Infection of soybean by cucumber mosaic virus as determined by viral movement protein.

To characterize the host range determinant of the soybean strain of Cucumber mosaic virus (CMV) we analyzed a series of pseudorecombinants and chimeric viruses between infectious transcripts from two soybean strains (CMV-SC and CMV-SD) and an ordinary strain (CMV-Y). CMV-Y could not infect soybeans, even locally. Systemic infection of the two soybean-adapted soybean isolates on soybean plants mapped to RNA3. Chimeric RNA3s from between CMV-SC and CMV-Y, and chimeric RNA3s from between CMV-SC and CMV-SD, were made and inoculated onto wild soybean Iwate and soybean cv. Tsurunoko. The 3a region determined the viral systemic movement in the plants. In the wild soybean ecotype Hyougo, cell-to-cell movement of two different CMV soybean strains, one of which infects systemically while the other does not, in the inoculated leaves were almost the same, suggesting that the resistance of soybean operates at the level of long-distance movement. Our results clearly suggest that movement protein is a host determinant of CMV soybean strains.