Trehalose mediates salinity-stress tolerance in a crustacean

Abstract

AbstractSalinization poses an increasing problem worldwide, threatening freshwater organisms and raising questions about ability to adapt. We explore the mechanisms enabling a planktonic crustacean to tolerate elevated salinity. By gradually raising water salinity in clonal cultures from 185Daphnia magnapopulations, we showed that salt tolerance strongly correlates with native habitat salinity, indicating local adaptation. A GWAS revealed a major effect of theAlpha,alpha-trehalose-phosphate synthase(TPS) gene, suggesting that trehalose production facilitates salinity tolerance. We found a positive correlation between water salinity and trehalose concentrations in tolerant animals, while intolerant animals failed to produce trehalose. Using CRISPR/Cas9, a silencedTPSgene supported the role of trehalose under salt stress. Our study highlights how a keystone freshwater animal adapts to salinity stress using an evolutionarily conserved mechanism known in plants and bacteria, but not in metabolic-active animals.HighlightsSalinity tolerance is a locally adapted trait inDaphnia magnaThe trehaloseTPSgene shows a strong association with salinity toleranceTrehalose content increases with water salinity allowing survival of tolerant genotypesNon-functionalTPSgenes reduce salinity tolerance by preventing trehalose production