The complete nucleotide sequences of the 5 genetically distinct plastid genomes of Oenothera, subsection Oenothera: II. A microevolutionary view using bioinformatics and formal genetic data.
A unique combination of genetic features and a rich stock of information make the flowering plant genus Oenothera an appealing model to explore the molecular basis of speciation processes including nucleus-organelle coevolution. From representative species, we have recently reported complete nucleotide sequences of the 5 basic and genetically distinguishable plastid chromosomes of subsection Oenothera (I-V). In nature, Oenothera plastid genomes are associated with 6 distinct, either homozygous or heterozygous, diploid nuclear genotypes of the 3 basic genomes A, B, or C. Artificially produced plastome-genome combinations that do not occur naturally often display interspecific plastome-genome incompatibility (PGI). In this study, we compare formal genetic data available from all 30 plastome-genome combinations with sequence differences between the plastomes to uncover potential determinants for interspecific PGI. Consistent with an active role in speciation, a remarkable number of genes have high Ka/Ks ratios. Different from the Solanacean cybrid model Atropa/tobacco, RNA editing seems not to be relevant for PGIs in Oenothera. However, predominantly sequence polymorphisms in intergenic segments are proposed as possible sources for PGI. A single locus, the bidirectional promoter region between psbB and clpP, is suggested to contribute to compartmental PGI in the interspecific AB hybrid containing plastome I (AB-I), consistent with its perturbed photosystem II activity.
Greiner
Stephan
S
Lehrstuhl für Botanik, Department Biology I, Botany, Ludwig-Maximilians-University, Munich, Germany.
Wang
Xi
X
Herrmann
Reinhold G
RG
Rauwolf
Uwe
U
Mayer
Klaus
K
Haberer
Georg
G
Meurer
Jörg
J
D001483:Base Sequence; D002736:Chloroplasts / Q000145:classification / Q000235:genetics*; D002874:Chromosome Mapping; D021901:DNA, Intergenic; D018744:DNA, Plant; D019143:Evolution, Molecular; D020224:Expressed Sequence Tags; D049810:Genetic Speciation; D018745:Genome, Plant; D005838:Genotype; D031664:Oenothera / Q000145:classification / Q000235:genetics* / Q000648:ultrastructure; D017393:RNA Editing; D012641:Selection, Genetic
D021901:DNA, Intergenic; D018744:DNA, Plant