Cell suspension culture from Porphyra linearis (Rhodophyta) a multicellular marine red alga

A cell-suspension culture suitable for continuous propagation was established from protoplasts of the red alga Porphyra linearis Grev., an edible, winter annual species of nori. Protoplast-derived cells that did not regenerate into thalli were used to establish a culture line of uniform-sized (average about 25 mu m diam.) cells, which resembled the vegetative cells of this species in the leafy thallus phase. Cell division occurred about once per 24 to 30 h in uncrowded (1-2 cells per culture well) culture. This cell-suspension culture has now been maintained as continuously growing subcultures for more than four years without formation of organized thalli; however, the latter can be obtained at will by altering culture conditions (lowering temperature from 20 degrees to 10 degrees C, lengthening photoperiod from 10: (14) over bar or 8: (16) over bar to 14: (10) over bar or 16: (8) over bar and increasing irradiance from 10 to >= 30 mu mol m(-2) s(-1)). This appears to be the first continuous non-clonal cell-suspension culture developed for a multicellular alga.