Abstract
Sugar kelp (Saccharina latissima) is an economically important species, and natural populations provide diverse and productive habitats as well as important ecosystem services. For seaweed aquaculture to be successful in newly emerging industry in Europe and other Western countries, it will have to develop sustainable production management strategies. A key feature in this process is the capacity to conserve genetic diversity for breeding programs aimed at developing seed stock for onward cultivation, as well as in the management of wild populations, as potentially interesting genetic resources are predicted to disappear due to climate change. In this study, the cryopreservation of male and female gametophytes (haploid life stage) of S. latissima by different combinations of two-step cooling methods and cryoprotectants was explored. We report here that cryopreservation constitutes an attractive option for the long-term preservation of S. latissima gametophytes, with viable cells in all treatment combinations. The highest viabilities for both male and female gametophytes were found using controlled-rate cooling methods combined with dimethyl sulfoxide 10% (v/v). Morphological normal sporophytes were observed to develop from cryopreserved vegetative gametophytic cells, independent of treatment. This indicates that cryopreservation is a useful preservation method for male and female S. latissima gametophytes.