| Abstract Detail
Organelle Biology Wahrmund, Ute [1], Ruedinger, Mareike [2], Polsakiewicz, Monika [3], Groth-Malonek, Milena [3], Knoop, Volker [4]. Extremely long survival of a pseudogene and the mystery of RNA editing in liverwort mitochondria. The nad7 gene is functionally encoded in the mitochondrial DNA of the plant lineage but is a pseudogene in the liverwort Marchantia polymorpha where the functional gene copy is encoded in the nucleus. We now found that a mitochondrial nad7 pseudogene is a universal feature of marchantiid and jungermanniid liverwort mtDNA across a wide phylogenetic sampling, which indicates a very ancient functional gene transfer before the separation of the two subclasses of this old plant clade and a surprisingly long survival of the pseudogene copy in the mitochondria, maybe exceeding 400 mio. ys. Strikingly though, nad7 is an intact mitochondrial gene in the liverwort genera Treubia and Haplomitrium strongly confirming their phylogenetic re-placement basal to the marchantiid-jungermanniid dichotomy on the basis of recent molecular data. Transcripts of plant organelle genes are modified through the exchange of cytidines and uridines and this RNA editing process has been identified in all land plant clades except the marchantiid (complex-thalloid) liverworts. Like other mitochondrial transcripts the nad7 mRNA is heavily edited in Haplomitrium, clearly supporting a secondary loss of RNA editing in the marchantiids. A large gene family of mostly organelle-targeted RNA-binding proteins was recently identified in Arabidopsis and rice. These PPR (pentatricopeptide repeat) proteins are excellent candidates to provide specificities of editing site recognition. We focussed on a plant-specific subclade of extended PPR protein genes and found a perfect correlation between their presence as detected on genomic and transcript level and the occurrence of RNA editing.
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1 - University of Bonn, Bonn, Germany
2 - IZMB - Inst. f. Zellulare und Molekulare Botanik, Bonn University, Molekulare Evolution
3 - IZMB - Inst. f. Zellulare u. Molekulare Botanik, Bonn University, Molekulare Evolution
4 - IZMB - Inst. f. Zellulare u. Molekulare Botanik, Bonn University, Molekulare Evolution, Kirschallee 1, Bonn, D-53115, Germany
Keywords:
mitochondria
RNA editing
liverworts
phylogenetics.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P18021
Abstract ID:1329 |
