Twenty advanced watermelon breeding lines, derived from the cross between cv. Crimson Sweet (susceptible) and PI 595201 (resistant to WMV and PRSV-W), were screened for resistance to both potyviruses. The twenty lines, among with Crimson Sweet and PI 595201, were inoculated with either WMV or PRSV-W, in two different greenhouse trials. Plants were evaluated for symptoms 35 and 49 days after the first inoculation (DAI), using a scale from 1 (no symptoms) to 5 (severe mosaic and foliar distortion). Evaluations at 35 DAI indicated that lines 1, 2 and 20 had good levels of resistance to both WMV and PRSV-W, with ratings of 1,95, 1,80 and 2,25 for WMV, and of 2,50, 2,30 and 2,50 for PRSV-W, respectively. Lines 5, 7 and 13 were resistant to WMV only, whereas lines 3, 10 and 18 were resistant to PRSV-W only. The reaction of the lines 49 DAI remained essentially unchanged. The existence of lines with resistance to WMV only and to PRSV-W only, along with lines with resistance to both viruses, indicates that resistance to WMV and PRSV-W are under control of different genes.
Cucurbitaceae; genetic control; Potyvirus
