Initiation of gametophytic callus and somatic embryogenesis in <i>Laminaria japonica</i> (Phaeophyta) exposed to mutagenic agents
Zoospores of Laminaria japonica that settled on glass slides were irradiated at the germination stage with γ-rays in doses of 50, 100, and 250 Gy or exposed for 5 days to colchicine in a concentration of 4 × 10-5%. Cultivation was conducted for one month in vessels with sea water at a temperature 12°С and a light intensity of 4000 lx. Beginning on day 22, once a day, temperature was lowered for 12 h to 0°С. This led to the growth of female and male gametophytes that had not developed gametangia. By day 30, they appeared in the form of patches up to 2 cm across (1 to 2 per slide). Simultaneously, there were formations (1-2 per slide) consisting of strictly radially oriented series of somatic cells and adhering to the slide. Subsequently, the disc transformed into a cone of up to 0.5 cm in diameter. A single-layer diploid sporophyte of L. japonica emerged from the center of the cone.