Selection and characterization of an improved strain produced by inter-species hybridization between Pyropia sp. from India and Pyropia haitanensis from China

A crossing-experiment between Pyropia sp. from India and P. haitanensis from China was carried out for breeding improved strains. The male parent was the wild-type strain (Ps-WT01) of Pyropia sp., which was characterized by thick blade, slow growing, good toughness and more production of conchospores, and the female parent was the mutation strain (Ph-HMC5) of P. haitanensis, which was characterized by thin blade, fast growing, poor toughness and low production of conchospores. At first, four improved strains with obvious recombinant advantages were obtained from the F1 color-sectored blades, and finally the most improved strain (HR-5) was selected from them. The maximum of absolute growth rate of the male and female parents were 0.39 and 5.24 cm/d, respectively, while that of HR-5 strain was 10.11 cm/d and its absolute growth rate was greater than the maximum growth rate of the female parent during 41-55 days of culture. After 60 days, the mean blade length of HR-5 was 168.67 cm, which was 12.80-fold of that (13.18 cm) of its male parent and 1.97-fold of that (85.67 cm) of its female parent, respectively. The chlorophyll a content in the 35-day-old blades of HR-5 strain was 10.57 mg/g, which increased by 68% and 35% compared with that of its male and female parents, respectively. The phycobiliprotein content of HR-5 blades was 114.88 mg/g, which was 2.51- and 2.01-fold of that of its male and female parents, respectively. The mean thickness of the 35-day-old blades of HR-5 was 25.06 μm, which was 60% and 124% of that of its male and female parents, respectively. The total number of conchospores per shell released from HR-5 was 404.14 × 104, which was 2.73- and 6.38-fold of that of its male and female parents, respectively. The above results confirmed that HR-5 strain was characterized by fast growth, high quality as well as large amount of conchospores, and may offer an alternative for the nori industry.