GERMINATION AND PHOTO-INDUCTION OF POLARITY IN THE SPHERICAL CELLS REGENERATED FROM PROTOPLASM FRAGMENTS OF BOERGESENIA-FORBESII

The processes of rounding (spheration) and cell wall formation of extracellular protoplasm fragments of Boergesenia forbesii were examined. This spheration depended on the presence of Ca2+ in the medium, and was accelerated exponentially with increasing temperature up to 35 C. At 25 C the regenerated cell wall could be detected within 3 hr, after the release of protoplasm into Provasoli's ES-medium. Germination, the development of a protrusion from the round cell, had an optimal temperature of 30 C and was interrupted at temperatures below 17 C. The germination was promoted by red-light irradiation (a maximum around 625 nm). This promotion depended on both irradiation time and light intensity, and was diminished by DCMU. Therefore, it was concluded that this promotion was caused predominantly through photosynthetic activity. The rhizoidal protrusion developed on the shaded side of a unilaterally irradiated round cell. Blue light was most effective in inducing cell polarity with light of wavelengths longer than 600 nm being ineffective. This wavelength-dependency was similar to that observed for polarity induction of Fucus eggs or in phototropism of Avena coleoptiles. © 1979 The Botanical Society of Japan.