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dc.contributor.authorKrause, Kirsten
dc.contributor.authorFunk, Helena T.
dc.contributor.authorBerg, Sabine
dc.contributor.authorKrupinska, Karin
dc.contributor.authorMaier, Uwe G.
dc.date.accessioned2007-12-13T11:18:03Z
dc.date.available2007-12-13T11:18:03Z
dc.date.issued2007-08-22
dc.description.abstractBackground: The holoparasitic plant genus Cuscuta comprises species with photosynthetic capacity and functional chloroplasts as well as achlorophyllous and intermediate forms with restricted photosynthetic activity and degenerated chloroplasts. Previous data indicated significant differences with respect to the plastid genome coding capacity in different Cuscuta species that could correlate with their photosynthetic activity. In order to shed light on the molecular changes accompanying the parasitic lifestyle, we sequenced the plastid chromosomes of the two species Cuscuta reflexa and Cuscuta gronovii. Both species are capable of performing photosynthesis, albeit with varying efficiencies. Together with the plastid genome of Epifagus virginiana, an achlorophyllous parasitic plant whose plastid genome has been sequenced, these species represent a series of progression towards total dependency on the host plant, ranging from reduced levels of photosynthesis in C. reflexa to a restricted photosynthetic activity and degenerated chloroplasts in C. gronovii to an achlorophyllous state in E. virginiana. Results: The newly sequenced plastid genomes of C. reflexa and C. gronovii reveal that the chromosome structures are generally very similar to that of non-parasitic plants, although a number of species-specific insertions, deletions (indels) and sequence inversions were identified. However, we observed a gradual adaptation of the plastid genome to the different degrees of parasitism. The changes are particularly evident in C. gronovii and include (a) the parallel losses of genes for the subunits of the plastid-encoded RNA polymerase and the corresponding promoters from the plastid genome, (b) the first documented loss of the gene for a putative splicing factor, MatK, from the plastid genome and (c) a significant reduction of RNA editing. Conclusion: Overall, the comparative genomic analysis of plastid DNA from parasitic plants indicates a bias towards a simplification of the plastid gene expression machinery as a consequence of an increasing dependency on the host plant. A tentative assignment of the successive events in the adaptation of the plastid genomes to parasitism can be inferred from the current data set. This includes (1) a loss of non-coding regions in photosynthetic Cuscuta species that has resulted in a condensation of the plastid genome, (2) the simplification of plastid gene expression in species with largely impaired photosynthetic capacity and (3) the deletion of a significant part of the genetic information, including the information for the photosynthetic apparatus, in non-photosynthetic parasitic plants.en
dc.format.extent492324 bytes
dc.format.mimetypeapplication/pdf
dc.identifier.citationBMC Plant Biology 7(2007) article no 45en
dc.identifier.doidoi:10.1186/1471-2229-7-45
dc.identifier.issn1471-2229
dc.identifier.urihttps://hdl.handle.net/10037/1252
dc.identifier.urnURN:NBN:no-uit_munin_1067
dc.language.isoengen
dc.publisherBioMed Centralen
dc.rights.accessRightsopenAccess
dc.subjectVDP::Mathematics and natural science: 400::Basic biosciences: 470::Genetics and genomics: 474en
dc.titleComplete DNA sequences of the plastid genomes of two parasitic flowering plant species, Cuscuta reflexa and Cuscuta gronoviien
dc.typeJournal articleen
dc.typeTidsskriftartikkelen
dc.typePeer revieweden


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