Abstract
Because of their sessile nature, intertidal aquatic seaweeds are usually
exposed to changes in living conditions as environmental stresses. Thus,
acclimation and acquisition of tolerance to these stresses are
indispensable for their sustainable survival. We here summarized two
topics of our recent studies on physiological strategies of Bangiales for
survival under stressful conditions. (1) Life cycle trade-off: Excision of
explants from gametophytes of Pyropia yezoensis accelerated
release of monospores and carpospores that were generated via the
activation of asexual and sexual reproductive processes, respectively. In
contrast, heat stress at sub-lethal 25℃ stimulated the production of a
callus, from which new gametophytic thalli with a normal shape were
generated asexually. Thus, wounding and heat stress differently promote
the life cycle trade-off that can reset the timing of reproduction. (2)
Stress memory: When Bangia sp. ESS1 was exposed to sub-lethal high
temperature 28℃, strong tolerance to lethal high temperature 32℃ was
established. Since thermotolerance was maintained after returning to
standard growth temperature 15℃ for several days, it was concluded that Bangia
sp. ESS1 can acquire memory of heat stress to protect themselves against
exposure to lethal high temperature. These findings demonstrate the
presence of a variety of distinct survival and growth strategies in
Bangiales to cope with different environmental stress
conditions.
