title: Nuclear ribosome biogenesis mediated by the DIM1A rRNA dimethylase is required for organized root growth and epidermal patterning in Arabidopsis.
abstract: Position-dependent patterning of hair and non-hair cells in the Arabidopsis thaliana root epidermis is a powerful system to study the molecular basis of cell fate specification. Here, we report an epidermal patterning mutant affecting the ADENOSINE DIMETHYL TRANSFERASE 1A (DIM1A) rRNA dimethylase gene, predicted to participate in rRNA posttranscriptional processing and base modification. Consistent with a role in ribosome biogenesis, DIM1A is preferentially expressed in regions of rapid growth, and its product is nuclear localized with nucleolus enrichment. Furthermore, DIM1A preferentially accumulates in the developing hair cells, and the dim1A point mutant alters the cell-specific expression of the transcriptional regulators GLABRA2, CAPRICE, and WEREWOLF. Together, these findings suggest that establishment of cell-specific gene expression during root epidermis development is dependent upon proper ribosome biogenesis, possibly due to the sensitivity of the cell fate decision to relatively small differences in gene regulatory activities. Consistent with its effect on the predicted S-adenosyl-l-Met binding site, dim1A plants lack the two 18S rRNA base modifications but exhibit normal pre-rRNA processing. In addition to root epidermal defects, the dim1A mutant exhibits abnormal root meristem division, leaf development, and trichome branching. Together, these findings provide new insights into the importance of rRNA base modifications and translation regulation for plant growth and development.
authors: Department of Molecular, Cellular, and Developmental Biology, University of Michigan, An Arbor, MI 48105, USA.
authors: Yana
authors: Y
authors: Wieckowski
authors: John
authors: J
authors: Schiefelbein
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D019521:Body Patterning; D002467:Cell Nucleus / Q000378:metabolism; D018548:Cotyledon / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D018519:Meristem / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009928:Organ Specificity; D035261:Plant Components, Aerial / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D019441:Plant Epidermis / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*; D018517:Plant Roots / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*; D030821:Plants, Genetically Modified; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D016415:Sequence Alignment
chemical_list: D029681:Arabidopsis Proteins; D018749:RNA, Plant; D012335:RNA, Ribosomal; C578307:DIM1A protein, Arabidopsis; D008780:Methyltransferases; C047346:16S rRNA (adenine(1518)-N(6)-adenine(1519)-N(6))-dimethyltransferase