Aquaporins facilitate hydrogen peroxide entry into guard cells to mediate ABA- and pathogen-triggered stomatal closure.
Stomatal movements are crucial for the control of plant water status and protection against pathogens. Assays on epidermal peels revealed that, similar to abscisic acid (ABA), pathogen-associated molecular pattern (PAMP) flg22 requires the AtPIP2;1 aquaporin to induce stomatal closure. Flg22 also induced an increase in osmotic water permeability (Pf) of guard cell protoplasts through activation of AtPIP2;1. The use of HyPer, a genetic probe for intracellular hydrogen peroxide (H2O2), revealed that both ABA and flg22 triggered an accumulation of H2O2 in wild-type but not pip2;1 guard cells. Pretreatment of guard cells with flg22 or ABA facilitated the influx of exogenous H2O2 Brassinosteroid insensitive 1-associated receptor kinase 1 (BAK1) and open stomata 1 (OST1)/Snf1-related protein kinase 2.6 (SnRK2.6) were both necessary to flg22-induced Pf and both phosphorylated AtPIP2;1 on Ser121 in vitro. Accumulation of H2O2 and stomatal closure as induced by flg22 was restored in pip2;1 guard cells by a phosphomimetic form (Ser121Asp) but not by a phosphodeficient form (Ser121Ala) of AtPIP2;1. We propose a mechanism whereby phosphorylation of AtPIP2;1 Ser121 by BAK1 and/or OST1 is triggered in response to flg22 to activate its water and H2O2 transport activities. This work establishes a signaling role of plasma membrane aquaporins in guard cells and potentially in other cellular context involving H2O2 signaling.
['Rodrigues|Olivier|O|', 'Reshetnyak|Ganna|G|', 'Grondin|Alexandre|A|', 'Saijo|Yusuke|Y|', 'Leonhardt|Nathalie|N|0000-0002-5392-9732', 'Maurel|Christophe|C|', 'Verdoucq|Lionel|L|0000-0001-8238-3700']
D000040:Abscisic Acid D020346:Aquaporins D017360:Arabidopsis D029681:Arabidopsis Proteins D006861:Hydrogen Peroxide D000069452:Pathogen-Associated Molecular Pattern Molecules D010766:Phosphorylation D010935:Plant Diseases D054046:Plant Stomata D011494:Protein Kinases D017346:Protein Serine-Threonine Kinases D044224:Pseudomonas syringae D015398:Signal Transduction
aquaporin hydrogen peroxide stomatal movement pathogen guard cell signaling