sas1, an Arabidopsis mutant overaccumulating sodium in the shoot, shows deficiency in the control of the root radial transport of sodium |
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| Authors: | Nublat A Desplans J Casse F Berthomieu P |
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| Affiliation: | Unité Mixte de Recherche 5004, Ecole National Supérieure Agronomique de Montpellier, Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, Université Montpellier II, Montpellier, France. |
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| Abstract: | A recessive mutation of Arabidopsis designated sas1 (for sodium overaccumulation in shoot) that was mapped to the bottom of chromosome III resulted in a two- to sevenfold overaccumulation of Na(+) in shoots compared with wild-type plants. sas1 is a pleiotropic mutation that also caused severe growth reduction. The impact of NaCl stress on growth was similar for sas1 and wild-type plants; however, with regard to survival, sas1 plants displayed increased sensitivity to NaCl and LiCl treatments compared with wild-type plants. sas1 mutants overaccumulated Na(+) and its toxic structural analog Li(+), but not K(+), Mg(2)+, or Ca(2)+. Sodium accumulated preferentially over K(+) in a similar manner for sas1 and wild-type plants. Sodium overaccumulation occurred in all of the aerial organs of intact sas1 plants but not in roots. Sodium-treated leaf fragments or calli displayed similar Na(+) accumulation levels for sas1 and wild-type tissues. This suggested that the sas1 mutation impaired Na(+) long-distance transport from roots to shoots. The transpiration stream was similar in sas1 and wild-type plants, whereas the Na(+) concentration in the xylem sap of sas1 plants was 5.5-fold higher than that of wild-type plants. These results suggest that the sas1 mutation disrupts control of the radial transport of Na(+) from the soil solution to the xylem vessels. |
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