ARS | Publication request: Distribution of Four Viruses in Single and Mixed Infections Within Infected Watermelon Plants in Florida

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 23, 2010
Publication Date: November 1, 2010
Citation: Turechek, W., Kousik, C.S., Adkins, S.T. 2010. Distribution of Four Viruses in Single and Mixed Infections Within Infected Watermelon Plants in Florida. Phytopathology. 100:1194-1203.

Interpretive Summary: The whitefly-transmitted viruses Squash vein yellowing virus (SqVYV), Cucurbit leaf crumple virus (CuLCrV) and Cucurbit yellow stunitng disorder (CYSDV), and to a lesser extent, the aphid transmitted virus Papay ringspot virus type W (PRSV-W) have had serious impact on watermelon production in west-central and southwest Florida in recent years. To determine virus distribution within plants, we collected 80 entire plants randomly, 20 each on four different dates, from a commercial watermelon field showing symptoms of SqVYV, CuLCrV and PRSV-W, and possibly CYSDV. This was followed by a smaller sampling of five plants in a different commercial planting. Results showed that the distribution of SqVYV in vines decreased proportionately with distance from the crown compared to CuLCrV which tended to be more evenly distributed throughout the plant. The distribution of PRSV-W resembled that of SqVYV, but with a slightly greater probability of detection at the tip of the vine. Similar trends were detected in the smaller sampling; however, CYSDV was also detected in these plants. Overall, our results indicate that SqVYV, CuLCrV, and PRSV-W are distributed differently in watermelon plants, and this difference has implications for sample collection, and may affect vector acquisition and transmission of these viruses.

Technical Abstract: Whitefly-transmitted Squash vein yellowing virus (SqVYV) and Cucurbit leaf crumple virus (CuLCrV), and aphid-transmitted Papaya ringspot virus type W (PRSV-W) have had serious impact on watermelon production in southwest and west-central Florida in recent years. Tissue blot nucleic acid hybridization assays were developed for simple, high throughput detection of these three viruses as well as the more recently introduced Cucurbit yellow stunting disorder virus (CYSDV). To determine virus distribution within plants, we collected 80 entire plants randomly, 20 each on four different dates, from a commercial watermelon field showing symptoms of SqVYV, CuLCrV and PRSV-W, and possibly CYSDV. This was followed by a smaller sampling of five plants in a different commercial planting. Tissue prints were made from cross sections of watermelon plants from the crowns through the tips at 0.6 m intervals on nylon membranes and nucleic acid hybridization assays were used for virus detection. Results from testing of crown tissue showed that SqVYV, CuLCrV and PRSV-W were present in approximately 37%, 43.5% and 54%, respectively, of the 80 plants from the first field. For individual vines diagnosed with SqVYV, the distribution of SqVYV in vine tissue decreased proportionately with distance from the crown. The probability of detecting SqVYV was 70% at the base of the vine, compared to 23% at the tip of the vine, In contrast, CuLCrV tended to be more evenly distributed throughout the plant with a slightly higher probability of detection at the growing tip. The distribution of PRSV-W resembled that of SqVYV, but with a slightly greater probability of detection at the tip of the vine. Similar trends were detected in the smaller sampling; however, CYSDV was also detected in these plants. Overall, our results indicate that SqVYV, CuLCrV, and PRSV-W are distributed differently in watermelon plants, and this difference has implications for sample collection, and may affect vector acquisition and transmission of these viruses.