Plant aquaporins: regulation and role in roots, seeds and leaves

MAUREL C, SANTONI V, POSTAIRE O, BOURSIAC C, LUU D T, TOURNAIRE-ROUX C, PRAK S, SORIEUL M AND SUTKA M.

Nara, Japón.

Congreso; 5th International Conference of Aquaporin; 2007

Comite organizadora ad hoc

  A combination of pharmacological and reverse genetic approches was developed in Arabidopsis to show that aquaporins are crucial for plant water relations and contribute to water transport throughout the whole plant body. In particular, transgenic plants that over-express or are disrupted in a single aquaporin gene were used to dissect the role of individual plasma membrane aquaporin isoforms in roots and inner leaf tissues. Roots were also used as a model system to investigate the variety of cellular and molecular mechanisms that can account for plant aquaporin regulation, Proteomic analyses revealed that plasma membrane aquaporins carry multiple post-translational modifications including phosphorylation and methylation. Exposure of roots to salt induces aquaporins dephosphorylation, and changes in aquaporin expression and subcellular localization at multiple levels, which may act in concert to regulate root water transport. By contrast, inhibition of root water uptake by anoxia is linked to cytosol acidosis, which inhibits all plasma membrane aquaporins by a direct gating mechanism. Hydrogen peroxide (H2O2) and/or derived reactive oxygen species, which accumulate in roots under stress, also act as a potent inhibitor of water transport in Arabidopsis roots. We will show that H2O2 does not regulate water transport by gating aquaporins through a direct oxidation mechanism. By contrast, H2O2 acts on calcium signalling cascades and on a membrane internalisation mechanism which down-regulate plasma membrane aquaporin function.