Effects of movement protein mutants on Ourmiavirus infection, and their co-localization with plant cytoskeleton and organelles
P. MARGARIA (1), C. Anderson (1), M. Turina (2), C. Rosa (1) (1) Pennsylvania State University, U.S.A.; (2) Institute for Sustainable Plant Protection, Italy

Plant viruses in the genus Ourmiavirus are peculiar, since they are possibly the results of a reassortment event between a narnavirus-like element from a plant-pathogenic fungus, and a plant tombusvirus. The acquisition of the movement protein from the parental plant virus might have represented the critical event for the evolution of a new plant-infecting virus. We generated 11 Ourmia melon virus (OuMV) MP mutants, and studied the effects on symptomatology, movement, subcellular localization, and tubule formation in protoplasts. We identified five OuMV mutants that were impaired for local and systemic infection in Nicotiana benthamiana and Arabidopsis thaliana, and two mutants showing respectively necrosis and pronounced mosaic symptoms in N. benthamiana. GFP fusion constructs of movement-defective MP alleles failed to localize in distinct foci at the cell wall, whereas a GFP fusion with wild-type MP mainly co-localized with plasmodesmata and accumulated at the periphery of epidermal cells. The movement-defective mutants also failed to produce tubular protrusions in protoplasts isolated from infected leaves, suggesting a link between tubule formation and the ability to move. By dual imaging of GFP:MP fusions and fluorescent markers linked to cellular cytoskeleton components and organelles, and by treatment with chemical inhibitors, we are investigating the subcellular localization of the MP alleles, and the requirements for intracellular movement and successful infection. 

Abstract Number: P7-191
Session Type: Poster