Function, intracellular localization and the importance in salt tolerance of a vacuolar Na(+)/H(+) antiporter from rice.
We examined the function and intracellular localization of the product of the Na(+)/H(+) antiporter gene (OsNHX1) cloned from rice (Oryza sativa). OsNHX1 has the ability to suppress Na(+), Li(+) and hygromycin sensitivity of yeast nhx1 mutants and sensitivity to a high K(+) concentration, a novel phenotype of the nhx1 mutants. Analysis using rice cells expressing a fusion protein of OsNHX1 and green fluorescent protein and Western blot analysis using antibodies specific for OsNHX1 confirmed the localization of OsNHX1 on the tonoplasts. These results indicate that the OsNHX1 gene encodes a vacuolar (Na(+), K(+))/H(+) antiporter. Treatment with high concentrations of NaCl and KCl increased the transcript levels of OsNHX1 in rice roots and shoots. In addition, overexpression of OsNHX1 improved the salt tolerance of transgenic rice cells and plants. These results suggest that OsNHX1 on the tonoplasts plays important roles in the compartmentation of Na(+) and K(+) highly accumulated in the cytoplasm into the vacuoles, and the amount of the antiporter is one of the most important factors determining salt tolerance in rice.
National Institute of Agrobiological Sciences, Kannondai 2-1-2, Tsukuba, Ibaraki, 305-8602 Japan. fukuda@affrc.go.jp
Atsunori
A
Fukuda
Atsuko
A
Nakamura
Akemi
A
Tagiri
Hiroshi
H
Tanaka
Akio
A
Miyao
Hirohiko
H
Hirochika
Yoshiyuki
Y
Tanaka
D027682:Cation Transport Proteins / Q000235:genetics* / Q000378:metabolism*; D002451:Cell Compartmentation / Q000235:genetics*; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000235:genetics; D012275:Oryza / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012492:Salts / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics* / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D014617:Vacuoles / Q000378:metabolism*
D027682:Cation Transport Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D012492:Salts; D017923:Sodium-Hydrogen Exchangers; D012965:Sodium Chloride; D011189:Potassium Chloride