Papers by Khaled Masmoudi
Plant Cell, 2006
Bookmarks Related papers MentionsView impact
Gene, 2007
Bookmarks Related papers MentionsView impact
Plant Cell Reports, 2007
Late Embryogenesis Abundant (LEA) proteins are associated with tolerance to water-related stress.... more Late Embryogenesis Abundant (LEA) proteins are associated with tolerance to water-related stress. A wheat (Triticum durum) group 2 LEA proteins, known also as dehydrin (DHN-5), has been previously shown to be induced by salt and abscisic acid (ABA). In this report, we analyze the effect of ectopic expression of Dhn-5 cDNA in Arabidopsis thaliana plants and their response to salt and osmotic stress. When compared to wild type plants, the Dhn-5 transgenic plants exhibited stronger growth under high concentrations of NaCl or under water deprivation, and showed a faster recovery from mannitol treatment. Leaf area and seed germination rate decreased much more in wild type than in transgenic plants subjected to salt stress. Moreover, the water potential was more negative in transgenic than in wild type plants. In addition, the transgenic plants have higher proline contents and lower water loss rate under water stress. Also, Na+ and K+ accumulate to higher contents in the leaves of the transgenic plants. Our data strongly support the hypothesis that Dhn-5, by its protective role, contributes to an improved tolerance to salt and drought stress through osmotic adjustment.
Bookmarks Related papers MentionsView impact
Plant Physiology and Biochemistry, 2001
Bookmarks Related papers MentionsView impact
Plant Molecular Biology, 2010
The regulation of plant signalling responses by Mitogen-Activated Protein Kinases (MAPKs)-mediate... more The regulation of plant signalling responses by Mitogen-Activated Protein Kinases (MAPKs)-mediated protein phosphorylation is well recognized. MAP kinase phosphatases (MKPs) are negative regulators of MAPKs in eukaryotes. We report here the identification and the characterization of TMKP1, the first wheat MKP (Triticum turgidum L. subsp. Durum). Expression profile analyses performed in two durum wheat cultivars showing a marked difference in salt and drought stress tolerance, revealed a differential regulation of TMKP1. Under salt and osmotic stress, TMKP1 is induced in the sensitive wheat variety and repressed in the tolerant one. A recombinant TMKP1 was shown to be an active phosphatase and capable to interact specifically with two wheat MAPKs (TMPK3 and TMPK6). In BY2 tobacco cells transiently expressing GFP::TMKP1, the fusion protein was localized into the nucleus. Interestingly, the deletion of the N-terminal non catalytic domain results in a strong accumulation of the truncated fusion protein in the cytoplasm. In addition, when expressed in BY2 cells, TMPK3 and TMPK6 fused to red fluorescent protein (RFP) were shown to be present predominantly in the nucleus. Surprisingly, when co-expressed with the N-terminal truncated TMKP1 fusion protein; both kinases are excluded from the nuclear compartment and accumulate in the cytoplasm. This strongly suggests that TMKP1 interacts in vivo with TMPK3 and TMPK6 and controls their subcellular localization. Taken together, our results show that the newly isolated wheat MKP might play an active role in modulating the plant cell responses to salt and osmotic stress responses.
Bookmarks Related papers MentionsView impact
Plant Physiology and Biochemistry, 2005
Bookmarks Related papers MentionsView impact
Acta Physiologiae Plantarum, 2009
Salinity is one of the severest environmental stresses affecting plant productivity. In many plan... more Salinity is one of the severest environmental stresses affecting plant productivity. In many plant species, salt sensitivity is associated with the accumulation of sodium (Na+) in photosynthetic tissues. Here, we provide the physiological and molecular analyses of seedlings of two Tunisian durum wheat genotypes (Triticum turgidum L. subsp. Durum [Desf.]), Mahmoudi (salt sensitive) and Om Rabia3 (salt tolerant). Na+ and K+ contents in leaf sheath from Om Rabia3 were significantly higher than those of Mahmoudi. However, the net uptake of Na+ from the soil occurred at similar rates in both varieties, suggesting that Om Rabia3 has much stronger ability to limit Na+ flux from roots to leaf blades. This mechanism could be explained by a capacity of Om Rabia3 to retain higher Na+ concentration in leaf sheath and unload less Na+ from the xylem to the upper shoots. When treated with 100 mM NaCl leaf sheaths of Om Rabia3 developed lower water potentials and a higher relative water contents than those of Mahmoudi. These features may arise from enhanced osmotic adjustment in Om Rabia3. Measurements of stomatal conductance, free proline and chlorophyll content also indicate that Om Rabia3 is better adapted to tolerate high salt than Mahmoudi. A correlation was obtained between the expression pattern of TaSOS1 (a plasma membrane Na+/H+ antiporter) in the roots and sheaths of both wheat varieties and the Na+ fluxes from roots to leaves. TaSOS1 transcript accumulated in Mahmoudi than in Om Rabia3, suggesting repression of TaSOS1 in the tolerant variety that reduces loading of Na+ to the upper shoots. These results help to design new genetic screens for salt tolerance in wheat.
Bookmarks Related papers MentionsView impact
Plant Science, 2007
Bookmarks Related papers MentionsView impact
Bioscience Biotechnology and Biochemistry, 2010
Bookmarks Related papers MentionsView impact
Journal of Experimental Botany, 2006
Bookmarks Related papers MentionsView impact
Uploads
Papers by Khaled Masmoudi