Plastid-located flavodoxin protects NaCl-exposed leaf tissue from salt toxicity.

<p>Leaf discs from 2-month-old WT and <i>pfld</i> plants grown in soil were incubated at different NaCl concentrations for various times (A). Chlorophylls (Chl) and carotenoids (Car) were determined at 72 h of treatment (B), whereas the photosynthetic parameters (C) were measured after 24 h of salt exposure. Experimental details are given in Materials and Methods. In (B) and (C), the means and standard deviations (SD) of 6 independent assays are reported. Different letters indicate significant differences at P ≤ 0.05, according to two-way ANOVA and Holm-Sidak multiple range tests.</p

Chloroplast flavodoxin does not prevent the decline of osmotic pressure and viability in salt-exposed tobacco roots.

<p>Twelve-day-old seedlings were incubated for 15 days with 0.25 M NaCl in MS0-agar plates and the osmotic potential (ψ) of excised whole roots was determined as described in Materials and Methods (A). The osmolarity of replicate samples was also measured in cleared extracts (B) using a freezing point osmometer. Each value is the mean of 6 replicates plus SD. For the evaluation of root and leaf viabilities, 12-day-old seedlings were salt-treated as in panels A and B, except that incubation was limited to 11 days. Metabolic activities were determined in cleared leaf (C) and root (D) extracts by the TTC reduction procedure [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0159588#pone.0159588.ref045" target="_blank">45</a>]. Means and SD values were determined by averaging 6 independent experiments. Different letters indicate significant differences at P ≤ 0.05, according to two-way ANOVA and Holm-Sidak multiple range tests.</p