The Plasmodesmata Location Of Rice Stripe Virus Movement Protein And Its Effects On Motor Function

Rice stripe virus (RSV) is the type member of genus Tenuivirus. It is transmitted by the Laodelphasx cstriatellus and causes a serious viral disease on rice in China, resulting in huge economic losses in rice production. RSV has a genome of four single-stranded RNAs, encoding seven proteins, including pc4, a32.5kDa protein, encoded by the complementary strand of RNA4.It is usual to distinguish two types of virus movement. Short distance movement between cells (cell-to-cell movement) occurs through plasmodesmata (PD) and long distance transport depends on the vascular system. Short distance movement needs the assistance of a movement protein (MP/pc4). According to the importance of MP in RSV infection process, we studied the PD-localization and its effects on motor function.Results show that:A transmembrane (TM) domain spanning aa106-123of pc4was identified and shown to be essential for localization of pc4to plasmodesmata (PD) and for its ability to recover the movement of movement-deficient PVX, but did not effect its localization of chloroplast. Analysis of alanine-scanning mutants showed that M116A and G120A had the same localization to wild-type pc4, being localized at PD and chloroplasts, but all other mutants were only localized at chloroplasts and not at PD. Mutants that could not be localized at PD had no ability to recover PVX-GFP△p25movement, in spite of G123A having little the ability, which indicate that PD localization is crucial for the function of pc4as a movement protein. Strangely, mutants M116A and G120A had the ability to locate at PD and to bind single-stranded RNA but had lost the ability to move, which indicate that properties other than PD localization and nucleotide binding ability may be needed for the function of pc4as a movement protein.