WILD HUMULUS GENETIC RESOURCES AT THE U.S. NATIONAL CLONAL GERMPLASM REPOSITORY

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 private and USDA sponsored expeditions to Arizona, Colorado, Iowa, Kentucky, Manitoba, Minnesota, Missouri, Montana, Nebraska, New Mexico, New York, North Dakota, Saskatchewan, and Wisconsin. In addition, USDA-sponsored foreign expeditions to Albania, Armenia, China, 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 o 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.