Effect of plant growth regulators on direct regeneration and callus induction from Sargassum polycystum C. Agardh

Abstract

Seaweed tissue culture is one of the potential technologies that can be used to increase seaweed production to cope with increasing demand. Seaweed tissue culture can be divided into two methods, namely, direct regeneration and callus induction (indirect regeneration). These methods provide several advantages, including generating seaweed cultures that are disease-free and able to mature faster to support mass production. The present study aims to develop a suitable protocol for tissue culture of Sargassum polycystum C. Agardh. We investigated different methods of sterilizing the stipe, stolon and leaf explant surfaces to allow for axenic tissue growth. In addition, we also investigated the effects of different plant growth regulators (PGRs) on seaweeds that are grown via direct regeneration and callus induction method. Our results showed that a combination of physical (brushing using soft brush under microscope) and chemical treatments (detergent, povidone iodine (PI) and antibiotic solution of streptomycin sulphate) was most suitable for growing axenic stipe of S. polycystum. For obtaining axenic leaf and stolon explants, the best treatment option was using germanium oxide (GeO 2 ) as a pre-treatment, followed by treatments with detergent, PI and streptomycin sulphate antibiotic solution. We tested the effects of nine different plant growth regulators on the growth of tissue explants, which include indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), 1-napthaleneacetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), picloram, forchlorfenuron (CPPU), uniconazole, 6-benzylaminopurine (BAP) and kinetin. Results showed that only bud explant was able to induce callus growth when treated with kinetin (4.65 μM and 13.94 μM) and uniconazole (3.00 μM, 7.00 μM and 10.00 μM). In addition, only stipe explant showed regeneration of adventitious bud when grown in the absence of plant growth regulators.