title: NKS1, Na(+)- and K(+)-sensitive 1, regulates ion homeostasis in an SOS-independent pathway in Arabidopsis.
abstract: An Arabidopsis thaliana mutant, nks1-1, exhibiting enhanced sensitivity to NaCl was identified in a screen of a T-DNA insertion population in the genetic background of Col-0 gl1sos3-1. Analysis of the genome sequence in the region flanking the T-DNA left border indicated two closely linked mutations in the gene encoded at locus At4g30996. A second allele, nks1-2, was obtained from the Arabidopsis Biological Resource Center. NKS1 mRNA was detected in all parts of wild-type plants but was not detected in plants of either mutant, indicating inactivation by the mutations. Both mutations in NKS1 were associated with increased sensitivity to NaCl and KCl, but not to LiCl or mannitol. NaCl sensitivity was associated with nks1 mutations in Arabidopsis lines expressing either wild type or null alleles of SOS1, SOS2 or SOS3. The NaCl-sensitive phenotype of the nks1-2 mutant was complemented by expression of a full-length NKS1 allele from the CaMV35S promoter. When grown in medium containing NaCl, nks1 mutants accumulated more Na(+) than wild type and K(+)/Na(+) homeostasis was perturbed. It is proposed NKS1, a plant-specific gene encoding a 19kDa endomembrane-localized protein of unknown function, is part of an ion homeostasis regulation pathway that is independent of the SOS pathway.
authors.affiliation: Division of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Republic of Korea.
authors.forename: Wonkyun
authors.initials: W
authors.lastname: Choi
authors.forename: Dongwon
authors.initials: D
authors.lastname: Baek
authors.forename: Dong-Ha
authors.initials: DH
authors.lastname: Oh
authors.forename: Jiyoung
authors.initials: J
authors.lastname: Park
authors.forename: Hyewon
authors.initials: H
authors.lastname: Hong
authors.forename: Woe-Yeon
authors.initials: WY
authors.lastname: Kim
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Bohnert
authors.forename: Ray A
authors.initials: RA
authors.lastname: Bressan
authors.forename: Hyeong Cheol
authors.initials: HC
authors.lastname: Park
authors.forename: Dae-Jin
authors.initials: DJ
authors.lastname: Yun
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D004269:DNA, Bacterial / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000737:chemistry; D018506:Gene Expression Regulation, Plant; D049452:Green Fluorescent Proteins / Q000502:physiology; D006706:Homeostasis / Q000235:genetics / Q000502:physiology*; D008164:Luminescent Proteins / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D011188:Potassium / Q000032:analysis / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D012964:Sodium / Q000032:analysis / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological / Q000502:physiology; D000097573:Red Fluorescent Protein
chemical_list: D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D008565:Membrane Proteins; D011188:Potassium; D017346:Protein Serine-Threonine Kinases; D012964:Sodium; D017923:Sodium-Hydrogen Exchangers; D000097573:Red Fluorescent Protein; C558077:NKS1 protein, Arabidopsis; C477653:SOS1 protein, Arabidopsis; C112941:SOS3 protein, Arabidopsis; C036483:T-DNA; C406738:SOS2 protein, Arabidopsis