title: ACAULIS5, an Arabidopsis gene required for stem elongation, encodes a spermine synthase.
abstract: Polyamines have been implicated in a wide range of biological processes, including growth and development in bacteria and animals, but their function in higher plants is unclear. Here we show that the Arabidopsis: ACAULIS5 (ACL5) gene, whose inactivation causes a defect in the elongation of stem internodes by reducing cell expansion, encodes a protein that shares sequence similarity with the polyamine biosynthetic enzymes spermidine synthase and spermine synthase. Expression of the recombinant ACL5 protein in Escherichia coli showed that ACL5 possesses spermine synthase activity. Restoration of the acl5 mutant phenotype by somatic reversion of a transposon-induced allele suggests a non-cell-autonomous function for the ACL5 gene product. We also found that expression of the ACL5 cDNA under the control of a heat shock gene promoter in acl5 mutant plants restores the phenotype in a heat shock-dependent manner. The results of the experiments showed that polyamines play an essential role in promotion of internode elongation through cell expansion in Arabidopsis: We discuss the relationships to plant growth regulators such as auxin and gibberellins that have related functions.
authors.affiliation: Division of Biological Sciences, Graduate School of Science, Hokkaido University, N10, W8, Sapporo 060-0810, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Hanzawa
authors.forename: T
authors.initials: T
authors.lastname: Takahashi
authors.forename: A J
authors.initials: AJ
authors.lastname: Michael
authors.forename: D
authors.initials: D
authors.lastname: Burtin
authors.forename: D
authors.initials: D
authors.lastname: Long
authors.forename: M
authors.initials: M
authors.lastname: Pineiro
authors.forename: G
authors.initials: G
authors.lastname: Coupland
authors.forename: Y
authors.initials: Y
authors.lastname: Komeda
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins; D015152:Blotting, Northern; D003001:Cloning, Molecular; D004251:DNA Transposable Elements; D018076:DNA, Complementary / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics* / Q000502:physiology*; D011401:Promoter Regions, Genetic; D011700:Putrescine / Q000737:chemistry; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013095:Spermidine / Q000737:chemistry; D013096:Spermine / Q000737:chemistry; D013097:Spermine Synthase / Q000235:genetics* / Q000502:physiology*; D013997:Time Factors; D014018:Tissue Distribution; D019076:Transgenes
chemical_list: C414439:ACAULIS5 protein, Arabidopsis; D029681:Arabidopsis Proteins; D004251:DNA Transposable Elements; D018076:DNA, Complementary; D010940:Plant Proteins; D011994:Recombinant Proteins; D013096:Spermine; D013097:Spermine Synthase; D013095:Spermidine; D011700:Putrescine