INHERITANCE OF RESISTANCE TO THE MOROCCAN WATERMELON MOSAIC-VIRUS IN THE CUCUMBER LINE TMG-1 AND COSEGREGATION WITH ZUCCHINI YELLOW MOSAIC-VIRUS RESISTANCE

Inbred lines derived from the Chinese cucumber (Cucumis sativus L.) cu ltivar, 'Taichung Mou Gua' (TMG), have been shown to be resistant to s everal potyviruses including: zucchini yellow mosaic virus (ZYMV), zuc chini yellow fleck virus (ZYFV), watermelon mosaic virus (WMV) and the watermelon strain of papaya ringspot virus (PRSV-W). Recently, an add itional virus that infects cucurbits, the Moroccan watermelon mosaic v irus (MWMV), has been determined to be a distinct member of the potyvi rus group. This study demonstrates that TMG-1 possesses resistance to MWMV. Rub or aphid inoculated TMG-1 seedlings remain free of symptoms. Progeny analyses of the F-1, F-2 and backcross generations show that resistance to MWMV is conferred by a single recessive gene (proposed d esignation, mwm). Sequential inoculation of progeny possessing resista nce to ZYMV followed by MWMV (or MWMV followed by ZYMV) and analysis o f F-3 families derived from F-2 individuals selected for resistance to ZYMV indicate that both resistances are conferred by the same gene, o r two tightly linked genes.