Gelling agents for tissue culture of the seaweed Hizikia fusiformis

Callus and blade formation of the seaweed Hizikia fusiformis depended on the gelling agents used under axenic culture conditions. Excised cylindrical pieces (5 mm) of the hold fast were cultured on seven different gelling agents in seawater with added Provasoli's enrichment (PESI), at 40 µmol m^?2 s^?1 light intensity, 18 ?C for 1 month. The highest percent of callus formation (47%), from holdfast pieces, was produced on solid medium composed of 2.0% high gel strength agar. No callus was formed in liquid medium. Blades, from holdfast pieces, were formed in PESI liquid medium at the rate of 45%, while the high level of axenic blade formation (30%) on solid support was observed on 0.5% high gel strength agar. Callus and blade were identified with the original strain, at the DNA level, using random amplified polymorphic DNAs.