Employment of encapsulation-dehydration method for liquid nitrogen cryopreservation of ornamental plant explants propagated in vitro

In the present studies, an attempt has been made to develop a method of liquid nitrogen preservation of plant explants propagated in vitro in the laboratory of the Department of Ornamental Plants, of Agricultural University in Kraków: shoot apical and axillary meristems of Rosa ‘New Dawn’, somatic embryos of snowdrops Galanthus nivalis L. and G. elwesii Hook, and gametophyte of Phlebodium aureum (L.) J. Sm. (golden polypody). After encapsulation of plant material, it was dehydrated by quick method (capsules were placed in liquid media containing 0.75 M sucrose for 18 h) or by gradual method (capsules were transferred to liquid solutions of media with increasing sucrose concentrations from 0.3 M to 1 M for consecutive 7 days). Moreover, some explants for cryopreservation were treated with the medium containing elevated sucrose level (0.25 M) for 8 weeks. Cryopreservation of ornamental plants 62 The obtained results indicate that survival rate of plant tissue after freezing in liquid nitrogen depended on plant material: apical meristems of roses regenerated callus but axillary meristems did not survive the freezing, gametophyte of golden polypody regenerated multiplying gametophytes, somatic embryos of snowdrops, although did not change appearance (did not blacken), did not regenerate. Cutting capsules after freezing did not influence regeneration of the cryopreserved plant explants. It was shown that employment of slow dehydration method for preparation of plant material for cryopreservation allowed to obtain a viable callus tissue of Rosa ‘New Dawn’ and propagating Phlebodium aureum gametophytes. Rose axillary buds and golden polypody gametophytes prepared for cryopreservation by fast dehydration method did not survive freezing.