Effect of benzoic acid hydroxyl- and methoxy-ring substituents on cucumber (Cucumis sativus L.) root membrane potential

Figures & data

Figure 1.  Benzoic acid derivatives used in this work.

Figure 2.  Effect of hydroxylated BAs upon membrane potential in cucumber (Cucumis sativus) root segments.

Figure 3.  Effect of methoxylated BAs upon membrane potential in cucumber (Cucumis sativus) root segments.

Figure 4.  Effect of benzoic acid derivatives on cucumber (Cucumis sativus) membrane potentials: depolarization and hyperpolarization with respect to controls. (A) 1 mM benzoic acid derivatives are added to control root segments; (B) Membrane depolarization and hyperpolarization with respect to controls of root segments from seedlings germinated in the presence of 1 mM of the various benzoic acid derivatives; (C) Effect of the addition of 1 mM of the appropriate benzoic acid derivatives on membrane potentials of seedlings germinated in the presence of 1 mM of the various benzoic acid derivatives. Bars indicate standard deviation. Values are expressed as mV.

Figure 5.  Relationship between the potency of BAs to induce hyperpolarization or depolarization and their octanol-water partition coefficient (Log P) in cucumber (Cucumis sativus) root segments. (A) significant positive correlation between Log P of controls and small Vm hyperpolarizing effects of GA and some hydroxymethoxy BAs; (B) Significant positive correlation between Log P and high Vm hyperpolarization induced by some methoxy-BAs; (C) Significant positive correlation between Vm depolarization and Log P of BA and some hydroxy-BAs.

Figure 6.  Effect of benzoic acid derivatives on K⁺−dependent membrane depolarization in cucumber (Cucumis sativus) root segments pre-incubated in 0.5 mM CaSO₄: membrane depolarization and hyperpolarization with respect to controls. (A) perfusion with 1 mM benzoic acid derivatives to controls root segments for 30 min followed by perfusion with 0.25 mM K₂SO₄. Controls are root segments perfused with 0.25 mM K₂SO₄; (B) Addition of 1 mM benzoic acid derivatives after membrane depolarization caused by perfusion of root segments with 0.5 mM K₂SO₄. Controls are root segments perfused with 0.25 mM K₂SO₄; C, effect of addition of 0.25 mM Cs₂SO₄ to root segments perfused as (B) Controls are root segments perfused with 0.25 mM K₂SO₄ and then with 0.25 mM Cs₂SO₄. Bars indicate standard deviation. Values are expressed as mV.

Figure 7.  Effect of benzoic acid derivatives on Fusicoccin (FC) membrane hyperpolarization in cucumber (Cucumis sativus) root segments pre-incubated in 0.5 mM CaSO₄: depolarization and hyperpolarization with respect to controls. (A) Addition of 1 mM benzoic acid derivatives to root segments perfused with 10 µM FC; (B) Addition of 1 mM benzoic acid derivatives to root segments perfused with 10 µM FC followed by perfusion with 0.25 mM K₂SO₄. Controls are root segments perfused with 10 µM FC followed by perfusion with 0.25 mM K₂SO₄. Bars indicate standard deviation.