The plastid chromosome of Atropa belladonna and its comparison with that of Nicotiana tabacum: the role of RNA editing in generating divergence in the process of plant speciation.
The nuclear and plastid genomes of the plant cell form a coevolving unit which in interspecific combinations can lead to genetic incompatibility of compartments even between closely related taxa. This phenomenon has been observed for instance in Atropa-Nicotiana cybrids. We have sequenced the plastid chromosome of Atropa belladonna (deadly nightshade), a circular DNA molecule of 156,688 bp, and compared it with the corresponding published sequence of its relative Nicotiana tabacum (tobacco) to understand how divergence at the level of this genome can contribute to nuclear-plastid incompatibilities and to speciation. It appears that (1) regulatory elements, i.e., promoters as well as translational and replicational signal elements, are well conserved between the two species; (2) genes--including introns--are even more highly conserved, with differences residing predominantly in regions of low functional importance; and (3) RNA editotypes differ between the two species, which makes this process an intriguing candidate for causing rapid reproductive isolation of populations.
Botanisches Institut der Ludwig-Maximilians-Universität München, Germany.
Christian
C
Schmitz-Linneweber
Ralph
R
Regel
Tung Gia
TG
Du
Holger
H
Hupfer
Reinhold G
RG
Herrmann
Rainer M
RM
Maier
D000595:Amino Acid Sequence; D001532:Atropa belladonna / Q000235:genetics*; D001483:Base Sequence; D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics*; D017124:Conserved Sequence / Q000235:genetics; D019143:Evolution, Molecular; D017343:Genes, Plant / Q000235:genetics; D007438:Introns / Q000235:genetics; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D018087:Plastids / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D017393:RNA Editing / Q000235:genetics*; D018741:Replication Origin / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D014026:Nicotiana / Q000235:genetics*