Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 24, 2004
Publication Date: February 1, 2005
Citation: Hummer, K.E. 2005. Wild humulus genetic resources at the u.s. national clonal germplasm repository. Acta Horticulturae. 668:75-80. Interpretive Summary: The hop collection at the U. S. Department of Agriculture (USDA), Agricultural Research Service (ARS), National Clonal Germplasm Repository (NCGR) in Corvallis, Oregon, has been increasing. Over the past 23 years more than 10 plant collecting trips have obtained wild species representatives for the collection. Some of these trips were privately sponsored. Others were publicly supported through U. S. Department of Agriculture Plant Exploration grants for foreign and domestic expeditions. Wild hop seed was collected from more than seven European and Asian countries, two Canadian provinces, and twelve states. More than 199 seedlots or plants are preserved at the NCGR from these expeditions. The origins of the plant material can be searched through the web at the Germplasm Resources Information Network (GRIN) database. Seeds from the expeditions are stored in a freezer at the NCGR. Plants are kept in a screenhouse and tested for viruses and other diseases. The plants are also stored as tissue cultured plants. Tiny growing points are stored in liquid nitrogen for decades of storage. Plants or seeds are available for distribution for researchers from the NCGR collections.
Technical Abstract: During the past 23 years the Humulus genetic resource collection at the U. S. Department of Agriculture (USDA), Agricultural Research Service (ARS), National Clonal Germplasm Repository (NCGR) in Corvallis, Oregon, has greatly benefited from many international plant collecting trips. Significant contributions from North America include several privately sponsored expeditions to Manitoba, Saskatchewan, Iowa, Kentucky, Minnesota, Missouri, Montana, Nebraska, New York, North Dakota, and Wisconsin, and others sponsored by the USDA to Colorado, New Mexico, and Arizona. In addition, USDA-sponsored foreign expeditions to Albania, Armenia, China, Georgia, Kazakhstan, and Russia, have also expanded the representation of global Humulus diversity. More than 199 wild hop accessions are preserved at the NCGR from these expeditions. Locality information from the plant collecting expeditions is loaded to the publicly accessible Germplasm Resource Information Network (GRIN) database. Seed from these accessions are inventoried, labeled, and stored at -20 C. Germination protocols are being reviewed and revised. Seedlings from these accessions are being evaluated for disease resistance, morphological traits and chemical and genetic profiles. Genotypes with specific quality traits are being preserved as plants growing in screened enclosures, protected from virus or other pathogen infection. Specific genotypes are cultured in vitro. These tissue cultures are preserved at 4 C for up to 2 years. Meristems from tissue cultures are cryopreserved and stored at a remote location for long-term, back-up preservation. Plant propagules including stem cuttings, rhizomes, tissue cultures, or seeds, are available for distribution to international researchers upon request.