Phenolic responses of the halophytic vegetable Salicornia europaea to UVB radiation

Salt-tolerant crops offer an alternative to conventional farming under freshwater-limited conditions. Salicornia europaea is a promising alternative vegetable offering a valuable nutritional profile, including phenolic compounds and other health-promoting secondary metabolites. UVB radiation activates plant defence pathways, stimulating the antioxidative system and secondary metabolite accumulation. In controlled indoor-farming systems, UVB can be applied as an eustress factor to enhance antioxidant accumulation ( e.g. phenolic compounds). Building on previous findings that UVB increased carotenoid accumulation in S. europaea , this study investigated the influence of four UVB treatments on phenolic compound accumulation. This was achieved by determining total antioxidant capacity and phenolic content using in vitro assays, and the phenolic profile using HPLC-DAD and HPLC-MS/MS. The results revealed that the total antioxidant capacity and total phenolic content increased under all UVB treatments. The most abundant phenolic compound was chlorogenic acid, which also showed a response to UVB at all radiation levels. Ferulic acid and quercitin-3- O -glycoside showed an increased content in response to all UVB treatments, while others such as, rosmarinic or caffeic acid, showed only to one or none treatment a response. Correlations were observed between the total antioxidant capacity and the total phenolic content, as well as between the total antioxidant capacity and most of the individual phenolic compounds. In conclusion, this study demonstrates that UVB radiation induces the accumulation of phenolic compounds and activates the antioxidant system in S. europaea grown in indoor farming. Although the UVB response is very complex, these findings could be used to improve the nutritional profile of S. europaea and supports its potential as an alternative crop for saline cultivation.