Exogenous trehalose alleviates the inhibitory effects of salt stress in strawberry plants

We investigated the role of trehalose (Tre) root pretreatment (10 and 30 mM) in photosynthesis, phenolic metabolism, antioxidant properties and ion homeostasis of strawberry plants when exposed to 50-mM NaCl for 7 days. Salinity caused an adverse effect on the shoot dry weight, whereas root pretreatment with 30-mM Tre mitigated these inhibitory effects. Under no stress, development of flowers was greatly enhanced by the supply of Tre. Plants exposed to salt stress after root pretreatment with 30-mM Tre maintained their photosynthetic electron transport rate, compared with NaCl-alone-treated plants, contributing to the improvement of photosystem Performance Index (PIabs), and oxygen-evolving complex efficiency of PSII (Fv/Fo). Although NaCl stress resulted in the highest Na accumulation, the application of Tre reduced shoot Na accumulation. In addition, the oxidative burst and lipid peroxidation observed in plants subjected to salinity conditions was greatly mitigated after root pretreatment with 30-mM Tre, as evidenced by lower malondialdehyde and superoxide radical (O2·−) levels, compared with NaCl-alone-treated plants. To sum up, root pretreatments with 30-mM Tre were more effective than with 10-mM Tre in alleviation of salt stress in strawberry. This positive effect of Tre was possibly attributed to the improvement of carotenoids, flavonoids and anthocyanins compounds in leaves resulting in normal photochemical functioning, the activation of the enzymatic antioxidants and the compartmentalization of Na for better growth under salt stress.