title: Mutation of the cytosolic ribosomal protein-encoding RPS10B gene affects shoot meristematic function in Arabidopsis.
abstract: BACKGROUND
  Plant cytosolic ribosomal proteins are encoded by small gene families. Mutants affecting these genes are often viable, but show growth and developmental defects, suggesting incomplete functional redundancy within the families. Dormancy to growth transitions, such as the activation of axillary buds in the shoot, are characterised by co-ordinated upregulation of ribosomal protein genes.
  
  
  RESULTS
  A recessive mutation in RPS10B, one of three Arabidopsis genes encoding the eukaryote-specific cytoplasmic ribosomal protein S10e, was found to suppress the excessive shoot branching mutant max2-1. rps10b-1 mildly affects the formation and separation of shoot lateral organs, including the shoot axillary meristems. Axillary meristem defects are enhanced when rps10b-1 is combined with mutations in REVOLUTA, AUXIN-RESISTANT1, PINOID or another suppressor of max2-1, FAR-RED ELONGATED HYPOCOTYL3. In some of these double mutants, the maintenance of the primary shoot meristem is also affected. In contrast, mutation of ALTERED MERISTEM PROGRAMME1 suppresses the rps10b-1axillary shoot defect. Defects in both axillary shoot formation and organ separation were enhanced by combining rps10b-1 with cuc3, a mutation affecting one of three Arabidopsis NAC transcription factor genes with partially redundant roles in these processes. To assess the effect of rps10b-1 on bud activation independently from bud formation, axillary bud outgrowth on excised cauline nodes was analysed. The outgrowth rate of untreated buds was reduced only slightly by rps10b-1 in both wild-type and max2-1 backgrounds. However, rps10b-1 strongly suppressed the auxin resistant outgrowth of max2-1 buds. A developmental phenotype of rps10b-1, reduced stamen number, was complemented by the cDNA of another family member, RPS10C, under the RPS10B promoter.
  
  
  CONCLUSIONS
  RPS10B promotes shoot branching mainly by promoting axillary shoot development. It contributes to organ boundary formation and leaf polarity, and sustains max2-1 bud outgrowth in the presence of auxin. These processes require the auxin response machinery and precise spatial distribution of auxin. The correct dosage of protein(s) involved in auxin-mediated patterning may be RPS10B-dependent. Inability of other RPS10 gene family members to maintain fully S10e levels might cause the rps10b-1 phenotype, as we found no evidence for unique functional specialisation of either RPS10B promoter or RPS10B protein.
authors.affiliation: Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK.
authors.forename: Petra
authors.initials: P
authors.lastname: Stirnberg
authors.forename: Jin-Ping
authors.initials: JP
authors.lastname: Liu
authors.forename: Sally
authors.initials: S
authors.lastname: Ward
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Kendall
authors.forename: Ottoline
authors.initials: O
authors.lastname: Leyser
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D044783:F-Box Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D007210:Indoleacetic Acids / Q000378:metabolism / Q000494:pharmacology; D056626:Inflorescence / Q000235:genetics / Q000378:metabolism; D018519:Meristem / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009280:Naphthaleneacetic Acids / Q000494:pharmacology; D010641:Phenotype; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D011401:Promoter Regions, Genetic; D025941:Protein Interaction Mapping; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D012269:Ribosomal Proteins / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C478975:CUC3 protein, Arabidopsis; D018076:DNA, Complementary; D044783:F-Box Proteins; D007210:Indoleacetic Acids; D009280:Naphthaleneacetic Acids; D011956:Receptors, Cell Surface; D012269:Ribosomal Proteins; C540796:Rps10 protein, Arabidopsis; C501405:TIR1 protein, Arabidopsis; D014157:Transcription Factors; C034182:1-naphthaleneacetic acid