Linkage of Turnip Mosaic Virus Susceptibility and Downy Mildew, Bremia lactucae, Resistance in Lettuce1

Abstract

Abstract Data for resistance in Lactuca sativa L. to turnip mosaic virus (TuMV) and downy mildew were obtained from 8 F 2 progenies of crosses between TuMV-susceptible, mildew-resistant, and TuMV-resistant, mildew-susceptible parents. The F 1 progeny were TuMV and mildew resistant. Of 3,682 F 2 plants assayed 2,773 were TuMV resistant and 909 TuMV susceptible. A total of 2,788 mildew-resistant plants were observed, and 904 mildew susceptible. Resistance to TuMV and mildew are each controlled by a single dominant gene, designated herein as Tu and Dm . The TuMV-susceptible gene, tu , is linked with the mildew-resistant gene, Dm . In the repulsion phase, the cross-over value was 12.5% ± 1.6.