Protoplast isolation and regeneration in the marine red alga Porphyra nereocystis.

We have developed a method for isolating viable protoplasts from the blade phase of the epiphytic marine red alga Porphyra nereocystis Anderson, using a two-step enzymatic digestion with commercially available enzymes. The first step uses papain, the second step uses abalone acetone powder. The method is rapid and gives a high yield of viable protoplasts. In liquid culture in enriched seawater medium, the protoplasts can undergo regeneration along three pathways: they directly form filaments resembling the conchocelis phase of Porphyra; they form calli with relatively thick-walled, pigmented cells; and they indirectly form blades from the edges of these calli. Porphyra nereocystis protoplasts also may serve as an alternative propagation method in aquaculture and be useful for studies of cell-wall formation, cell division, and thallus differentiation. They may also be used in somatic selection, somatic hybridization and gene-transfection experiments.