Aquaporin as a membrane transporter of hydrogen peroxide in plant response to stresses

Hydrogen peroxide (H2O2) is a reactive oxygen species that signals between cells, and H2O2 signaling is essential for diverse cellular processes, including stress response, defense against pathogens, and the regulation of programmed cell death in plants. Although plasma membrane intrinsic proteins (PIPs) have been known to transport H2O2 across cell membranes, the perme-ability of each family member of PIPs toward H2O2 has not yet been determined in most plant species. In a recent study, we showed that certain isoforms of Arabidopsis thaliana AtPIPs, including AtPIP2;2, AtPIP2;4, AtPIP2; 5, and AtPIP2; 7, are permeable for H2O2 in yeast cells. Since the expression of PIPs is differently modulated in Arabidopsis by abiotic stress or H2O2 treatment, it is important to investigate the integrated regulation of aquaporin expression and their physiological significance in H2O2 transport and plant response to diverse abiotic stresses.