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Genetics Section

Wolf, Paul G. [2], Rowe, Carol A. [2], Hasebe, Mitsuyasu [1].

RNA editing in a fern chloroplast genome.

We sequenced transcripts from all putative genes for proteins, rRNAs, and a selection of those encoding tRNAs in the chloroplast genome of the fern Adiantum capillus-veneris. We detected 349 RNA editing sites when the cDNA sequence was compared to that of the genomic DNA. Of these sites, 10% were U-to-C edits and 90% were C-to-U edits. RNA editing created 19 new start codons, three new stop codons, and "repaired" 26 internal stop codons. Of the 330 editing sites that altered a codon, 26.1% were in the first codon position, 67.8% in the second and 6.1% in the third. We also detected 21 silent edits as well as 19 edits that were in untranslated regions, including introns and the anticodon of tRNALeu. The latter edit provided a tRNA that is not otherwise encoded in this genome and accounts for a heavily used leucine codon. The level of RNA editing in this fern is more than ten times that of any other vascular plant examined across an entire chloroplast genome. A previous study found even higher levels of editing in a hornwort (942 sites). This suggests that the relatively low levels of editing in seed plants (less than 0.05%) may not be typical for land plants, and that RNA editing may play a major role in chloroplast genome processing. Additionally, we found that 53 editing sites in Adiantum are homologous to editing sites in the hornwort, and some other land plants. This implies that a major component of RNA editing sites have been conserved for hundreds of millions of years.


1 - Institute for Basic Biology, Okazaki, 444-8585, Japan
2 - Utah State University, Department of Biology, College of Science, 5305 Old Main Hill, Logan, Utah, 84322-0305, United States

Keywords:
ferns
organelle
plant
Evolution
transcription
intron.

Presentation Type: Paper
Session: 53-4
Location: Peruvian (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 1:45 PM
Abstract ID:149


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