Malus germplasm in Germany: collection, conservation and evaluation

In Germany, all activities regarding fruit genetic resources management are based at the German National Program for Genetic Resources of Agricultural and Horticultural Plants. In the Fruit Genebank of the Julius Kühn-Institut, Institute of Breeding Research on Fruit Crops, Malus is the most prominent collection, consisting of 816 cultivars and 572 wild species accessions. The Malus accessions were expanded substantially through expeditions to the centres of origin. Field trips were undertaken to the Caucasus, where 1,167 seedlings of Malus orientalis originating from 247 accessions were collected and are now available for extensive phenotypic and molecular evaluation. Since fruit species are mainly vegetatively propagated crops, they need to be maintained in field collections, which is expensive. Duplication of genebank collections is necessary to prevent complete loss of genetic resources due to climate change, biotic and abiotic disasters and can be any useful combination of field plantings at locations other than the main collection, in vitro culture or cryopreservation. The 575 cultivars selected for the decentralized network of the German Fruit Genebank are to be duplicated at a second site as field collection within this network; 88% are realized. The Malus wild species accessions are held exclusively at the Fruit Genebank in Dresden-Pillnitz. Twenty-nine percent of these accessions have been duplicated by means of cryopreservation using the dormant bud method. Germplasm collections are valued for their diversity and their availability. Based on results obtained from several comprehensive characterisation and evaluation projects, the importance of these genetic resources in breeding research and for future apple breeding programmes is clear. All points are significant contributions to the National Program for Genetic Resources of Agricultural and Horticultural Crops in Germany and so contribute to the realisation of a global strategy for Malus. This paper provides a review of the current status of ex situ conservation of Malus in Germany at the German Fruit Genebank.