title: Against the traffic: The first evidence for mitochondrial DNA transfer into the plastid genome.
abstract: Transfer of DNA between different compartments of the plant cell, i.e., plastid, mitochondrion and nucleus, is a well-known phenomenon in plant evolution. Six directions of inter-compartmental DNA migration are possible in theory, however only four of them have been previously reported. These include frequent cases of mitochondrion and plastid to nucleus transfer, plastid to mitochondrion transfer, and rare nucleus to mitochondrion migrations. The connection between the plastid and mitochondrial genomes in flowering plants has been viewed as a one way road. Contrary to these observations we found that a sequence widespread in the carrot mitochondrial genome, designated asDcMP, was transferred to the plastid genome of a carrot ancestor. Interestingly,DcMP was integrated into a tRNA promoter of the plastidtrnVgene, replacing the original promoter sequence. The rearrangement of the plastid genome is specific for carrot and closely related species belongingScandiceaeclade. The structure of the sequence and the presence of a 6 nt target site duplication led us to speculate that the transfer was a result of a transposition event of a non-LTR retrotransposon. These findings open interesting questions about the evolution of organellar genomes and mobile genetic elements and provide a useful plastid marker to phylogenetically delineate species relationships within theScandiceaeclade.
authors.affiliation: Department of Horticulture; University of Wisconsin; Madison, WI USA.
authors.forename: Massimo
authors.initials: M
authors.lastname: Iorizzo
authors.forename: Dariusz
authors.initials: D
authors.lastname: Grzebelus
authors.forename: Douglas
authors.initials: D
authors.lastname: Senalik
authors.forename: Marek
authors.initials: M
authors.lastname: Szklarczyk
authors.forename: David
authors.initials: D
authors.lastname: Spooner
authors.forename: Philipp
authors.initials: P
authors.lastname: Simon
keywords: Daucus carota; inter-compartmental DNA migration; plastid and mitochondrial genome; retrotransposon