title: Genes determining leucine aminopeptidase and mildew resistance from the ornamental apple, 'White Angel'.
abstract: Mildew resistance in the ornamental apple 'White Angel' was found to be determined by complementary genes. The gene R w was found to be necessary for the expression of resistance controlled by the resistance gene Pl w . The close linkage between the isoenzyme gene, Lap-2, for leucine aminopeptidase and P1 w was confirmed. The efficiency of Lap-2 as a marker in screening for mildew resistance is limited, as it cannot account for susceptible plants with the r w r w P1 w p1 w genotype. It has, however, an important role to play in combining resistance genes from different sources. The genotypes of 'White Angel' (R w r w , Pl w pl w , Lap-2an), 'Jester' (R w r w , p1 w p w , Lap-2an) 'Katja' (R w r w ,p1 w p1 w , Lap-2an) and 'Gloster 69' (r w r w , p1 w p1 w , Lap-2an) were determined. It also appeared that R w might influence Lap-2 activity in young seedlings.
authors.affiliation: Horticulture Research International, East Malling, West Malling, ME19 6BJ, Kent, UK.
authors.forename: I
authors.initials: I
authors.lastname: Batlle
authors.forename: F H
authors.initials: FH
authors.lastname: Alston