Induction and isolation of pigmentation mutants of Porphyra yezoensis (Bangiales, Rhodophyta) by heavy‐ion beam irradiation

SUMMARY The present study describes the isolation of pigmentation mutants of Porphyra yezoensis Ueda induced by heavy‐ion beam irradiation for the first time. The gametophytic blades were irradiated with 12 C +6 ion beams within a dose range of 25–400 Gy. From the survival rate and cell growth of the irradiated blades, it is suggested that a dose of 150 Gy or less is suitable to induce mutation for the isolation of mutants of P. yezoensis . After irradiation, red, green and deep reddish brown‐colored gametophytic blades developed from archeospores that were released from each of the mutated cell clusters of the respective different colors, and the red mutant strain (IBY‐R1) and green mutant strain (IBY‐G1) were established as a conchocelis colony in culture. Blades of the mutants were characterized by their growth and photosynthetic pigment contents compared with those of the wild‐type. From these results, it is clear that heavy‐ion beam mutagenesis will be an effective tool for genetic and breeding studies of Porphyra , and also for other algal research.