1986 Volume 52 Issue 1 Pages 22-30
Cucumber mosaic virus (CMV) and zucchini yellow mosaic virus (ZYMV) simultaneously inoculated on cucumber plants caused severer symptoms than those produced by CMV single infection, whilst weakened the symptoms caused by ZYMV. Determination of CMV concentration by infectivity assay indicated that concentration of CMV in doubly infected plants was higher than those in singly infected plants. On the contrary, ZYMV concentration significantly decreased after mixed infection as determined by enzyme-linked immunosorbent assay. Yields of CMV obtained by sucrose density gradient centrifugation from doubly infected cucumber plants were distinctly higher than those from singly infected ones about 3 weeks after inoculation. The enhanced multiplication of CMV was also found in doubly infected plants whether CMV was inoculated 1 or 2 weeks before or after ZYMV inoculation. Electron microscopy of doubly infected leaf cells revealed abundant masses of CMV aggregates in the cytoplasm. Examination of CMV infected protoplasts prepared from singly and doubly infected cucumber leaves suggested that higher concentration of CMV in double infection was due not only to the increase of CMV quantity in individual cells, but also to the increase in proportion of CMV infected cells.