Breeding for Resistance to Verticillium dahliae Race 2 of Tomato in North Carolina1

Abstract

Abstract Parental, F1, F2, and backcross generations of tomato (Lycopersicon esculentum Mill.) lines Morden MEL2668170G (MEL) and ‘Walter’ (WA) were screened as seedlings for resistance to verticillium wilt (Verticillium dahliae Kleb.) race 2. Disease reaction means, based on the number of leaves and cotyledons with symptoms 5.5 weeks after inoculation, were 2.7 for MEL and 4.6 for WA. Resistance in MEL appeared to be recessive with narrow sense heritability estimated at 0.25 or less. Disease severity was sometimes inadequate to avoid the selection of escapes in advanced generations. Analysis of F3 progenies, however, indicated 3 genes or less might be involved. Results suggest race-2 resistance can be maintained in advanced generations by the elimination of highly susceptible plants and by progeny testing to insure recovery of the most resistant individuals rather than escapes.