MOVEMENT OF TOMATO MOSAIC-VIRUS STRAINS IN GOMPHRENA-GLOBOSA AS RELATED TO TEMPERATURE SENSITIVITY AND PLANT-RESISTANCE

Symptom development, virus multiplication, and distribution of tomato mosaic virus strains L and LS(1) were compared at 22 and 32 degrees C in the C-4 plant Gomphrena globosa. In inoculated leaves, LS(1) accumu lation was much lower at 32 degrees C compared with 22 degrees C, wher eas the levels of L were similar at both temperatures. At 22 degrees C , spread of L and LS(1) from inoculated to uninoculated leaves (system ic movement) was dependent on the stage of plant development and the l eaf inoculated. Under all conditions tested, LS(1) accumulated at a mu ch lower level than L. Under specific conditions of leaf and plant age , LS(1) was confined to the inoculated leaf, whereas L moved systemica lly in all experiments. In a mixed infection with tobacco mosaic virus U-1 strain, LS(1) did not affect movement of U-1 within the inoculate d leaf but inhibited systemic spread. In Gomphrena, the single amino a cid difference in the 30-kDa movement protein of LS(1) relative to L i nduced plant resistance to systemic spread of virus.