136. Genebanking of vegetatively propagated crops: Cryopreser- vation of 44 Mentha accessions. Elise R. Staats a , Leigh E. Towill a , Julie Laufmann a , Barbara M. Reed b , David E. Ellis a , a National Center for Genetic Resources Preservation, USDA- ARS, 80521 Fort Collins, CO, USA; b National Clonal Germ- plasm Repository, USDA-ARS, 97333-2521 Corvallis, OR, USA Many valuable crop genetic resources are vegetatively propa- gated and preservation of these resources is usually done in field plantings that are susceptible to countless biotic and abiotic risks. Cryopreserved shoot tips are one option to reduce risks of losing this valuable vegetatively propagated germplasm. A difficulty in cryopreservation of genetic resource collections is the large num- ber of genotypes involved. Mentha offers a good example of what could potentially be expected from a cryopreservation program of a given genus. Forty-six accessions from more than 20 Mentha species were included in this study. Forty-four accessions (96%) were successfully stored in liquid nitrogen (minimum 40% viabil- ity and 60 viable shoot tips in storage) at the National Center for Genetic Resources Preservation. Three methods were needed for the successful cryopreservation of these Mentha accessions. Ini- tially PVS2 vitrification without cold acclimation was used and was successful with 30 accessions (64%). The remaining acces- sions were cold acclimated prior to PVS2 vitrification and an additional 9 (20%) were successfully stored. Encapsulation–dehy- dration of the remaining accessions was successful for five addi- tional accessions (11%). Two accessions (4%) did not respond favorably to any of the cryopreservation methods tested. These results highlight the fact that diverse genotypes can be adapted to cryopreservation yet flexibility in the methods used is critical due to differential genotypic response. (Conflict of interest: None declared. Source of funding: USDA-ARS.) doi:10.1016/j.cryobiol.2006.10.137 137. Impact of summer conditions of growth (drought, defoliation) on freezing tolerance of trees. Magalie Poirier, Thierry Ameglio, Institut National de la Recherche Agronomique, U.M.R. 547 P.I.A.F. (INRA—Univ. Blaise Pascal), 63100 Clermont-Ferrand, France Low temperature represents one of the most important envi- ronmental constraints limiting the productivity and the distribu- tion of plants on the Earth. In temperate climate zones, plants undergo periodic transitions from a lower to a higher level of resistance. Temperature and light are thus the two main environ- mental factors controlling the development of cold hardiness in plants. Freezing is one of the severest stresses as it causes ice for- mation, dehydration and cell deformation. To withstand freezing, cold-hardy plants have developed various mechanisms to regulate the formation of ice in their tissues (supercooling, extraorgan and extratissue freezing) [J. Levitt (Ed.), Responses of Plants to Envi- ronmental Stresses, vol. 1, Chilling, freezing, and high tempera- ture stress, Physiological Ecology series, Academic Press, New York, 1980; A. Sakai, W. Larcher (Eds.), Frost survival of plants. Responses and adaptation to freezing stress. Ecological studies, Springer, Berlin, 1987]. Even if the freezing tolerance mechanisms are not well known yet, many studies showed the importance of carbohydrates in the acclimation process. For freezing tolerance, winter starch mobilization resulting in an increase in soluble sug- ars was an essential step on the way to cold hardiness. The effi- ciency of hardening may change with the summer conditions of growth. (e.g., late July defoliation). The aim of this study was to characterize the freezing tolerance and hardening status of dif- ferent tissues and organs in relation to their carbohydrate status as induced by contrasted summer conditions of growth (drought or defoliation). The first results indicate that these summer condi- tions have a strong effect on freezing tolerance of trees. The aerial organs (trunk and stem) were more resistant than the ground organs (tap root, big roots and thin roots). Between autumn and winter, cold hardiness of aerial organs was more important than ground organs. Finally, the relationship between soluble sugar concentrations and frost hardiness (LT50) of aerial organs showed a clear correlation (r 2 = 0.9) with the summer conditions of growth, contrary to the ground organs (r 2 < 0.25). (Conflict of interest: None declared. Source of funding: None declared.) doi:10.1016/j.cryobiol.2006.10.138 138. Desiccation sensitivity and cryopreservation of dehisched ginseng seeds. Ju-Won Yoon, Eun-Sun Hong, Haeng-Hoon Kim, Ho-Cheol Ko, Do-Yoon Hyun, Taesan Kim, Genetic Resources Division, National Institute of Agricultural Biotechnology, 441-707 Suwon, South Korea Ginseng, Panax ginseng, C.A. Meyer seeds have triple dor- mancy, i.e., immature embryo, hard seed and physiological dor- mancy. This study aims to establish systematic protocols of germination, desiccation and cryopreservation of dehisced Kore- an ginseng seeds for long-term conservation of ginseng germ- plasm. After-ripening of embryos was facilitated at 10 and 5 °C, while embryos were not germinated at 15 and 20 °C. Germi- nation of dehisced seeds at 10 and 5 °C following one day of treatment of benzyladenine or gibberellic acid facilitated germi- nation, though final germination at 120 days was not significantly different. Dehisced ginseng seeds were dried in the airflow of a laminar flow cabinet and in a seed drying room. The germination percentage of desiccated seeds decreased when the moisture con- tent (MC) was below 7.2%. High levels (more than 90%) of ger- mination after cryogenic exposure were obtained after drying in the vertical airflow of a laminar flow cabinet for 12–30 h (MC 10.6–7.2%). Decrease in the germination percentage of ginseng seeds due to desiccation damage and freezing injury was observed at a MC below 7.2% and above 12.1%, respectively. Therefore, the MC of ginseng seeds need to be controlled within the range of 8–11% to avoid damage from both desiccation and freezing. (Conflict of interest: None declared. Source of funding: None declared.) doi:10.1016/j.cryobiol.2006.10.139 139. Cryopreservation of grapevine (Vitis vinifera L) embryogenic callus by vitrification. M. Elena Gonza ´lez-Benito a , David Campos a , Jose ´ R. Vidal b , a Universidad Polite ´cnica de Madrid, Dept. Biologı ´a Vegetal, 28040 Madrid, Spain; b Universidad Polite ´cnica de Madrid, Dept. Biotecnologı ´a, 28040 Madrid, Spain Grapevine is one of the most economically important fruit crops worldwide. Biotechnology techniques are being developed for the genetic improvement of grapevine, especially genetic transformation. Grapevine embryogenic cell suspensions have Abstracts / Cryobiology 53 (2006) 367–446 425