Skip to main content
ARS Home » Pacific West Area » Corvallis, Oregon » National Clonal Germplasm Repository » Research » Publications at this Location » Publication #167211
Title: IN-VITRO STORAGE AND CRYOPRESERVATION OF HOPS (HUMULUS L.) GERMPLASM

Author
item Reed, Barbara

Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2004
Publication Date: 2/1/2005
Citation: Reed, B.M. 2005. In-vitro storage and cryopreservation of hops (humulus l.) germplasm. Acta Horticulturae. 668:249-256.

Interpretive Summary: The National Clonal Germplasm Repository (NCGR) stores the US collection of hops. Hops are usually stored as trellised plants in field collections. These plants are susceptible to loss from environmental stresses and insect or disease attacks. To insure the safety of the collection, a subset of the field collection was established as virus-free tissue cultures stored at refrigerator temperatures and also grown in pots in screened houses. Medium-term storage of in vitro cultures keeps plants available for distribution. We found that 70 different types of hops plants could be stored at refrigerator temperatures (45 °F) for an average of 14 months and a range of 6 to 26 months. Long-term (100 year) storage of the collection as tiny shoot tips frozen in liquid nitrogen (-320 °F) will provide additional security. We tested and stored 100 meristems of each plant type. Shoot tips were grown on special growth medium, and antifreeze solutions were added for additional protection. Shoot tips were slowly frozen to -40 °F, immersed in liquid nitrogen, and stored. Recovery ranged from 30 to 80%.

Technical Abstract: The USDA-ARS National Clonal Germplasm Repository (NCGR) stores the global diversity of Humulus for the US Plant Germplasm System as trellised plants in a field genebank. In-vitro storage and cryopreservation are considered excellent ways to provide medium and long-term storage for plant collections. In this study we characterized the response of diverse Humulus genotypes to in vitro storage under low light at 4 °C and cryopreservation in liquid nitrogen by slow cooling. Plantlets were cold acclimated, stored in plastic tissue-culture bags, and evaluated at 4 month intervals. The average storage time without transfer for the 70 genotypes evaluated was 14 + 3.5 months with a range of 6 to 26 months. Plantlets for cryopreservation were cold acclimated for 2 weeks, pretreated for 48 hr and cooled to -40 °C at 1 °C per minute, and plunged into liquid nitrogen. Mean recovery of cryopreserved shoot tips was 54% + 13 with 2-wk cold acclimation. A few genotypes required longer cold acclimation for good recovery following liquid nitrogen exposure.