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Disruption of AtMRP4 , a guard cell plasma membrane ABCC‐type ABC transporter, leads to deregulation of stomatal opening and increased drought susceptibility
Author(s) -
Klein Markus,
Geisler Markus,
Suh Su Jeoung,
Kolukisaoglu H. Üner,
Azevedo Louis,
Plaza Sonia,
Curtis Mark D.,
Richter Andreas,
Weder Barbara,
Schulz Burkhard,
Martinoia Enrico
Publication year - 2004
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2004.02125.x
Subject(s) - guard cell , atp binding cassette transporter , cystic fibrosis transmembrane conductance regulator , mutant , microbiology and biotechnology , biology , wild type , biochemistry , sulfonylurea receptor , transport protein , transporter , gene , protein subunit
Summary ATP‐binding cassette (ABC) transporters are membrane proteins responsible for cellular detoxification processes in plants and animals. Recent evidence shows that this class of transporters may also be involved in many other cellular processes. Because of their homology with human multidrug resistance‐associated proteins (MRP), cystic fibrosis transmembrane conductance regulator (CFTR) and sulfonylurea receptor (SUR), some plant ABC transporters have been implicated in the regulation of ion channel activities. This paper describes an investigation of the AtMRP4 gene and its role in stomatal regulation. Reporter gene studies showed that AtMRP4 is highly expressed in stomata and that the protein is localized to the plasma membrane. Stomatal aperture in three independent atmrp4 mutant alleles was larger than in wild‐type plants, both in the light and in the dark, resulting in increased water loss but no change in the photosynthetic rate. In baker's yeast, AtMRP4 shows ATP‐dependent, vanadate‐sensitive transport of methotrexate (MTX), an antifolate and a substrate of mammalian MRPs. Treatment with MTX reduced stomatal opening in wild‐type plants, but had no effect in atmrp4 mutants. These results indicate the involvement of AtMRP4 in the complex regulation of stomatal aperture.