An enhancer mutant of Arabidopsis salt overly sensitive 3 mediates both ion homeostasis and the oxidative stress response.
The myristoylated calcium sensor SOS3 and its interacting protein kinase, SOS2, play critical regulatory roles in salt tolerance. Mutations in either of these proteins render Arabidopsis thaliana plants hypersensitive to salt stress. We report here the isolation and characterization of a mutant called enh1-1 that enhances the salt sensitivity of sos3-1 and also causes increased salt sensitivity by itself. ENH1 encodes a chloroplast-localized protein with a PDZ domain at the N-terminal region and a rubredoxin domain in the C-terminal part. Rubredoxins are known to be involved in the reduction of superoxide in some anaerobic bacteria. The enh1-1 mutation causes enhanced accumulation of reactive oxygen species (ROS), particularly under salt stress. ROS also accumulate to higher levels in sos2-1 but not in sos3-1 mutants. The enh1-1 mutation does not enhance sos2-1 phenotypes. Also, enh1-1 and sos2-1 mutants, but not sos3-1 mutants, show increased sensitivity to oxidative stress. These results indicate that ENH1 functions in the detoxification of reactive oxygen species resulting from salt stress by participating in a new salt tolerance pathway that may involve SOS2 but not SOS3.
Zhu
Jianhua
J
Horticulture and Landscape Architecture Department, Purdue University, West Lafayette, IN 47907, USA.
Fu
Xinmiao
X
Koo
Yoon Duck
YD
Zhu
Jian-Kang
JK
Jenney
Francis E
FE
Adams
Michael W W
MW
Zhu
Yanmei
Y
Shi
Huazhong
H
Yun
Dae-Jin
DJ
Hasegawa
Paul M
PM
Bressan
Ray A
RA
D000222:Adaptation, Physiological / Q000187:drug effects; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005816:Genetic Complementation Test; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006706:Homeostasis / Q000187:drug effects; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D018384:Oxidative Stress / Q000187:drug effects; D010641:Phenotype; D011188:Potassium / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012416:Rubredoxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012492:Salts / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology
D029681:Arabidopsis Proteins; C522128:ENH1 protein, Arabidopsis; D017382:Reactive Oxygen Species; D011993:Recombinant Fusion Proteins; D012416:Rubredoxins; C112941:SOS3 protein, Arabidopsis; D012492:Salts; D049452:Green Fluorescent Proteins; D012965:Sodium Chloride; C406738:SOS2 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases; D011188:Potassium; D002118:Calcium