Effect of chelated iron in culture media on oogenesis in Laminaria angustata.

Female gametophytes of Laminaria angustata KJELLMAN formed oogonia in PESI medium but scarcely formed them in ASP12 NTA medium at 10°C, 14 h light-10 h dark cycle and 2, 000-3, 000 lx. The oogenesis eddects of nitrate, phosphate, iodine, boron, iron, manganese, zine and cobalt were investigated in ASP12 NTA as a basal medium. Under this condition, nitrate, phosphate, manganese, zinc and cobalt were not effective in oogonium formation. Iodine seemed to be slightly effective. Boron had a tendency to inhibit oogonium formation. However, iron strongly induced oogomiu, formation of L. angustata, and most female gametophytes formed oogonia at 2.0mg/l EDTA chelated iron after two weeks, at which time almost all cells of female gametophytes became eggs. These eggs developed into parthenogenetic sporophytes which showed abnormal morphology.