Inhibition of blue light-dependent H+ pumping by abscisic acid through hydrogen peroxide-induced dephosphorylation of the plasma membrane H+-ATPase in guard cell protoplasts
by Zhang X., Wang H. B., Takemiya A., Song C .P., Kinoshita T., Shimazaki K. I. (2004)
, , , , ,
in Plant Physiol, 136 (2004), pp. 4150–4158. – DOI: https://doi.org/10.1104/pp.104.046573 –
Blue light (BL)-dependent H+ pumping by guard cells, which drives stomatal opening, is inhibited by abscisic acid (ABA).
We investigated this response with respect to the activity of plasma membrane H+-ATPase using Vicia guard cell protoplasts. ATP hydrolysis by the plasma membrane H+-ATPase, phosphorylation of the H+-ATPase, and the binding of 14-3-3 protein to the H+-ATPase stimulated by BL were inhibited by ABA at 10 μm.
All of these responses were similarly inhibited by hydrogen peroxide (H2O2) at 1 mm. The ABA-induced inhibitions of BL-dependent H+ pumping and phosphorylation of the H+-ATPase were partially restored by ascorbate, an intracellular H2O2scavenger. A single-cell analysis of the cytosolic H2O2 using 2′,7′-dichlorofluorescin revealed that H2O2 was generated by ABA in guard cell protoplasts.
We also indicated that H+ pumping induced by fusicoccin and the binding of 14-3-3 protein to the H+-ATPase were inhibited slightly (approximately 20%) by both ABA and H2O2. By contrast, H2O2 at 1 mm did not affect H+ pumping by the H+-ATPase in microsomal membranes.
From these results, we concluded that inhibition of BL-dependent H+ pumping by ABA was due to a decrease in the phosphorylation levels of H+-ATPase and that H2O2 might be involved in this response. Moreover, there are at least two inhibition sites by ABA in the BL signaling pathway of guard cells.