Required for the maintenance and/or establishment of both the shoot and root meristems, probably by controlling the expression of the meristem genes and of genes required for auxin responses. Involved in the development of the basal pole and in auxin-mediated root and vascular development in the embryo (By similarity). Confers sensitivity to turnip mosaic virus (TuMV) probably by promoting viral movement and multiplication via interaction with TuMV VPg (Probable). Self-interacts and probably forms heteromers (By similarity). Binds to VPg of pea seed borne mosaic virus (PSbMV), turnip mosaic virus (TuMV) and lettuce mosaic virus (LMV), but not with VPg of tobacco etch virus (TEV), cowpea mosaic virus (CPMV), tomato black ring virus (TBRV) and grapevine fan leaf virus (GFLV).