title: DCL is a plant-specific protein required for plastid ribosomal RNA processing and embryo development.
abstract: The defective chloroplast and leaf-mutable (dcl-m) mutation of tomato blocks chloroplast differentiation in leaf mesophyll cells and a signaling system that appears to be required for morphogenesis of palisade cells during leaf growth. To dissect the function of DCL, mutants with stable dcl alleles (dcl-s) were generated and examined for their phenotype. DCL/dcl-s plant produce dcl-s/dcl-s seeds with embryos arrested at the globular stage of development. The levels of several chloroplast- and nuclear-encoded proteins are strongly reduced in dcl-m mutant leaf sectors without significant changes in their corresponding mRNAs. The 4.5S rRNA fails to be processed efficiently, however, suggesting that DCL has a direct or indirect function in rRNA processing or correct ribosome assembly. Accordingly, chloroplasts in dcl-m sectors are impaired in polysome assembly, which can explain the reduced accumulation of chloroplast-encoded proteins. These results suggest that DCL is required for chloroplast rRNA processing, and emphasize the importance of plastid function during embryogenesis.
authors.affiliation: Institute of Plant Sciences, Swiss Federal Institute of Technology, Zurich, Switzerland. mohammed.bellaoui@utoronto.ca
authors.forename: Mohammed
authors.initials: M
authors.lastname: Bellaoui
authors.forename: James S
authors.initials: JS
authors.lastname: Keddie
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Gruissem
mesh_terms: D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000235:genetics; D002736:Chloroplasts / Q000378:metabolism; D018551:Solanum lycopersicum / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011132:Polyribosomes / Q000378:metabolism; D018747:RNA, Chloroplast / Q000378:metabolism*; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D012335:RNA, Ribosomal / Q000378:metabolism*; D012639:Seeds / Q000235:genetics / Q000254:growth & development*; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: C102165:DCL protein, Lycopersicon esculentum; D010940:Plant Proteins; D018747:RNA, Chloroplast; D018749:RNA, Plant; D012335:RNA, Ribosomal