Expression of a transferred nuclear gene in a mitochondrial genome

Abstract

a b s t r a c tTransfer of mitochondrial genes to the nucleus, and subsequent gain of regulatory elements for expression, is an ongoing evolutionary process in plants. Many examples have been characterized, which in some cases have revealed sources of mitochondrial targeting sequences and cis-regulatory elements. In contrast, there have been no reports of a nuclear gene that has undergone intracellular transfer to the mitochondrial genome and become expressed. Here we show that the orf164 gene in the mitochondrial genome of several Brassicaceae species, including Arabidopsis, is derived from the nuclear ARF17 gene that codes for an auxin responsive protein and is present across flowering plants. Orf164 corresponds to a portion of ARF17, and the nucleotide and amino acid sequences are 79% and 81% identical, respectively. Orf164 is transcribed in several organ types of Arabidopsis thaliana, as detected by RT-PCR. In addition, orf164 is transcribed in five other Brassicaceae within the tribes Camelineae, Erysimeae and Cardamineae, but the gene is not present in Brassica or Raphanus. This study shows that nuclear genes can be transferred to the mitochondrial genome and become expressed, providing a new perspective on the movement of genes between the genomes of subcellular compartments.

Organellomic data sets confirm a cryptic consensus on (unrooted) land‐plant relationships and provide new insights into bryophyte molecular evolution

“…One reacquisition scenario invokes reverse transfer of tuf A from the nucleus to the plastid, while the other invokes horizontal gene transfer, perhaps from a green algal lineage (see Results). There are more‐or‐less apt precedents for all four scenarios in green‐plant organellar evolution (Adams et al., , ; Qiu et al., ; Atluri et al., ; Leliaert and Lopez‐Bautista, ; Wu et al., ), and so each should be considered a viable possibility. We hope that our unexpected discovery of tuf A in certain moss plastomes will stimulate studies designed to achieve resolution among the several complex scenarios that could have given rise to this intriguing evolutionary puzzle.…”

Mitochondrial genome of the nonphotosynthetic mycoheterotrophic plant Hypopitys monotropa, its structure, gene expression and RNA editing

“…More variation exists in the group of genes involved in translation, that is, ribosomal proteins and transfer RNAs (Adams et al, 2002;Gualberto et al, 2014), presumably due to the transfer to the nuclear genome that occurred in several plant lineages or the non-essentiality of these genes. In addition, many plant mitochondrial genomes carry open reading frames (ORFs) that potentially encode functional proteins (Qiu et al, 2014); such ORFs are highly lineage specific. Nonphotosynthetic plants are divided into two large groups-those that are parasitic on other plants and those that are mycoheterotropic.…”

High transcript abundance, RNA editing, and small RNAs in intergenic regions within the massive mitochondrial genome of the angiosperm Silene noctiflora

“…In particular, the presence of insertions from the plastid and nuclear genomes can make it difficult to assess whether transcripts matching these regions are actually originating from the mitochondrial genome. This is particularly relevant in light of the recent observation that the mitochondrial genomes of Arabidopsis thaliana and related species in the Brassicaceae contain a nuclear-derived gene that is actively transcribed [ 41 ]. Purifying or enriching for mitochondrial RNA and making comparisons to total cellular RNA are one approach to help identify true mitochondrial transcription in these cases.…”