Endogenous brassinosteroids in microalgae exposed to salt and low temperature stress

Stirk W.A., Bálint P., Tarkowská D., Strnad M., van Staden J., Ördög V.

Keywords: Brassinolide, castasterone, homocastasterone, microalgae, salt stress, typhasterol
Abstract: Brassinosteroids are part of the hormonal network that regulates growth processes and stress responses in plants. There is evidence for a similar hormonal network in microalgae. In the present study, six microalgae (Chlorococcum ellipsoideum, Gyoerffyana humicola, Nautococcus mamillatus, Acutodesmus acuminatus, Protococcus viridis and Chlorella vulgaris) were subjected to salt and low temperature stress with the addition of 36 g l–1 NaCl and transfer from 25°C to 15°C. There was a rapid response to salt stress with the brassinosteroid content (mainly castasterone with lower amounts of brassinolide, homocastasterone and typhasterol) increasing within 30 min of the salt treatment and remaining at these elevated levels after 7 h. The decrease in temperature had little effect on the brassinosteroid content. This was the first study to show that endogenous brassinosteroids increase in response to abiotic stress in a number of microalgae species.
DOI: 10.1080/09670262.2018.1441447 IEB authors: Miroslav Strnad, Danuše Tarkowská