular transport pathways that regulate cell-cell communication in plants.
Our lab uses the model plant Arabidopsis thaliana and two model plant viruses: the DNA geminivirus Cabbage leaf curl virus (CaLCuV), and the RNA tobamovirus Tobacco mosaic virus (TMV). Using the approaches of molecular genetics, biochemistry, cell biology and genomics, we have established how geminiviruses move their DNA genomes within, and between, plant cells. We also discovered a class of proteins in plants, which were thought to only be found in the animal nervous system, and these have identified an endosomal recycling pathway, which acts to transport viral genomes to and across the plant cell wall. Building on this knowledge, our current research is focused on the mechanisms of nuclear shuttling and of vesicle trafficking in plant cells, both in terms of how these pathways regulate plant growth and development, and how viruses usurp these pathways to infect the plant and cause disease.
By addressing fundamental questions in viral pathogenesis and cell function in plants, our basic research has, and will continue to impact both the economic problem of crop losses due to viral disease, and the critical question of how vesicle trafficking regulates virus spread and development in both animals and plants. Virus infections cause devastating crop losses worldwide. Geminiviruses, in particular, are emerging viruses that destroy a range of nutritionally and economically important crops from maize and cassava in Africa, to tomatoes along the Mediterranean basin, cotton in Egypt and Asia, and beans, pumpkin and squash in the U.S., Latin America, and the Carribean. Beyond geminiviruses, all plant viruses must move cell-to-cell through plasmodesmata to invade the host plant. Transport through plasmodesmata is also critical for nutrient transport to the developing parts of the plant, including fruits, seeds and tubers (e.g. potatoes, cassava), and in regulating plant development and plant defenses against pathogen attack. Identifying key players, such as synaptotagmins, which regulate transport through plasmodesmata, will provide novel means to improve the nutritional quality of crop species and their resistance to infection by viral, bacterial and fungal pathogens. Our research on plant synaptotagmins also points to plants having adapted an evolutionary conserved endocytic pathway, which is important in the spread of cancer-causing animals viruses and in controlling animal development. Research on plant synaptotagmins will inform studies on how HIV (the cause of AIDS) and other retroviruses spread in humans to cause cancer, and how positional information is established in animal development.
Plant cell biology and development
funding source description
National Institutes of Health
Proposals are currently pending at NSF and BARD to further support our research.