Fig. 4.

Salt-induced PME activation is inhibited by CaCl₂ and EGCG application. (A) Root growth rate elongation in 7-day old Col-0 seedlings treated with mock, 125 mM NaCl (‘N’), 5 mM CaCl₂ or a combination of NaCl/CaCl₂ (‘NC’). Root growth rate elongation in 7-day-old Col-0 seedlings treated with mock, 125 mM NaCl, 5 mM CaCl₂ or a combination of NaCl/CaCl₂. Root growth rate is expressed as a ratio between NaCl and mock (‘N’) or NaCl/CaCl₂ and mock (‘NC’). Each of the dots represent the average length of two independent experiments (n=30 seedlings per treatment). Statistical comparisons were performed by using a Levene's test, followed by two-tailed, unpaired t-test; *P<0.05. (B) PME activity analyzed in 5 μg protein extracts spotted on plates containing highly methyl-esterified pectins with water (mock), 100 mM NaCl, 50 μM EGCG, a combination of NaCl and EGCG (NaCl/EGCG), 5 mM CaCl₂, a combination of NaCl and CaCl₂ (NaCl/CaCl₂), or 100 mM NaNO₃. Error bars indicate s.d. n=3. One-way ANOVA and Tukey's HSD (α=0.05) were used to compare treatments. Different letters indicate statistical significance between groups. (C) Six-day-old Arabidopsis Col-0 were treated for 24 h with water (mock, ‘m’), 100 mM NaCl (‘N’), 5 mM CaCl₂ (‘C’) or a combination of NaCl/CaCl₂ (‘NC’) (n=3) or DMSO (‘D’), 100 mM NaCl (‘N’), 50 μM EGCG (‘E’) or a combination of NaCl/EGCG (‘NE’) (n=3). Five micrograms of total sugars were extracted and dot blots performed using the 2F4 antibody.