Effect of the Meristem on Sporification of Laminaria cichorioides

Isolated disks from vegetative thalli of Laminaria cichorioides Miyabe collected in April in Amursky Bay, Sea of Japan, cultivated separately from meristematic sites, developed sporangial sori after 4–6 weeks of cultivation, i.e., 4 months earlier than in natural conditions. The development of reproductive organs in intact plants, on meristematic sites, and also on vegetative disks, cultivated together with meristematic sites, was not observed. The effect of the meristem on L. cichorioides reproduction is supposed to be conditioned by inhibitors of sporification produced by this tissue. We offer a mechanism of sporification regulation for laminarian algae in natural conditions.