Symptom development, virus multiplication, and distribution of tomato mosaic virus strains L and LS1were compared at 22 and 32 °C in the C4plantGomphrena globosa. In inoculated leaves, LS1accumulation was much lower at 32 °C compared with 22 °C, whereas the levels of L were similar at both temperatures. At 22 °C, spread of L and LS1from inoculated to uninoculated leaves (systemic movement) was dependent on the stage of plant development and the leaf inoculated. Under all conditions tested, LS1accumulated at a much lower level than L. Under specific conditions of leaf and plant age, LS1was confined to the inoculated leaf, whereas L moved systemically in all experiments. In a mixed infection with tobacco mosaic virus U1strain, LS1did not affect movement of U1within the inoculated leaf but inhibited systemic spread. InGomphrena, the single amino acid difference in the 30-kDa movement protein of LS1relative to L induced plant resistance to systemic spread of virus.Keywords: systemic movement, local lesion.