Showing papers by "Eduardo Blumwald published in 1999"

Salt Tolerance Conferred by Overexpression of a Vacuolar Na+/H+ Antiport in Arabidopsis

Abstract: Agricultural productivity is severely affected by soil salinity. One possible mechanism by which plants could survive salt stress is to compartmentalize sodium ions away from the cytosol. Overexpression of a vacuolar Na+/H+antiport from Arabidopsis thaliana in Arabidopsisplants promotes sustained growth and development in soil watered with up to 200 millimolar sodium chloride. This salinity tolerance was correlated with higher-than-normal levels of AtNHX1transcripts, protein, and vacuolar Na+/H+(sodium/proton) antiport activity. These results demonstrate the feasibility of engineering salt tolerance in plants.

Salt Tolerance and Crop Potential of Halophytes

Abstract: Although they represent only 2% of terrestrial plant species, halophytes are present in about half the higher plant families and represent a wide diversity of plant forms. Despite their polyphyletic origins, halophytes appear to have evolved the same basic method of osmotic adjustment: accumulation of inorganic salts, mainly NaCl, in the vacuole and accumulation of organic solutes in the cytoplasm. Differences between halophyte and gly-cophyte ion transport systems are becoming apparent. The pathways by which Na+ and Cl− enters halophyte cells are not well understood but may involve ion channels and pinocytosis, in addition to Na+ and Cl− transporters. Na+ uptake into vacuoles requires Na+/H+ antiporters in the tonoplast and H+ ATPases and perhaps PPi ases to provide the proton motive force. Tonoplast antiporters are constitutive in halophytes, whereas they must be activated by NaCl in salt-tolerant glycophytes, and they may be absent from salt-sensitive glycophytes. Halophyte vacuoles may have a modified...

Synthesis and oxidative insolubilization of cell-wall proteins during osmotic stress.

Abstract: The cell walls in the new white roots of jack pine (Pinus banksiana Lamb.) were observed to constrict around the shrinking protoplast of osmotically stressed roots, and pressure was maintained via an apparent adjustment of cell-wall size and elasticity. These elastic alterations of the cell wall permitted the root cells to maintain full turgor despite the loss of most of the water in the tissue. The constriction of the root cell wall around the dehydrating protoplasts to maintain turgor may reflect changes in cell wall structure. We found that these shrinking root cells synthesize and secrete into the intercellular fluid a set of proteins. These proteins become tightly associated (i.e. guanidine HCl- and sodium dodecyl sulfate-insoluble) with the cell wall but can be released from the matrix, after briefly boiling in 0.1% sodium dodecyl sulfate, by the combination of guanidine HCl, CaCl2 and dithiothreitol. However, these cell-wall proteins became insoluble with time. The proteins could subsequently be destructively extracted from the wall with acid NaClO2 treatments. After these proteins were incorporated into the cell walls, the roots adopted a new, smaller maximal tissue volume and elastic coefficients returned to normal levels.

Genetic engineering salt tolerance in crop plants

Abstract: The invention is isolated nucleic acid molecules encoding Na + /H + exchanger polypeptides with at least 95% homology to that of Arabidopsis thaliana for extrusion of monovalent cations from the cytosol of cells to provide the cell with increased salt tolerance. Crop species transformed with the nucleic acid molecule are capable of surviving in soil with high salt levels that would normally inhibit growth of the crop species.

Genie genetique de l'halotolerance dans les plantes cultivees

Abstract: La presente invention concerne des molecules isolees d'acides nucleiques qui codent pour des polypeptides echangeurs de Na+/H+. Ces polypeptides ont le pouvoir d'extraire des cations monovalents (de preference des ions lithium et potassium, mais surtout des ions sodium) du cytosol des cellules et conferent ainsi a la cellule une halotolerance accrue. Dans une realisation preferee, les molecules d'acides nucleiques sont obtenues a partir d'Arabidopsis thaliana. La transformation d'especes cultivees a l'aide des molecules d'acides nucleiques permet a ces especes de croitre dans des sols dont les concentrations elevees en sel devraient, normalement, inhiber leur croissance.