title: Comparison of cryopreservation techniques for long-term storage of ash (Fraxinus excelsior L.).
abstract: The main purpose of this study was to develop a cryopreservation protocol for ash and to highlight the importance of testing different clones and plant material of different ontogenetic states. In vitro-grown ash (Fraxinus excelsior L.) shoot tips were successfully cryopreserved following optimization of the PVS2-vitrification protocol. Pretreatment conditions were optimized and three cryopreservation techniques (encapsulation/dehydration, PVS2-vitrification and encapsulation-vitrification) were tested one after another. PVS2-vitrification proved to be the most suitable technique. In vitro-grown shoot tips of ash were successfully cryopreserved with a mean regrowth of 73% for juvenile clones and 67% for selected mature trees. The optimum preculture conditions and the initial protocol were: 10 days cold hardening, preculture for 2 days on medium with 0.8 M glycerol, incubation in 2 M glycerol solution for 20 min at 22 degrees C followed by PVS2 for 25 min at 0 degrees C on ice and direct immersion in liquid nitrogen. Warming was carried out in 43 degree C water for 1 min followed by 22 degree C water for 10 sec. The encapsulation/dehydration method was not successful for shoot tips of F. excelsior because the shoots were sensitive to osmotic dehydration. The encapsulation/vitrification method resulted in a mean regrowth of only 16%. PVS2 vitrification can now be used to store important ash germplasm of either juvenile or mature trees.
authors.affiliation: Lower Saxony Forest Research Institute, Department of Forest Genetic Resources, Staufenberg, Germany. Katja.schoenweiss@gmx.de
authors.forename: Katja
authors.initials: K
authors.lastname: Schoenweiss
authors.forename: Andreas
authors.initials: A
authors.lastname: Meier-Dinkel
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Grotha
mesh_terms: D015925:Cryopreservation / Q000379:methods*; D003470:Culture Media; D031661:Fraxinus; D006801:Humans; D018520:Plant Shoots; D014022:Tissue Survival
chemical_list: D003470:Culture Media