Efficient Breeding and Cultivation of Type 2 Red-fleshed Apple Cultivars Using a Search System for Suitable Apple Cultivar Combination

As apple possesses self-incompatibility, knowledge of the S-genotypes is very important for apple breeding and cultivation. We investigated the S-RNase genotypes of 13 type 2 red-fleshed apple cultivars and 8 lineages. All of the investigated type 2 red-fleshed apples contained the S3-RNase allele closely linked to the red-fleshed trait. We made a search system for ovule parents to efficiently produce new type 2 red-fleshed cultivars based on the S-RNase allele information (http://www.agr.nagoya-u.ac.jp/∼hort/apple/red/). More than 90% of progenies from crossing a selected white-fleshed ovule parent with a type 2 red-fleshed pollen parent are expected to show the red-fleshed phenotype. We also compiled a database of the S-RNase genotypes of more than 1 000 apple cultivars, including a survey system of cultivar combinations showing those that were fully incompatible, semicompatible and fully compatible, written in Chinese (http://www.agr.nagoya-u.ac.jp/∼hort/apple/ch/) and Japanese (http://www.agr.nagoya-u.ac.jp/∼hort/apple/ja/). Keywords: Malus × domestica, type 2 red-fleshed, S-RNase, genotype, cultivar combination, self-incompatibilit