Improvement of Arabidopsis thaliana salt tolerance using a polysaccharidic extract from the brown algae Padina pavonica

Abstract Nowadays, the use of biostimulants in agriculture has become an innovative tool to cope with several environmental constraints. Seaweed extracts represent an interesting category of biostimulants which are gaining traction as agricultural applications. The present work aims at highlighting the effect of the aqueous extracts of the brown macroalgae Padina pavonica on growth, biochemical and molecular changes in Arabidopsis thaliana under salt stress. Five % (v/v) of P. pavonica extract seemed appropriate to offer an improvement of germination energy, fresh weight and root length. This seaweed extract at 5% concentration was also efficient in controlling NaCl applications. In fact, an increase of antioxidant activities (superoxide dismutase and catalase), biomass yield, proline and chlorophyll contents was observed whereas lipid peroxidation levels and reactive oxygen species were decreased. The expression profile analyses by real-time qPCR of some stress-related genes revealed the induction of superoxide dismutase, catalase and pyrroline-5-carboxylate synthetase in Arabidopsis thaliana growing in the MS medium supplemented with P. pavonica extract even in unstressed conditions. These results suggest that the use of P. pavonica extracts improves salinity tolerance in plants enhancing their reactive oxygen species scavenging ability.