title: Expression of EuNOD-ARP1 encoding auxin-repressed protein homolog is upregulated by auxin and localized to the fixation zone in root nodules of Elaeagnus umbellata.
abstract: Root nodule formation is controlled by plant hormones such as auxin. Auxin-repressed protein (ARP) genes have been identified in various plant species but their functions are not clear. We have isolated a full-length cDNA clone (EuNOD-ARP1) showing high sequence homology to previously identified ARP genes from root nodules of Elaeagnus umbellata. Genomic Southern hybridization showed that there are at least four ARP-related genes in the genome of E. umbellata. The cDNA clone encodes a polypeptide of 120 amino acid residues with no signal peptide or organelle-targeting signals, indicating that it is a cytosolic protein. Its cytosolic location was confirmed using Arabidopsis protoplasts expressing a EuNOD-ARP1:smGFP fusion protein. Northern hybridization showed that EuNOD-ARP1 expression was higher in root nodules than in leaves or uninoculated roots. Unlike the ARP genes of strawberry and black locust, which are negatively regulated by exogenous auxin, EuNOD-ARP1 expression is induced by auxin in leaf tissue of E. umbellata. In situ hybridization revealed that EuNOD-ARP1 is mainly expressed in the fixation zone of root nodules.
authors.affiliation: School of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul 151-747, Korea. hobang@snu.ac.kr
authors.forename: Ho Bang
authors.initials: HB
authors.lastname: Kim
authors.forename: Hyoungseok
authors.initials: H
authors.lastname: Lee
authors.forename: Chang Jae
authors.initials: CJ
authors.lastname: Oh
authors.forename: Nam Houn
authors.initials: NH
authors.lastname: Lee
authors.forename: Chung Sun
authors.initials: CS
authors.lastname: An
mesh_terms: D000595:Amino Acid Sequence; D015139:Blotting, Southern; D031263:Elaeagnaceae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D018745:Genome, Plant / Q000187:drug effects; D007210:Indoleacetic Acids / Q000494:pharmacology*; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D021381:Protein Transport / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D053204:Root Nodules, Plant / Q000166:cytology / Q000187:drug effects*; D017386:Sequence Homology, Amino Acid; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D007210:Indoleacetic Acids; D010940:Plant Proteins; D012333:RNA, Messenger