Inheritance of tomato leaf resistance to Phytophthora infestans - new information based on laboratory tests on seedlings

Inheritance of tomato resistance to P. infestans was studied in progenies of crosses of resistant accessions: West Virginia 700, Ottawa 30, PI224675 and the variety New Yorker and also of the variety West Virginia’63 and resistant breeding lines crossed with susceptible forms. Populations of F1, F2, parents and resistant standards were evaluated for resistance to late blight using the test on seedlings grown in liquid medium. Resistance of the accessions West Virginia 700, Ottawa 30 and PI224675 was found to be identical and determined by the same genes: Ph-1 and Ph-2. It has not been recognized if these accessions carry other genes, neither if the variety West Virginia’63 and lines of equal resistance possess other genes beside Ph-2.