Potential production of polyphenols, carotenoids and glycoalkaloids in Solanum villosum Mill. under salt stress

Changes in the antioxidant defence systems were investigated in many aromatic and medicinal plants grown under salinity; however, no study is available about its effects on Solanum villosum Mill. In this study, we investigated the response of S. villosum to sodium chloride (NaCl), especially the impacts of NaCl on secondary metabolites production (phenolic compounds, carotenoids, and glycol-alkaloids). For this purpose, a hydroponic culture experiment was conducted on seedlings subjected to 0, 50, 100, or 150 mM NaCl. NaCl affected the growth of S. villosum in terms of plant height and dry weight, however, it increased the water content of the leaves. Although leaf Na+ concentration was significantly increased under salt stress, the leaves K+, Ca2+ and Mg2+ concentration were enhanced and/ or not significantly affected. The adaptation of S. villosum to NaCl stress was also reflected by the maintain of chlorophyll levels under different NaCl treatments. Additionally, leaf caffeic acid, lutein, and beta-carotene contents were considerably increased under 100 mM NaCl treatment, along with the up regulation of some related phenolic (phenylalanine ammonialyase and flavonol synthase), and carotenoid genes (phytoene synthase 1, phytoene synthase 2, and b-lycopene cyclase). The leaf contents of β-solamargine and α-solasonine also increased significantly with increasing salinity. The present study is the first to through some light on the medicinal quality of S. villosum that would be quite helpful for production of secondary metabolites under salt-stressed conditions.