Cryopreservation of Armoracia rusticana P. Gaert., B. Mey. et Scherb. (Horseradish) Hairy Root Cultures

Abstract

Cryopreservation has become important as a means of ensuring the long-term preservation of plant germplasm. It is particularly useful for the conservation of precious and rare species on the verge of extinction due to global environmental problems. In the case of higher plants, roots are considered to be appropriate material for cryopreservation since many uniform root samples can be taken from such plants growing in the field without inflicting lethal damage. In vitro transformed hairy root culture is a very useful model material for investigating cryopreservation of roots because of the high levels of uniformity of their morphology and rapid growth. Their property of high plantlet regeneration frequency allows clonal propagation of elite plants. Furthermore, hairy root cultures have been shown to be very useful material for the production of valuable secondary metabolites. Therefore, cryopreservation of hairy root cultures is also important to establish safe patent repositories of lines capable of producing products of commercial interest. However, there are only a few reports in the literature on the cryopreservation of root cultures by conventional slow-freezing (Benson and Hamil 1991; Bajaj 1995; Teoh et al. 1996) or vitrification (Yoshimatsu et al. 1996) techniques, indicating that these methods are not applicable to roots in general, and that alternative, more reliable techniques are needed.