Plant biology: The usual channels

Soil waterlogging can be a big problem for farmers and growers, causing plant roots to suffer acute oxygen deprivation (anoxia). An early response of plants to anoxia is to shut down the water channels or aquaporins in the plasma membrane of root cells. Now the mechanism by which this channel shutdown occurs has been identified, providing clues as to how flood-tolerant crops may be bred or engineered. Anoxic stress is accompanied by acidification of the cytosol in root cells, which in turn blocks water transport mediated by the aquaporins of PIP, the plasma membrane intrinsic protein. Mutant aquaporins have altered sensitivity to cytosolic pH, and these mutants may be useful in testing the assumption that aquaporin activity in plant roots can be detrimental under stress.

Cytosolic pH regulates root water transport during anoxic stress through gating of aquaporins
COLETTE TOURNAIRE-ROUX, MOIRA SUTKA, HÉLÈNE JAVOT, ELISABETH GOUT, PATRICIA GERBEAU, DOAN-TRUNG LUU, RICHARD BLIGNY & CHRISTOPHE MAUREL
Nature 425, 393–397 (2003); doi:10.1038/nature01853
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Plant biology: Water gate
N. MICHELE HOLBROOK & MACIEJ A. ZWIENIECKI
Flooding reduces the ability of roots to absorb water. The molecular basis for this paradox involves the regulation of water-channel proteins by the pH inside root cells.
Nature 425, 361 (2003); doi:10.1038/425361a
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