Reduced levels of class 1 reversibly glycosylated polypeptide increase intercellular transport via plasmodesmata

Maize and Arabidopsis thaliana class 1 reversibly glycosylated polypeptides (C1RGPs) are plasmodesmata-associated proteins. Previously, over-expression of Arabidopsis C1RGP AtRGP2 in Nicotiana tabacum was shown to reduce intercellular transport of photoassimilate, resulting in stunted, chlorotic plants, and inhibition of local cell-to-cell spread of tobacco mosaic virus (TMV). Here, we used virus induced gene silencing to examine the effects of reduced levels of C1RGPs in Nicotiana benthamiana. Silenced plants show wild-type growth and development. Intercellular transport in silenced plants was probed using fluorescently labeled TMV and its movement protein, P30. P30 shows increased cell-to-cell movement and TMV exhibited accelerated systemic spread compared to control plants. These results support the hypothesis that C1RGPs act to regulate intercellular transport via plasmodesmata.