Reduced Na+ uptake in the NaCl-hypersensitive sos1 mutant of Arabidopsis thaliana.
Sos1 is an Arabidopsis thaliana mutant with > 20 times higher sensitivity toward Na+ inhibition due to a defective high-affinity potassium-uptake system. We report here that sos1 accumulates less Na+ than the wild type in response to NaCl stress. The Na+ contents in sos1 seedlings exposed to 25 mM NaCl for 2 or more d are about 43% lower than those in the wild type. When assayed at 20 mM external NaCl, sos1 seedlings pretreated with low potassium have 32% lower Na+ uptake than the wild type. However, little difference in Na+ uptake could be measured when the seedlings were not pretreated with low potassium. Low-potassium treatment was shown to induce high-affinity potassium-uptake activity in Arabidopsis seedlings. No substantial difference in Na+ efflux between sos1 and the wild type was detected. The results show that the reduced Na+ accumulation in sos1 is due to a lower Na+ influx rate. Therefore, the sos1 mutation appears to disrupt low-affinity Na+ uptake in addition to its impairment of high-affinity K+ uptake.
Ding
L
L
Department of Plant Sciences, University of Arizona, Tucson 85721, USA.
Zhu
J K
JK
D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D017343:Genes, Plant; D009154:Mutation; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology
D012965:Sodium Chloride; D012964:Sodium; D011188:Potassium