F1 hybrid of cultivated apple (Malus 3 domestica) and European pear (Pyrus communis) with fertile F2 offspring

The establishment of intergeneric hybrids for horticultural and agricultural crops is still a demanding task for breeding programmes. The aim of such approaches is to introduce new quality and resistance traits and to enlarge the gene pool. Recently, an F1 hybrid between Malus × domestica and Pyrus communis became available which arose from a breeding approach undertaken in the late 1980s by the breeder Max Zwintzscher (Cologne-Vogelsang). Unlike previous reports, viable and fertile F2 plants were obtained from this F1 hybrid line by author HS, providing a unique perspective not only for genomic, transcriptomic and metabolomic studies but also for advanced breeding strategies. Here, we give the first report on the confirmation and characterization of the F1 hybrid by phenotypic, genetic and biochemical means. The intergeneric hybrid shows an intermediary phenotype of leaves, flowers and fruits, and some disorder of secondary shoot growth. Nuclear DNA content is also intermediary and corresponds to a diploid state. Apple and pear type rDNA as well as SI alleles from each genus were found. At the metabolic level, parallel biosynthesis of the apple dihydrochalcone phloridzin and of arbutin, a p-hydroquinone-glucoside typical for pear, take place leading to considerable concentrations of both in leaves. The overall data allow secure confirmation of the hybrid character and give a first insight into the hybrids genetics and physiology