Plasmodesmata: genetic control of cell-to-cell communication during plant defence

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Like animals, plants suffer all manner of diseases caused by various fungal, bacterial and viral pathogens. When a fungal or bacterial pathogen attacks a plant, the battlefront occurs initially at a single cell. One means by which a plant can fight off the pathogen is to initiate a process that results in death of the cell that is being attacked, preventing the pathogen from gaining nutrients from this cell and spreading. This process involves the generation of many toxic molecules and it is crucial that the cells surrounding the attacked cell do not suffer the same fate. Plant cells are connected to their neighbouring cells by channels called plasmodesmata. These channels are like open doorways into neighbouring cells and small molecules can simply pass from cell to cell. The question then is how a dying cell stops toxic molecules leaking out into its neighbours? Does the cell close the doors into its neighbours? We know that plasmodesmata can open and close to control the movement of signals between cells when a plant is exposed to cold or when the plant undergoes a developmental transition. We want to investigate whether these doors close when a pathogen attacks and how this happens.Recently, many new proteins that are located at plasmodesmata have been identified. One of these is a receptor for fungal chitin and causes plasmodesmata to close when a fungus is detected. I will examine why plasmodesmata close when a pathogen is perceived by microscopic analysis of living tissue that is under attack from different pathogens. I will also determine how plasmodesmata close by biochemical and genetic identification of proteins that required for this response. By establishing when and how plasmodesmata open and close when a pathogen attacks we will be able to understand a very important mechanism that a plant uses to fight disease. The last objective of this programme will begin to explore this phenomenon in rice with the aim of understanding how this global food crop uses this mechanism to fight off pathogens. Understanding these mechanisms will enable us to exploit them to help plants fight disease, placing us in a strong position to combat the impact of increased prevalence of plant disease that is likely to arise from global climate changes.