Plant intercellular channels, plasmodesmata (PD), are critical for regulating communication within and between plant tissues. The major approach of the PI is to study the perturbation of PD by plant viruses, pirates of PD channels. Specific virus encoded proteins, movement proteins (MPs), are essential for infectious viral spread via PD. The proposed research will: 1) Continue analysis of the movement protein of tobacco mosaic virus (TMV MP). Early studies defined 4 functional regions of TMV MP. Recent work suggests 2 additional functional domains, the C-terminal half of TMV MP is essential for movement via PD, and the N-terminal 2/3 is essential for binding to the cytoskeleton for intracellular trafficking towards PD. The proposed studies will precisely define signal sequences for : a) cytoskeleton localization, b) gating (opening) of PD, and c) transport through PD (may be the same as """"""""b""""""""). 2) Initiate studies on movement proteins of turnip crinkle virus (TCV). There are 2 MPs of TCV, P8 and P9, and their small size (8 and 9 kDa) makes them especially attractive to define signal sequences (as above for TMV MP) for trafficking via PD. Additionally, TCV infects Arabidopsis thaliana, one of the most widely used species for plant research. Thus, she will begin a second approach to analyze cell to cell trafficking at the whole plant level. Viral MPs likely interact with different plant cellular components that are regulated according to internal, as well as externally induced, patterns of growth and development. We will monitor intercellular trafficking (via fluorescent tracers) in the shoot, where plant viruses attack and were significant alterations in growth and morphogenesis occur. The small physical size of Arabidopsis thaliana makes it highly suitable to monitor whole organ trafficking patterns. These studies complement studies on viral MPs since they will provide critical information on global trafficking patterns as a function of plant age, tissue type, and growth conditions. Such studies will allow better design of experimental strategies to assess viral induced alterations in PD traffic, and will have direct application to understanding why some tissues, like meristems, have reduced capacity for viral spread.
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