The expression of NPX1 was up-regulated by nutrient deprivation and abiotic stresses. Quantitative real-time PCR analysis of NPX1 under nutrient-deprived and abiotic stress conditions and ABA treatment is shown. A, Arabidopsis ecotype Columbia roots grown under nutrient-sufficient conditions, K+ deficiency (−K), N deficiency (−N), and P deficiency (−P) 6 or 30 h after incubation. B, Expression of NPX1 in the whole seedlings after treatment with 100 mm NaCl for 1, 3, 6, and 24 h. C, Expression of NPX1 in the whole seedlings after cold stress (4°C) for 1, 3, 6, 24, and 48 h. D, Expression of NPX1 in the whole seedlings after 100 μm ABA treatment for 1, 3, 6, and 24 h. Data represent means of three biological replicates. Asterisks indicate significant differences (* P < 0.05, ** P < 0.01, by Student's t test).