Free amino acid contents of the gametophytic blades from the green mutant conchocelis and the heterozygous conchocelis in Porphyra yezoensis Ueda (Bangiales, Rhodophyta)

Free amino acid contents in green mutant (G-1) blades and sectored F-1 gametophytic blades with green and wildtype portions. which were developed from heterozygous conchocelis obtained by a cross between the wild type (0110) and the green mutant (G-1) of Porphyra yezoensis, were compared with those of the wild-type blades in laboratory culture. The contents of the major four free amino acids (aspartic acid, glutamic acid, alanine and taurine) as well as those of the total free amino acids were highest in the green mutant blades, intermediate in the F-1 gametophytic blades, and lowest in the wild-type blades. A similar trend was obtained in the blades developed from monospores of the F-1 gametophytic blades. In addition, the green-type sectors also had a higher content of the four major free amino acids and total free amino acids compared with the wild-type sectors in the F-1 blades cultivated at a nori farm. The green mutant is characterized by higher contents of the four major free amino acids compared with the wild type, which has a higher growth rate. Hence, it is considered that the sectored F-1 gametophytic blades produced from the heterozygous conchocelis have both parental advantages (high free amino acid contents and high growth rate) and compensate for both parental disadvantages. This seems to be one of the possible ways of genetic improvement in regards to the taste of nori and stable production in Porphyra cultivation.