Theoretical and Applied Genetics

, Volume 117, Issue 3, pp 459–470

The mitochondrial genome of a cytoplasmic male sterile line of perennial ryegrass (Lolium perenne L.) contains an integrated linear plasmid-like element

  • Paul McDermott
  • Vincent Connolly
  • Tony A. Kavanagh
Original Paper

DOI: 10.1007/s00122-008-0790-7

Cite this article as:
McDermott, P., Connolly, V. & Kavanagh, T.A. Theor Appl Genet (2008) 117: 459. doi:10.1007/s00122-008-0790-7

Abstract

The mitochondrial genome of a cytoplasmic male sterile line of perennial ryegrass (Lolium perenne L.) was shown to contain a 9.6 kb element, LpCMSi, that is absent in the mitochondrial genome of fertile lines. LpCMSi contains the previously described chimeric gene orfC9, and three additional open reading frames (orfs) encoding a unique 45 kDa predicted protein of unknown function, a family B-like DNA polymerase (LpDpo), and a phage-type single subunit RNA polymerase (LpRpo). The latter two proteins shared significant similarity with DNA and RNA polymerases encoded by extrachromosomal linear mitochondrial plasmids of plants and fungi, and also to integrated plasmid-like sequences found in various plant and fungal mitochondrial genomes. Transcripts for both LpDpo and LpRpo were detected by RT-PCR in mitochondria of the CMS line. PCR-based investigations further revealed the presence of LpCMSi-like sequences in fertile L. perenne lines that are likely maintained as low-copy number extrachromosomal replicons. The absence of integrated forms of LpCMSi in the mitochondrial genome of fertile lines suggests that LpCMSi integration adjacent to the atp9 gene may be responsible, directly or indirectly, for the sterility phenotype of the CMS line.

Supplementary material

122_2008_790_MOESM1_ESM.doc (87 kb)
Supplementary Table 1: Synonymous and non-synonymous nucleotide substitutions in the sequenced Dpo genes. The amino acid differences resulting from non-synonymous substitutions (relative to LpRpo) are indicated in the single letter format beside the relevant codon. (DOC 87 kb)
122_2008_790_MOESM2_ESM.doc (145 kb)
Supplementary Table 2: Synonymous and non-synonymous nucleotide substitutions in the sequenced Rpo genes. The amino acid differences resulting from non-synonymous substitutions (relative to LpRpo) are indicated in the single letter format beside the relevant codon. (DOC 145 kb)

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Paul McDermott
    • 1
  • Vincent Connolly
    • 1
    • 2
  • Tony A. Kavanagh
    • 1
  1. 1.Plant Molecular Genetics Laboratory, Smurfit Institute of GeneticsTrinity CollegeDublin 2Ireland
  2. 2.Teagasc, Oakpark Research CentreCarlowIreland

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