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United States Department of Agriculture

Agricultural Research Service

Title: Medium and Long-Term Storage of Rubus Germplasm

Authors
item Reed, Barbara
item Hummer, Kim

Submitted to: Acta Horticulture Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: December 7, 2005
Publication Date: December 20, 2005
Citation: Reed, B.M., Hummer, K.E. 2005. Medium and long-term storage of rubus germplasm. Acta Horticulture Proceedings. Paper No. 10. p.17.

Interpretive Summary: More than seven hundred blackberry and raspberry cultivars and species are held in the collections of the USDA-ARS National Clonal Germplasm Repository at Corvallis. The main collections are potted plants in screenhouses with tissue cultures as a secondary backup and cryopreservation (storage in liquid nitrogen) as the long-term storage option. The tissue culture collection includes about 200 accessions. In vitro cold storage of these accessions is at refrigerator temperatures with 12 h of low light. Storage facilities for tissue culture collections vary, however 45° F storage in the dark or with a low light appears to be acceptable for most raspberry and blackberry types if they are evaluated on a regular basis and moved to room temperature when they decline in health. Cold sensitive and tropical genotypes which typically survive only a short time in cold storage can be stored at room temperature on a special medium. The shoot tips of cold-acclimated cultivars and species of Rubus (blackberry and raspberry) can be successfully stored in liquid nitrogen. Cold acclimation (CA) treatment improved the recovery of shoot tips cryopreserved by the slow freezing method. Regrowth was greatly improved by increasing the length of CA before freezing. Shoot growth was also increased by modifying the shoot recovery medium. A protocol for cryopreservation of Rubus germplasm should include a CA period of 6-10 weeks and recovery on a modified medium.

Technical Abstract: More than seven hundred Rubus cultivars and species are held in the clonal collections of the USDA-ARS National Clonal Germplasm Repository at Corvallis. The main collections are potted plants in screenhouses with in vitro culture as a secondary backup and cryopreservation in progress for some accessions. The in vitro collection includes about 200 accessions. In vitro cold storage of these accessions is at 4°C with 12 h of low light. Plantlets are cold acclimated for one week before storage. Storage facilities for germplasm collections vary, however 4° C storage in the dark or with a photoperiod appears to be acceptable for most Rubus germplasm if quarterly inventories are used to evaluate materials and remove those at risk. A reduced-nitrogen medium extends room temperature storage to nine months as a useful alternative for cold sensitive and tropical genotypes which typically survive only a short time in cold storage. The meristems of cold-acclimated cultivars and species of Rubus (blackberry and raspberry) were successfully cryopreserved through optimization of cryoprotectants, cooling rates and cold acclimation treatments. Alternating low temperature treatment as a cold acclimation (CA) treatment improved the recovery of shoot tips cryopreserved by the slow freezing method. The length of the CA required varied from 1 to 10 weeks depending on the genotype. Frozen-thawed Rubus shoot tips directly produced shoots from either apical meristems or axillary buds but not from callus. The histological evidence indicated the safety of using meristems for Rubus germplasm storage. Shoot formation was greatly improved by increasing the duration of CA before freezing. Shoot formation was also increased and callus formation decreased by eliminating IBA from the shoot recovery medium. A protocol for cryopreservation of Rubus germplasm should include a CA period of 6-10 weeks and recovery on medium without auxin.

Last Modified: 8/29/2014
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