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Seaweeds are an important primary producer in the ocean and a highly diverse group, including species with various types of life cycles and reproductive systems. Recent advances in next-generation sequencing technology have made it easier to obtain genomic information even in seaweeds. Besides, genome editing technology is making it possible to analyze gene functions in seaweeds. By combining these new technologies with culture experiments and morphological observations, we attempt to understand the sexual reproduction mechanism, evolution of reproductive mode, environmental adaptation, and species diversity in seaweeds.

left: Seaweeds in spring sea at Muroran, right: Ulva sp.

left: Female gametes of Ulva prolifera, right: Gamete fusion observed by SEM

References

• Ichihara, K., Yamazaki, T., Miyamura, S. et al. Asexual thalli originated from sporophytic thalli via apomeiosis in the green seaweed Ulva. Sci. Rep. 9, 13523 (2019). https://doi.org/10.1038/s41598-019-50070-x
• Yamazaki, T., Ichihara, K., Suzuki, R. et al. Genomic structure and evolution of the mating type locus in the green seaweed Ulva partita. Sci. Rep. 7, 11679 (2017). https://doi.org/10.1038/s41598-017-11677-0
• Ichihara, K., Shimada, S. & Miyaji, K. Systematics of Rhizoclonium-like algae (Cladophorales, Chlorophyta) from Japanese brackish waters, based on molecular phylogenetic and morphological analyses. Phycologia 52, 398 – 410 (2013). https://doi.org/10.2216/12-102.1
• Ichihara, K., Arai, S., Uchimura, M. et al. New species of freshwater Ulva, Ulva limnetica (Ulvales, Ulvophyceae) from the Ryukyu Islands, Japan. Phycol. Res. 57, 94-103. (2009). https://doi.org/10.1111/j.1440-1835.2009.00525.x