INHERITANCE OF RESISTANCE TO THE WATERMELON STRAIN OF PAPAYA RINGSPOTVIRUS IN THE CUCUMBER LINE TMG-1

The inbred cucumber (Cucumis sativus L.) line TMG-1 is resistant to th ree potyviruses: zucchini yellow mosaic virus (ZYMV), watermelon mosai c virus (WMV), and the watermelon strain of papaya ringspot virus (PRS V-W). In this study we sought to determine the genetics of resistance to PRSV-W. TMG-1 was crossed with WI-2757, an inbred line susceptible to all three viruses, Segregation data indicated that resistance to PR SV-W was due to a single dominant gene (proposed designation, Prsv-2). Enzyme-linked immunosorbent assay (ELISA) data suggested that the mec hanism of resistance to PRSV-W differs from that for ZYMV and WMV, and may be better described as tolerance. Although the plants were free o f symptoms, high PRSV-W titers existed in young expanding leaves of th e TMG-1 plants and the WI-2757 x TMG-1 F-1 progeny.