Abstract: A method for the genetic modification and improvement of Porphyra species utilizing protoplast fusion is disclosed. The method of the invention features the use of conchoporangial branch conchocelis for at least one of the sources of protoplasts for protoplast fusion. Protoplasts produced from conchosporangial branch conchocelis of one species may be mixed with protoplasts produced from either blade material or conchocelis of a second species and fused using either a chemical fusing agent like polyethylene glycol (PEG) or electrofusion. Alternatively, an algal species other than a Porphyra species may be the second source of protoplasts. After fusion has occurred, fusion products are isolated and regenerated to whole plants or used as multicellular material.