The genetic control of resistance of the non-commercial watermelon accession PI 595201 to the Watermelon mosaic virus (WMV) was studied. Parental lines Crimson Sweet (P1 - susceptible parent) and PI 595201 (P2 - resistant parent), generations F1, F2 and backcrosses to both parents were tested. Symptom severity after mechanical inoculation with WMV was rated on a scale from 1 (no symptoms) to 5 (intense mosaic and foliar distortion). Crimson Sweet had a mean value of 4.0, whereas PI 595201 had a mean value of 1.0, demonstrating the contrasting reaction of these lines for WMV resistance. The heritability estimates were > 0.8, indicating that genetic gains from selection are feasible. The additive-dominance model was suggested to explain resistance inheritance. The hypothesis of monogenic control of WMV resistance in watermelon was rejected with an indication that the resistance of PI 595201 is under oligo or polygenic control, possibly by complete dominance in the direction of higher levels of resistance. The estimated number of genes that control WMV resistance was 4.16.
genetic control; Cucurbitaceae; heritability; oligogenes; Potyvirus
