CULTURE AND DEVELOPMENT OF ELECTRICALLY FUSED PROTOPLASTS FROM RED MARINE-ALGAE, PORPHYRA-YEZOENSIS AND P-SUBORBICULATA

The electrically fused products of protoplasts from a wild type and a mutant strain of Porphyra yezoensis were cultured in a modified agar m edium, named ''soft agarose two-layer medium'' for 40 days, and then t ransferred and cultured subsequently in a liquid medium, In the soft a garose two-layer medium, fused products could be distinguished easily from unfused protoplasts. The survival rate of fused products in the s oft agarose two-layer medium was considerably higher than that of thos e in the liquid medium, However, growth rate of multi-cellular bodies which developed from fused protoplasts was higher when protoplasts wer e moved from the two-layer medium to liquid medium, The fused products repeated cell divisions and formed irregular-shaped multi-cellular bo dies. After 2 months of culture, a large number of cells in these cell ular bodies differentiated into monospores which then germinated and g rew to young thalli. Eventually, four out of approximately 180 fused p rotoplasts developed to young thalli, Morphologically hybrid-like thal li were obtained in an electrofusion experiment with protoplasts from Porphyra suborbiculata and a mutant strain of P. yezoensis, which sugg ested that genetic recombination would be possible between these two s pecies.