title: Transcriptional downregulation of rice rpL32 gene under abiotic stress is associated with removal of transcription factors within the promoter region.
abstract: BACKGROUND
  The regulation of ribosomal proteins in plants under stress conditions has not been well studied. Although a few reports have shown stress-specific post-transcriptional and translational mechanisms involved in downregulation of ribosomal proteins yet stress-responsive transcriptional regulation of ribosomal proteins is largely unknown in plants.
  
  
  RESULTS
  In the present work, transcriptional regulation of genes encoding rice 60S ribosomal protein L32 (rpL32) in response to salt stress has been studied. Northern and RT-PCR analyses showed a significant downregulation of rpL32 transcripts under abiotic stress conditions in rice. Of the four rpL32 genes in rice genome, the gene on chromosome 8 (rpL32_8.1) showed a higher degree of stress-responsive downregulation in salt sensitive rice variety than in tolerant one and its expression reverted to its original level upon withdrawal of stress. The nuclear run-on and promoter:reporter assays revealed that the downregulation of this gene is transcriptional and originates within the promoter region. Using in vivo footprinting and electrophoretic mobility shift assay (EMSA), cis-elements in the promoter of rpL32_8.1 showing reduced binding to proteins in shoots of salt stressed rice seedlings were identified.
  
  
  CONCLUSIONS
  The present work is one of the few reports on study of stress downregulated genes. The data revealed that rpL32 gene is transcriptionally downregulated under abiotic stress in rice and that this transcriptional downregulation is associated with the removal of transcription factors from specific promoter elements.
authors: Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, Delhi, India.
authors: Pradipto
authors: P
authors: Mukhopadhyay
authors: Malireddy K
authors: MK
authors: Reddy
authors: Sneh Lata
authors: SL
authors: Singla-Pareek
authors: Sudhir K
authors: SK
authors: Sopory
mesh_terms: D001483:Base Sequence; D015152:Blotting, Northern; D002457:Cell Extracts; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D032461:Chromosomes, Plant / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics*; D024202:Electrophoretic Mobility Shift Assay; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D008969:Molecular Sequence Data; D012275:Oryza / Q000187:drug effects / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000235:genetics; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism*; D024363:Transcription Initiation Site; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D002457:Cell Extracts; D010940:Plant Proteins; D012269:Ribosomal Proteins; D014157:Transcription Factors; C041806:ribosomal protein L32; D012965:Sodium Chloride