Regeneration from segments of sporelings in Myagropsis myagroides and Sargassum horneri

Regeneration from segments of sporelings in Myagropsis myagroides and Sargassum horneri was studied in laboratory culture. They were cut into a series of four segments: first leaf, upper portion of stem with basal part of first leaf and second leaf, lower portion of stem with basal part of rhizoids, and rhizoids. These segments were cultured for 2 weeks at 20°C under three different light intensities with 12L/12D. In M. myagroides cultured at 2000-2800lx, rhizoids regenerated from segments of the first leaf and the upper portion of the stem. More-over, both rhizoids and adventitious branches regenerated from segments of the lower portion of the stem. In S. horneri cultured at 2000-2800lx, rhizoids regenerated from segments of the upper portion of the stem, while adventitious branches regenerated from segments of rhizoids. Furthermore, both rhizoids and adventitious branches regenerated from segments of the first leaf and the lower portion of the stem. These results indicate that segments of the upper and lower portion of the stem of M. myagroides and a series of four segments of S. horneri have totipotency. Regeneration of segments was inhibited in both species cultured in total darkness and at 200-3001x.