Mechanism and Engineering of Polyamines on Growth, Regeneration and Callus Formation in Gracilaria corticata and G. verrucosa (Rhodophycea)

The role of Polyamines (PAs) has an important role on growth, regeneration and callus formation in Gracilaria corticata and G. verrucosa. The influence of different concentration of polyamines such as spermine, putrescine and spermidine enriched culture media was used during in vitro culture. Amongst different concentration of polyamines enriched media, spermine 10-6M enriched f/2 medium influences maximum number of vegetative branches and a callus (disorganized cell mass that arose from the organized tissue of the explant) formation. Although regeneration was observed in putrescine and spermidine supplemented enriched media but the speed of regeneration and growth was slow in compared to spermine. The simultaneous formation of filamentous outgrowth was observed at the cut ends of explants. These filamentous outgrowths later developed several vegetative branches cultured in different concentration of polyamines enriched media. The explants taken from the basal portion of the thallus showed maximum number of regeneration of vegetative branches compared to the apical portion. In G. corticata, some embryoids like structure (cystocarps) were observed in spermine 10-6M enriched PES medium. However, growth of cystocarps in G. verrucosa was observed on the surface of explants cultured in spermine 10-6M supplemented f/2 medium after 21 days of inoculation. Complete plantlet of G. corticata and G. verrucosa along with several branches was grown successfully in spermine supplemented enriched f/2 medium after 2 months of culture. The color of plantlets was bushy and quite similar to that of field material in appearance.