Acquisition and maintenance of environmental stress memory in red algae ‘Bangia’ spp.
Authors
Puja Kumari (presenting author) [1, 2]
Koji Mikami [1, 3]
Keywords
Bangia; stress memory; priming; thermotolerance; salinity stress; seawater dilution
Abstract
Seaweeds often acquire species-specific and stress stimuli-dependent acclimatory responses to survive in the marine environment. Understanding the acquisition and maintenance of such tolerance mechanism may provide pertinent tool for building environmental resilience. The ability of seaweeds to memorize their past experiences to better acclimate to the changing environment is not much studied. Generally, higher plants acquire a memory after exposure to external stimulus that enable the plants to respond to subsequent stress events with a faster and a stronger defense. This memory persist as a ‘primed state’ even if the stimulus no longer exist. However, the understanding of such stress memory concept is limited in seaweeds. Bangia species is a filamentous red seaweed belonging to Bangiophyceae cultivated commercially in South-East Asia. We have showed that Bangia sp. acquire thermotolerance based on heat stress memory, but the memory is transient and highly variable among different Bangia species. In this study, we investigated the role of stress memory in conferring tolerance to the dilution of seawater that causes hyposalinity, hypoosmatic and low nutrient stress simultaneously. ‘Bangia’ sp. ESS1 gametophytes primed with different diluted seawater concentrations for one week showed faster and stronger stress memory responses to recurrent dilution of seawater during triggering stress, which lasted for two weeks. The primed algae showed higher cell viability accompanied with low levels of floridosides and most of the central carbon metabolites during exposure to diluted seawater. This indicated that ‘Bangia’ sp. ESS1 may memorize past stress responses to acclimatize to fluctuating seawater conditions in the marine environment.
Funding
JSPS KAKENHI (Grant Numbers 25660160 and 18F18388) JSPS postdoctoral fellowship was awarded to Dr. Puja Kumari