Inferring the History of the Polyploid Silene aegaea (Caryophyllaceae) Using Plastid and Homoeologous Nuclear DNA Sequences

The origin of the rare allotetraploid Silene aegaea was inferred from plastid rps16 intron sequences, homoeologous copies of nuclear ribosomal internal transcribed spacer (ITS) sequences, and an intron from the nuclear gene coding for the second largest subunit of RNA polymerase II (RPB2). The nuclear DNA regions support the S. sedoides and S. pentelica lineages as most closely related to the two S. aegaea paralogues. A few recombinant ITS sequences were found, but as PCR recombination could be demonstrated, no true recombination could be demonstrated. No recombination was found in the RPB2 sequences. Plastid rps16 intron sequences strongly support S. pentelica as the maternal lineage. The strength of the approach of using homoeologous sequences of several loci is demonstrated, and its usefulness for the study of phylogenies of groups including polyploids is emphasized.