Light and glycerol driven development of Grateloupia doryphora (Rhodophyta) in vitro
R.R. Robaina, P. García Jiménez and A. Luque
The implications of light in structural changes during growth and development of a carpospore seedling from Grateloupia doryphora cultivated in glycerol were studied by changing photon flux density from the standard white light of 30 µmol photons m-2s-1 to 20, 60 and 100 µmol photons m-2s-1 and spectra from white to both blue and red light (30 µmol photons m-2s-1 of 450 and 640 nm respectively). The growth rate as well as morphogenesis (bud, shoot or simply production of new axes) increased with the photon fluence rate of white light, as well by changing cultures from white to both blue and red light. Friability was higher in blue and red light and when carpospore-seedlings were cultivated under the highest photon fluence rates. At structural-ultrastructural level it was observed that glycerol and light (in any light condition tested) promoted a short term induction of cell division and biosynthesis in the former cells of the carpospore-seedling. As a result, new cell layers were formed concentrically arranged with respect to former cells. The division of these cells lead to the formation of the new axes (morphogenesis). The accumulation and later degradation of starch and intense proliferation of endomembranes accompanied morphogenesis.