USDA Apple (Malus) Collection
The domesticated apple, Malus domestica, easily wins in a popularity contest. Unlike most other fresh produce, apples are marketed by name and many consumers are familiar with several cultivars. As one of the world’s largest and most diverse apple collections, the PGRU apple collection is the center piece of the PGRU clonal repository. PGRU maintains 6,079 unique accessions, representing 55 species and cultivated hybrids, including 2,937 permanent accessions, research populations, seedlings under evaluation, and seed lots. Apples and wild apple relatives are largely self-incompatible and can hybridize between species, creating a tremendous reservoir of genetic diversity. Despite the diversity of apple genetic resources, analysis suggests that modern apple breeding narrowly relied on a limited number of founding parents (Noiton and Alspach 1996). M. domestica is primarily an interspecific hybrid between progenitor species Malus sieversii and the European crabapple, Malus sylvestris (Velasco et al. 2010; Cornille et al. 2012). Additional species contributed also to apple domestication and more modern breeding included further hybridization to bring key traits from wild relatives into a domesticated background (Brown 2012). As such, in situ and ex situ preservation of wild Malus are a critical focus (Bramel and Volk 2019). Loss of habitat and gene flow of M. domestica into wild Malus populations are concerning (Cornille et al. 2013).
From 1989 to 1996, PGRU led explorations for wild Malus in Central Asia, of which the collection of M. sieversii from Kazakhstan was a crowning achievement (Forsline et al. 2003). Resistance for fire blight, apple scab, and blue mold were identified in among these resources (Forsline and Aldwinckle 2004; Norelli et al. 2017). More recently, PGRU has been active to conserve wild germplasm of Malus angustifolia, Malus coronaria, and Malus ioensis from North America, and Malus doumeri from Vietnam.
Excerpt from: Gutierrez B, Battaglia K, Zhong G-Y (2020) Preserving the future with the USDA Plant Genetic Resources Unit tart cherry, grape, and apple germplasm collections. Journal of the American Pomological Society 7
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Visit the APPLE crop page in GRIN-Global to find citations, descriptor data, and genetic markers.
Interested in plant conservation? Read about the vulnerability of apple genetic resources.
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Apple Production in the United States
Data from USDA NASS
PGRU Apple Accession Distribution 1988-2019
Data from GRIN-Global