Hydrogen peroxide permeability of plasma membrane aquaporins of Arabidopsis thaliana

Although aquaporins have been known to transport hydrogen peroxide (H ₂O ₂) across cell membranes, the H ₂O ₂-regulated expression patterns and the permeability of every family member of the plasma membrane intrinsic protein (PIP) toward H ₂O ₂ have not been determined. This study investigates the H ₂O ₂-regulated expression levels of all plasma membrane aquaporins of Arabidopsis thaliana (AtPIPs), and determines the permeability of every AtPIP for H ₂O ₂ 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 H ₂O ₂ 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 H ₂O ₂, while the growth of yeast cells expressing any other AtPIP family member was not affected by H ₂O ₂. These results show that only certain isoforms of AtPIPs whose expression is regulated by H ₂O ₂ treatment are permeable for H ₂O ₂ in yeast cells, and suggest that the integrated regulation of aquaporin expression by H ₂O ₂ and the capacity of individual aquaporin to transport H ₂O ₂ are important for plant response to H ₂O ₂.