A simple and highly efficient method for the cryopreservation of Laminaria japonica (Phaeophyceae) germplasm.

Spores of Laminaria japonica were cryopreserved in liquid nitrogen. Dimethyl sulphoxide was found to be the most effective and least toxic cryoprotectant for cryopreservation of spores of L. japonica. By comparing the post-thaw viability of cryopreserved spores, rapid or gradual cooling procedures were found to be suitable means to cool spores. Following a process of gradual cooling, 24 h storing in liquid nitrogen and quick thawing, 50% of cryopreserved spores remained viable. Such spores developed into gametophytes, which retained the potential to form gametophyte clones or to give rise to sporophytes. Significantly greater numbers of male gametophytes than female gametophytes were observed to develop from thawed spores. The cryopreservation of spores of L. japonica is not only simple to perform but permits the cryopreservation of many strains with minimal requirements of both labour and space. [ABSTRACT FROM AUTHOR]