The role of post-Golgi transport pathways and sorting motifs in the plasmodesmal targeting of the movement protein (MP) of Ourmia melon virus (OuMV)

Natali Ozber; Paolo Margaria; Charles T. Anderson; Massimo Turina; Cristina Rosa

Moreover, the redistribution of OuMV MP into the same smaller vesicles as the TGN marker upon low dose BFA treatment suggests that MP exhibits BFA sensitivity only at the TGN, but not at the Golgi. Dependence on the canonical secretory pathway varies between plant viruses (reviewed by Pitzalis and Heinlein, 2017) . Whereas the secretory pathway is not involved in targeting of the Cowpea mosaic virus (CPMV, genus et al., 2007) . In addition, OuMV MP was not associated with MVBs/PVCs in the absence or presence of Wm (Fig. 1C) , confirming that MP trafficks in the first stages of vesicular trafficking, but not in MVB/PVC-to-vacuole pathway, in contrast to CaMV MP (Carluccio et al., 2014) and PTMV TGB2 (Haupt et al., 2005) , which co-localize with ARA7-positive MVBs/PVCs. Although OuMV MP showed sensitivity to Wm, this response was different from that of MVBs/PVCs. Based on the finding that OuMV MP localizes to the TGN and does not enter either in the canonical secretory or MVB/PVCto-vacuole pathways, we hypothesize that MP constitutively cycles between the plasma membrane and the TGN.