Putting the squeeze on PDs - Reticulons, plasmodesmata and viral trafficking in plants.

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Plasmodesmata, the small pores that interconnect plant cells, are enigmatic structures central to plant development, physiology and pathology. Many substances, including small solutes, signalling molecules and proteins can move through plasmodesmata, but the control of movement is poorly understood. Plant viruses exclusively use plasmodesmata to move between plant cells during infection and all plant viruses encode specialised movement proteins that interact with plasmodesmata to allow passage of the viral genome. During infection the plasmodesmata become transiently 'gated' by an unknown interaction. Plasmodesmata contain a central structure, the desmotubule, that is comprised of tightly appressed ER membranes. At only 15 nm in diameter, the desmotubule is one of the most tightly constricted membrane structures known in nature, and is a prime target for viral movement proteins during infection.

We have recently obtained data to suggest that the reticulons, a specific class of membrane tubulating proteins, may be involved in the formation of desmotubules during cell plate formation. We hypothesise that reticulons function to remodel the cortical ER at the end of cell division when plasmodesmata are being laid down between adjoining cells, and that these proteins link the desmotubule to oether unknown proteins within the plasmodesmal channel.

This project will use a unique combination of virology, biochemistry, cell biology and state-of-the-art imaging to study how reticulons are involved in the biogeneisis of plasmodesmata, and how they interact with viral movement proteins. The overall goal, through increased understanding of plasmodsmal development and structure, is to develop strategies for limiting virus spread in plants.

This project will examine how plant cells construct plasmodesmata, the small communication channels between cells, and will study the mechanisms by which plant viruses interact with these pores to facilitate their spread in the plant. Plant viruses are a serious worldwide threat, yet little is known of the mechanism of cell-cell passage. This is a basic project and the main audience for the work is expected to be the scientific community. However, the spread of viruses is a topical area in the media and we will endeavour to publicise our work through a number of distinct routes. These include:

1. Publication of articles in the popular press. The strong imaging component of this work lends itself to the production of new images of virus movement that can be used by the media. One of us (KO) has previous experience in dealing with popular press and with documentary programmes, such as 'Horizon'. KO has also been approached by the BBC with a view to acting as a consultant on a newly commissioned series on plant function. Images from the current proposal are likely to find their way rapidly into mainstream reports on virus infection. We will also publish in BBSRC literature and in popular journals such as New Scientist and The Scientist. Through the respective press offices at Edinburgh and Oxford Brookes, we will release appropriate news articles for dissemination to the popular press.

2. Influence on the agricultural sector. A major goal of the project is to understand the process of virus movement such that strategies may be developed for impeding cell-cell transport of viruses in economically important plants. The viruses being used as 'models' in the study are also important crop pathogens, and the results are likely to be transferable to major crop families such as the Solanaceae (e.g. potato, tomato). KO has strong links with the agricultural sector and we will inform applied crop biologists and breeders of our findings at key national and international symposia.

3. Influence on policy makers. Crop protection in a changing climate is a major issue of current concern. As temperatures increase in the UK, so also will the virus pathogen profiles of the principal crop species. KO has strong links with Scottish Government-funded virologists through institutes such as SASA (Dr. Christophe Lacomme) and The James Hutton Institute (Dr. Lesley Torrance and Prof. Misha Taliansky). Regular meetings with policy-led scientists will ensure that our work is disseminated appropriately across a broad spectrum of plant pathologists and Government representatives.

4. Intellectual property release. Two areas are worth specific note in this area of Impact. (i) The project, through the development of novel imaging methods and approaches, has the potential to generate IP related to developments in microscopy and imaging. In this respect, both PIs will work closely with their respective technology transfer companies, ERI (Edinburgh) and RBDO (Oxford), to ensure a timely protection of IP as the project develops.

5. Outreach activities. Both PIs are involved in regular outreach activities, including the supply of images to the Gatsby Foundation (Schools), presentation of talks and demonstrations at national science festivals (e.g Edinburgh Science Festival), The Royal Society of Edinburgh (KO) and The Royal Microscopy Society (CH).

Our Impact plan will exploit these four areas of engagement to ensure maximum publicity and dissemination of the science conducted in the project.