PAUSED, a putative exportin-t, acts pleiotropically in Arabidopsis development but is dispensable for viability.
Exportin-t was first identified in humans as a protein that mediates the export of tRNAs from the nucleus to the cytoplasm. Mutations in Los1p, the Saccharomyces cerevisiae exportin-t homolog, result in nuclear accumulation of tRNAs. Because no exportin-t mutants have been reported in multicellular organisms, the developmental functions of exportin-t have not been determined. Here, we report the isolation and characterization of two Arabidopsis exportin-t mutants, paused-5 and paused-6. The mutant phenotypes indicate that exportin-t acts pleiotropically in plant development. In particular, paused-5 and paused-6 result in delayed leaf formation during vegetative development. The two paused mutations also cause the transformation of reproductive organs into perianth organs in the hua1-1 hua2-1 background, which is partially defective in reproductive organ identity specification. The floral phenotypes of hua1-1 hua2-1 paused mutants resemble those of mutations in the floral homeotic gene AGAMOUS. Moreover, paused-5 enhances the mutant phenotypes of two floral meristem identity genes, LEAFY and APETALA1. The developmental defects caused by paused mutations confirm the important roles of exportin-t in gene expression in multicellular organisms. In addition, a paused null allele, paused-6, is still viable, suggesting the presence of redundant tRNA export pathway(s) in Arabidopsis.
Li
Junjie
J
Waksman Institute, Rutgers University, Piscataway, New Jersey 08854, USA.
Chen
Xuemei
X
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D035264:Flowers / Q000235:genetics / Q000254:growth & development; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D006801:Humans; D028884:Karyopherins / Q000235:genetics / Q000378:metabolism*; D018519:Meristem / Q000235:genetics / Q000254:growth & development; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D012343:RNA, Transfer / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C445095:HUA1 protein, Arabidopsis; C118465:HUA2 protein, Arabidopsis; D028884:Karyopherins; D018749:RNA, Plant; D016601:RNA-Binding Proteins; D014157:Transcription Factors; C478025:paused protein, Arabidopsis; D012343:RNA, Transfer