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Abstract Detail

Genetics Section

Cahoon , Aubrey Bruce [1], Grimes, Bejamin [2], Sisay, Awa [3], Carroll, Hyrum [3].

Deep sequencing of the tobacco mitochondrial transcriptome reveals extensive processing, expressed ORFs, and numerous editing sites outside coding regions.

Plant mitochondrial genomes have a propensity for inter- and intra-genic recombination.  This results in large inter-specific variations in the size and content of the mtDNA, coding regions split into exons which require multiple splicing events prior to translation, and in some species a large number of uncharactarizable open reading frames (ORFs). The purpose of this study was to sequence and assemble the mitochondrial transcriptome of Nicotiana tabacum using next generation Illumina sequencing and obtain a genomic-level view of steady-state RNA abundance. Our hope was that this data would define the transcripts produced by the mitochondria, suggest processing events, identify expressed ORFs, and provide a global view of transcript editing. The assembled transcriptome revealed 29 distinct monocistronic and polycistronic transcripts along with large intergenic spaces with little to no detectable RNA.  Coding regions, including processed exons, were present in much higher abundance than intron regions, suggesting post-processing selective degradation of untranslated RNAs.  Tobacco has 117 uncharacterized ORFs and 18 of them were found to have steady-state RNA amounts above background in both deep-sequencing and qRT-PCR experiments.  Ten of those ORFs were found to be polysome associated, suggesting they are translated.  The assembled transcriptome  also enabled a full mitogenome screen of RNA C→U editing sites. Six hundred and thirty five potential edits were found with 557 occurring within protein-coding genes, five in tRNA genes, and 73 in non-coding regions.  Edits were found in every protein-coding transcript in the tobacco mitogenome.  Most of the non-coding region editing sites were found in 5’ and 3’ UTR regions and introns.  These results confirm that plant mitochondrial transcripts undergo extensive processing, that a small number of the uncharacterized ORFs within the tobacco mitogenome may produce functional proteins, and that RNA editing occurs in coding and non-coding regions of mitochondrial transcripts.

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Paper describing a portion of this work

1 - Biology, 1301 E. Main St, Box 60, Murfreesboro, TN, 37132, USA
2 - Middle Tennessee State University, Biology, 1301 E. Main St., Murfreesboro, TN, 37132, USA
3 - Middle Tennessee State University, Computational Sciences, 1301 E. Main St., Murfreesboro, TN, 37132, USA

Nicotiana tabacum

Presentation Type: Oral Paper:Papers for Sections
Session: 22
Location: Rapids/Grove
Date: Tuesday, July 29th, 2014
Time: 11:45 AM
Number: 22011
Abstract ID:306
Candidate for Awards:None

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