Occurrence of glycerol uptake in D unaliella tertiolecta under hyperosmotic stress

The unicellular halotolerant green alga species D unaliella are able to proliferate in extremely varied salinities by synthesizing intracellular glycerol and adjusting the cell shape and volume. However, some marine D unaliella species such as D unaliella tertiolecta are not able to regulate cell volume as an immediate response to counter external osmotic shock. Here we report that a rapid shock‐response mechanism is present in D unaliella tertiolecta , involving uptake of exogenous glycerol in response to hyperosmotic shock without changing cell volume, and this glycerol uptake activity is associated with the D unaliella tertiolecta glycerol uptake protein 1 ( Dt GUP 1 ) gene, which belongs to the membrane‐bound O ‐acyltransferase. The mutant Dt GUP 1‐E , in which the Dt GUP 1 gene is silenced, displayed an inability to take up glycerol from the medium and showed cell death under hyperosmotic shock. To our knowledge, this is the first time a gene product has been reported in D unaliella tertiolecta that is involved in glycerol uptake activity under hyperosmotic stress.