title: A mutation in the Arabidopsis KT2/KUP2 potassium transporter gene affects shoot cell expansion.
abstract: Potassium ions (K(+)) are the most abundant cations in plants and are necessary for cell growth. Arabidopsis shy3-1 mutant plants have a short hypocotyl, small leaves, and a short flowering stem, and these defects result from decreased cell expansion. The semidominant shy3-1 mutation changes an amino acid in KT2/KUP2, a K(+) transporter related to the Escherichia coli Kup protein. Second mutations in the KT2/KUP2/SHY3 gene, including presumed null mutations, suppress the shy3-1 phenotypes. Plants with these intragenic suppressor mutations appear similar to wild-type plants, suggesting that KT2/KUP2/SHY3 acts redundantly with other genes. Expression of the shy3-1 mutant version of KT2/KUP2/SHY3 in wild-type plants confers shy3-1-like phenotypes, indicating that shy3-1 probably either causes a gain of function or creates an interfering protein. The shy3-1 mutation does not eliminate the ability of the KT2/KUP2 cDNA to rescue the growth of a potassium transport-deficient E. coli mutant. A P(SHY3)::GUS fusion is expressed in growing portions of the plant. These results suggest that KT2/KUP2/SHY3 mediates K(+)-dependent cell expansion in growing tissues.
authors.affiliation: Department of Biology, University of North Carolina at Chapel Hill, Coker Hall, Chapel Hill, NC 27599-3280, USA.
authors.forename: Rangasamy P
authors.initials: RP
authors.lastname: Elumalai
authors.forename: Punita
authors.initials: P
authors.lastname: Nagpal
authors.forename: Jason W
authors.initials: JW
authors.lastname: Reed
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics*; D001692:Biological Transport / Q000235:genetics; D002455:Cell Division / Q000187:drug effects; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D005786:Gene Expression Regulation; D005816:Genetic Complementation Test; D005838:Genotype; D018546:Hypocotyl / Q000235:genetics / Q000254:growth & development; D017136:Ion Transport / Q000235:genetics; D009154:Mutation; D010641:Phenotype; D018520:Plant Shoots / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified; D011188:Potassium / Q000378:metabolism*; D012413:Rubidium / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D012413:Rubidium; D011188:Potassium