Procedures for collection, conservation, evaluation and documentation of Malus germplasm

The Plant Genetic Resources Unit in Geneva (PGRU) New York, U.S.A., is part of the National Plant Germplasm System (NPGS), administered by the United States Department of Agriculture (USDA), Agricultural Research Service (ARS). Malus is the most extensive PGRU collection and consists of 3739 accessions. The majority of these accessions (2438) are clonally-propagated and stored as duplicate orchard trees. Dormant buds of 1503 accessions are stored in a back-up collection in liquid nitrogen at the National Seed Storage Laboratory (NSSL) in Fort Collins, Colorado, U.S.A. Since 1988, 1301 accessions of wild Malus spp. from centers of origin throughout the world are preserved as seed lots. The majority of these were collected from the primary gene pool (Malus sieversii, Lebed.) in Central Asia from 12 distinct habitats and 892 tree sources. Collaborative evaluation for disease resistance and horticultural and molecular characterization is being conducted on 25,000 of these seedlings in 24 worldwide laboratories. A core subset has been established including 208 clones. This is a test-array of the most genetically-diverse accessions available for evaluation of specific genetic traits. About 3000 accessions are distributed annually. Accession history, characterization, and evaluation are documented in the Germplasm Resources Information Network (GRIN). The core subset and 40% of the remainder of the collection has been characterized with 25 morphological descriptors. Information on the Malus collection and other commodities in the NPGS can be accessed: http://www.ars-grin.gov/npgs/.