Growth of A. thaliana plants under different illumination sources. A) Bolting age of Arabidopis plants. n = 15 (fluorescent), n = 11 (LED). B) Measurement of chlorophyl content at different time points. n = 15 plants (mean from 3 leaves from one plant). C) Fresh weight at different time points. n = 11 (25; 42 days), n = 6 (36 days). D) Relative expression of PR-1 gene in 5 weeks old plants after treatment with 300 μM NaSA. Values represent 2 independent samples from 2 biological replicates. The PR-1 expression was normalized to reference gene SAND. In all cases error bars represent SD. Asterisks indicate statistically significant differences compared to plants grown under fluorescent lights (*P < 0.05; two tailed Student’s t-test).