Inheritance of Resistance to Downy Mildew in a Gynoecious Muskmelon. David Kenigsbuch, Graduate Student, Department of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel 52100. Yigal Cohen, Professor, Department of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel 52100. Plant Dis. 73:994-996. Accepted for publication 28 April 1989. Copyright 1989 The American Phytopathological Society. DOI: 10.1094/PD-73-0994.

The gynoecious, downy mildew-susceptible Cucumis melo WI998 was stabilized for gynoecity and crossed with C. melo PI 124111F, a monoecious breeding line resistant to pathotype 3 of Pseudoperonospora cubensis. F₁ plants (all monoecious) were moderately resistant to downy mildew (reaction types 22 and 23). F₂ plants (1/16 gynoecious) segregated 1 susceptible (reaction type 11):14 moderately resistant (reaction types 12, 13, 22, 23, 24, and 33):1 resistant (reaction types 33 and 34). The backcross progeny of F₁ to the susceptible parent (WI998) segregated 3 susceptible:1 moderately resistant. The backcross progeny to the resistant parent (PI 124111F) segregated 3 moderately resistant:1 resistant. The data support a digenic partially dominant inheritance of resistance against pathotype 3 of P. cubensis.

Keyword(s): Cucurbitaceae, genetics, germ plasm, resistance genes.