AFLP and S-gene analysis in apple cultivars and in their putatively homozygous offspring

By pollination with irradiated pollen grains, female gametes in apple are induced to develop into embryos. Following germination of the immature embryos in vitro, shoots are produced that are putatively homozygous. To prove the homozygous nature of these shoots, we are developing evaluation tools at different stages: 1. visual observation of the expression of leaf anthocyanins, derived from the pollen parent; 2. PCR analysis of the allelic constitution at the highly polymorphic S-locus; and 3. AFLP analysis at several independent loci. In this paper, we describe the development of the latter two DNA-based assays and their application to progeny derived from two crosses between apple cultivars.