Abstract
Marine diatoms account for about a quarter of primary production and can grow in a wide range of salt. Although salt is a perturbable factor at the ocean surface, acclimation mechanisms in marine photoautotrophs to low salt environment have not been reported. In this study, low-salt-response was characterized in the marine diatom Phaeodactylum tricornutum. Cells were transferred from standard (0.5M[Na+]) to low salt (0.1M[Na+]) seawater and growth profile was monitored. RNA was obtained from each acclimation stages, pre-, early-stage- and late-stage accumulations, and a semi-exhaustive transcriptome analysis was carried out using cDNA-amplyfied fragment length polymorphism (cDNA-AFLP) technique. Consequently, 74 cDNA-fragments were detected as low-salt-response genes. Of these, cDNA encodes Heat shock factors, ascorbic acid (AsA) biosynthesis, AsA redox processes, and other reactive oxygen scavenging enzymes were shown to be increased during acclimation to low salt. These results indicate that acclimation to low salt is accompanied by oxidative stresses.
