Callus induction and thallus regeneration of the red alga Meristotheca papulosa (Rhodophyta, Gigartinales)
Huang, W.; Fujita, Y.
Botanica Marina 40(1): 55-61
Suitable medium and culture conditions for callus induction from thallus explants and thallus regeneration in the red alga Meristotheca papulosa (Montagne) J. Agardh were examined. Axenic explants were obtained by treatment of thallus segments in iodine solution followed by an antibiotic mixture. The highest level of callus induction from axenic explants was obtained on ASP12NTA medium with 1.5% agar incubated at 20 degree C temperature and a photon flux density of 10 mu-mol photons m-2s-1. The callus was induced mainly from the cortical and medullary tissues at the cut surface and the callus cells were red pigmented. The callus cells were ellipsoidal or spherical and in the initial stages the cells were uniseriate, with time the callus grew irregularly. The callus induction rate was influenced by thallus collection time. The explants from thalli collected during December-May showed a higher rate of callus induction than the June-July collections. Addition of 0.1 mg L -1 indole-3-acetic acid (IAA) in combination with 0.05 mg L-1 6-benzylaminopurine (BAP) was effective in enhancing the callus size, but not the induction rate. Sucrose was most effective carbon compound tested, enhancing callus induction rate and size. Glycerol, mannitol and sorbitol showed an inhibitory effect. The excised callus from the explant showed sustained growth on subculture. The callus mass formed shoots when transferred to aerated PES liquid medium in 2 - 3 weeks. At 20 or 25 degree C, 40 mu-mol photons m-2s-1 were favourable for shoot formation. In 3 months these shoots regenerated 4.5 cm long thallus.