Salicylic acid modulates primary and volatile metabolites to alleviate salt stress-induced photosynthesis impairment on medicinal plant Egletes viscosa

Abstract Plant responses to salinity have been long investigated. Nevertheless, how leaf metabolism is affected, and what is the role of salicylic acid (SA) during salt stress remains elusive. Here we evaluated the influence of exogenous SA on the growth, primary and secondary metabolism of the medicinal plant Egletes viscosa under salt stress. Salinity decreased plant biomass, leaf gas exchange, and photosynthetic pigment content. The principal component analysis revealed that both SA and salt altered leaf metabolite profile when analyzed isolated or in combination. Salinity increased several amino acids contents. In contrast, slight changes in the level of organic acids and sugars were observed. Exogenous SA also increased the content of almost all volatile organic compounds (VOCs) identified. The integrative effect of salt and exogenous SA did not reverse the effects of salinity on the plant biomass, nor did it restore VOCs profile. However, SA was able to increase K+ levels, and decrease H2O2 overproduction in salt-stressed plants by increasing key metabolites, which leads to a higher net photosynthetic rate. Taken together, our results suggest that SA increased several metabolites which may contribute to the portioning of Na+ and K+ among roots and shoots alleviating salt stress-induced photosynthesis impairment by modulating key primary and volatile metabolites.