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High throughput culture and gametogenesis induction of Laminaria japonica gametophyte clones
- Zhang, Quan Sheng, Qu, Shan Cun, Cong, Yi Zhou, Luo, Shi Ju, Tang, Xue Xi
- Journal of applied phycology 2008 v.20 no.2 pp. 205-211
- Laminaria, Saccharina japonica, bottles, clones, correlation, eggs, females, gametogenesis, gametophytes, light intensity, males, mixed culture, models, photoperiod, sporophytes, China
- In anticipation of the application of a new sporeling-raising method using gametophyte clones to Laminaria commercial cultivation in China, techniques of mass culture and gametogenesis induction of L. japonica gametophyte clones were developed, as a mass of fertile gametophytes is a prerequisite for sporeling-raising with the new method. Gametophyte clones which were subjected to fed-batch culture exhibited a classical logistic growth curve. Growth rates decreased gradually after 2 months of culture, and were negatively correlated to cell density. UNOVA also showed that only cell density has a significant effect on the growth of gametophyte clones under the experimental conditions. Based on the dynamics models revealed, a culture strategy only directed at the control of cell density was adopted. By this strategy, a total of 36 kg wet weight from an initial weight of 0.75 kg was achieved after 3 months culture in 100 20-L bottles. The final average density reached 24 g L⁻¹. For the subsequent gametogenesis induction, amplificatory male and female gametophyte clones were cut, mixed and cultured in bottles under the same conditions used in amplification except for a change of photoperiod from continuous irradiance to 10 h light: 14 h dark cycle. Egg discharge occurred 10 days after the mixed culture and increased gradually with the culture duration. Most gametophytes gave rise to sporophytes 20 days after induction. Large-scale culture of gametophyte clones and gametogenesis induction for commercial cultivation in 2003-2005 have been conducted successfully.