Mitochondrial DNA Insertions in Arabidopsis Genome: is Organelle-to-Nucleus Gene Transfer Continued?

College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Sultanate of Oman
Department of Computer Science, Royal Holloway, University of London, Egham, Surrey TW20, UK
Department of Biosciences, COMSATS Institute of Information Technology, Islamabad 44000, Pakistan
Our previous studies revealed that nuclear genome of Arabidopsis contains multiple mitochondrial
DNA splinters with intact copies of many organellar genes. In this paper, using the current annota-
tions of nuclear genomes of these species, we show that nuclear copies of twelve known mitochondrial
genes from Arabidopsis respectively, have known cDNA support to be transcribed in nucleus. We also
found that nuclear copies of eleven mitochondrial ORFs, annotated as hypothetical nuclear genes in
Arabidopsis, are covered by long transcripts. So, nuclear copies of many mitochondrial genes seem to
be expressed in both genomes. Our findings suggest that, at least, some of these mitochondrial genes
represent candidates to be evolutionary transferred to nucleus and present an intermediate stage of
mitochondria-to-nucleus gene transfer process that continues at present time.