Glycerol-activated cellular division and biosynthetic activity during growth and morphogenesis of carpospore seedlings of Grateloupia doryphora (Cryptonemiales, Rhodophyta)

Abstract The red alga Grateloupia doryphora (Montagne) Howe was grown in axenic culture in Provasoli's enriched seawater medium supplemented with glycerol as an organic carbon source. Carpospore seedlings showed a particular form of cell proliferation forming compact cell masses with many buds or protrusions after 12 days of growth. Histologic and histochemical techniques and studies at the electron microscope level revealed: (1) a short-term effect in which cell division was activated within 2 h in the internal cell layer of the carpospore seedling, and (2) buds derived from internal cell proliferation on the periphery. Glycerol was used to biosynthesize polymers needed for cell elongation and division as evidenced by starch accumulation and endomembrane system activity. When morphogenesis was completed, the regeneration capability remained with the internal cells that maintained their cell structure, including chloroplasts, and accumulated compounds in large vacuoles. These cells recommenced growth if c...