Organellar gene transcription and early seedling development are affected in the rpoT;2 mutant of Arabidopsis

Plant J. 2004 Apr;38(1):38-48. doi: 10.1111/j.1365-313X.2004.02022.x.


An Arabidopsis mutant that exhibited reduced root length was isolated from a population of activation-tagged T-DNA insertion lines in a screen for aberrant root growth. This mutant also exhibited reduced hypocotyl length as well as a delay in greening and altered leaf shape. Molecular genetic analysis of the mutant indicated a single T-DNA insertion in the gene RpoT;2 encoding a homolog of the phage-type RNA polymerase (RNAP), that is targeted to both mitochondria and plastids. A second T-DNA-tagged allele also showed a similar phenotype. The mutation in RpoT;2 affected the light-induced accumulation of several plastid mRNAs and proteins and resulted in a lower photosynthetic efficiency. In contrast to the alterations in the plastid gene expression, no major effect of the rpoT;2 mutation on the accumulation of examined mitochondrial gene transcripts and proteins was observed. The rpoT;2 mutant exhibited tissue-specific alterations in the transcript levels of two other organelle-directed nuclear-encoded RNAPs, RpoT;1 and RpoT;3. This suggests the existence of cross-talk between the regulatory pathways of the three RNAPs through organelle to nucleus communication. These data provide an important information on a role of RpoT;2 in plastid gene expression and early plant development.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics*
  • Arabidopsis / growth & development*
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / metabolism
  • Base Sequence
  • DNA Transposable Elements / genetics
  • DNA, Bacterial / genetics
  • DNA, Plant / genetics
  • DNA-Directed RNA Polymerases / genetics
  • Gene Expression Regulation, Developmental
  • Gene Expression Regulation, Plant
  • Genes, Plant
  • Mitochondria / genetics
  • Mutagenesis, Insertional
  • Mutation
  • Organelles / genetics
  • Photosystem II Protein Complex / metabolism
  • Plastids / genetics
  • Seedlings / growth & development


  • Arabidopsis Proteins
  • DNA Transposable Elements
  • DNA, Bacterial
  • DNA, Plant
  • Photosystem II Protein Complex
  • T-DNA
  • DNA-Directed RNA Polymerases