Abstract
We studied super-low temperature preservation of moss (Pogonatum inflexum) protonemata. Pogonatum protonemata could be cultured both in MS and C1 medium. Addition of sucrose to C1 medium enhanced the growth of protonemata significantly, whereas MS medium was not suitable for the rapid growth of protonemata. Protonemata cultured in C1 medium were cryopreserved by the pre-freezing method. When protonemata were cultured in the mdium containing the higher concentrations (5 or 10%) of sugar, survival rates of the preserved cells were higher than that of the cells which was cultured with the lower concentration (1%) of sugar. Preculture of protonemata with abscisic acid was also effective for elevating the survival rate of preserved cells. From the morphological observations, number of round or oval-shaped cells increased when protonemata were cultured with higher concentration of sugar or abscisic acid. Thus, there may be important relation between morphology of protonema cell and its freezing tolerance.
