Apple Genetic Resources: Diversity and Conservation

Diverse apple cultivars and wild Malus species offer necessary allelic diversity to breeding and research programs. Wild apple species are found in native landscapes of countries throughout the Northern Hemisphere; however, some of these species are at risk of being lost, particularly if trees are unable to thrive under changing climatic conditions, disease/pathogen outbreaks, and human encroachment. Apple genebanks have been established to ensure that user communities have current and future access to these genetic resources. Herein, we describe necessary components of apple genebanks, including collection maintenance forms (trees in orchards, in vitro cultures, low-temperature medium-term storage, and cryopreservation), acquisition of genebank accessions, documentation and data management, distribution of collection materials, as well as characterization and evaluation (phenotypic evaluations and genetic tools for collection management). We conclude with a summary of international apple genebank holdings and provide some examples of how collaborations among genebanks would benefit the global community.