Hydrogen peroxide permeability of plasma membrane aquaporins of Arabidopsis thaliana

Although aquaporins have been known to transport hydrogen peroxide (H2O2) across cell membranes, the H2O2-regulated expression patterns and the permeability of every family member of the plasma membrane intrinsic protein (PIP) toward H2O2 have not been determined. This study investigates the H2O2-regulated expression levels of all plasma membrane aquaporins of Arabidopsis thaliana (AtPIPs), and determines the permeability of every AtPIP for H2O2 in yeast. Hydrogen peroxide treatment of Arabidopsis down-regulated the expression of AtPIP2 subfamily in roots but not in leaves, whereas the expression of AtPIP1 subfamily was not affected by H2O2 treatment. The growth and survival of yeast cells that expressed AtPIP2;2, AtPIP2;4, AtPIP2;5, or AtPIP2;7 was reduced in the presence of H2O2, while the growth of yeast cells expressing any other AtPIP family member was not affected by H2O2. These results show that only certain isoforms of AtPIPs whose expression is regulated by H2O2 treatment are permeable for H2O2 in yeast cells, and suggest that the integrated regulation of aquaporin expression by H2O2 and the capacity of individual aquaporin to transport H2O2 are important for plant response to H2O2.