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

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