Early Physiological, Cytological and Antioxidative Responses of the Edible Halophyte Chenopodium quinoa Exposed to Salt Stress.

Quinoa ( Willd.) is a plant of South American origin recently valorized for its nutritional and nutraceutical properties in human diet. Quinoa is cultivated in many parts of the world, with a selection of varieties with good adaptability to extreme climatic conditions and salt stress. The variety Red Faro, native to southern Chile but harvested in Tunisia, was considered for salt stress resistance, considering its seed germination and 10-day seedling growth at increasing doses of NaCl (0, 100, 200 and 300 mM). Seedlings were spectrophotometrically analyzed for antioxidant secondary metabolites (polyphenols, flavonoids, flavonols and anthocyanins), antioxidant capacity (ORAC, oxygen radical absorbance capacity, DPPH*, 2,2-diphenyl-1-pic-rylhydrazyl), antioxidant enzyme activity (superoxide dismutase (SOD), guaiacol peroxidase (GPX), ascorbate peroxidase (APX) and catalase (CAT)) and mineral nutrient content in root and shoot tissues. Cytogenetic analysis of root tip was performed to check for meristematic activity and the possible presence of chromosomal abnormalities induced by salt stress. The results indicated a general increase in antioxidant molecules and antioxidant enzymes NaCl dose-dependent, no effects on seed germination but negative effects on seedling growth, and little effect on root meristems mitotic activity. These results indicated that stress conditions can induce an increase in biologically active molecules that could be used for nutraceutical purposes.