Isolation and Characterization of a Long-Type Mutant in Phycocalidia Suborbiculata

Compared with Neoporphyra haitanensis (previously known as Pyropia haitanensis) that is a cultivar of nori in southern China, Phycocalidia suborbiculata (previously known as Pyropia suborbiculata) has higher heat resistance, but is not suitable for production and cultivation due to its round blades. In this study, a long-type mutant (PS-LT1) was isolated by using ultraviolet radiation to irradiate the blades of wild-type strain (PS-WT) of P. suborbiculata. Then the characteristics of PS-LT1 were analyzed and the results showed that the morphology of F1 gametophytic blades from the conchocelis of PS-LT1 was consistent with that of its parental blade, indicating that the long-form character could be stably inherited. At 30–60 days of age, the average length–width ratio of blades was about 6.7 in PS-LT1, which was 6.7-fold of that of PS-WT; the average absolute growth rate was 0.64 cm day−1 in PS-LT1, which was 3.8-fold of that of PS-WT. At 60 days of age, the average length and fresh weight of blades were 23.0 cm and 0.5 g in PS-LT1, which are 3.9- and 1.1-fold of those of PS-WT, respectively. At 25–45 days of age, the blades of both strains could continuously release archeospores, but the total number of released archeospores of PS-LT1 was 65.0% lower than that of PS-WT. In summary, PS-LT1 is a long-type mutant with the ability to release archeospores, which can be used as a material for breeding long-type improved strain of P. suborbiculata.