Identification of currently cultivated Porphyra species by PCR-RFLP analysis

Porphyra yezoensis and P. tenera are the representative species of the marine crop Porphyra (nori) in Japan. Since the two species are extremely similar to each other in morphology, nori breeders have tentatively classified many strains of cultivated Porphyra into the two species without strict species identification. In order to facilitate rapid and reliable identification of the many strains of Porphyra currently cultivated in various Japanese regions, 24 conchocelis strains were examined by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis using the plastid RuBisCo spacer and the nuclear internal transcribed spacer regions. From the results, all the strains were identified as P. yezoensis f. narawaensis, and P. tenera was not detected. Hence, it was confirmed that most of the Porphyra strains currently cultivated in Japan are P. yezoensis f. narawaensis, and that intensive selective breeding has led to a reduced genetic diversity in the stock used for nori cultivation.