Effects of exogenous betaine on physiological characteristics and tropidine alkaloid content in Atropa belladonna L. under NaCl stress

In this study, Atropa belladonna L. seedlings were sprayed with different concentrations (20 mmol/L and 40 mmol/L) of betaine (glycine betaine, GB) under artificial simulated 100 mmol/L salt stress to investigate the effects on physiological characteristics and tropane alkaloid content in Atropa belladonna L. Compared with NaCl stress treatment, exogenous betaine enhanced the photosynthesis of Atropa belladonna L. leaves, with superoxide (SOD), peroxidase (POD), and catalase (CAT) activities increasing to different degrees; malondialdehyde (MDA) content decreased significantly; nitrate nitrogen, soluble protein, and free amino acid content and nitrate reductase (NR), glutamine synthetase (GS), and glutamate dehydrogenase (GDH) activities increased significantly. The contents of precursor amino acids (ornithine and arginine) and tropane alkaloids (scopolamine and scopolamine) in the secondary metabolic pathway of Atropa belladonna L. also significantly increased. Our results indicated that 100 mmol/L salt stress treatment inhibited the growth of belladonna, and 20 mmol/L betaine treatment could alleviate this damage.