AOBPreview published online on May 3, 2007
Annals of Botany, doi:10.1093/aob/mcm072
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Molecular Evidence for a Natural Primary Triple Hybrid in Plants Revealed from Direct Sequencing
Institute of Botany, Academy of Sciences of the Czech Republic, CZ-252 43 Pr
honice, Czech Republic
* For correspondence. E-mail kaplan{at}ibot.cas.cz
Received: 3 January 2007 Returned for revision: 22 January 2007 Accepted: 19 February 2007
Background and Aims: Molecular evidence for natural primary hybrids composed of three different plant species is very rarely reported. An investigation was therefore carried out into the origin and a possible scenario for the rise of a sterile plant clone showing a combination of diagnostic morphological features of three separate, well-defined Potamogeton species.
Methods: The combination of sequences from maternally inherited cytoplasmic (rpl20-rps12) and biparentally inherited nuclear ribosomal DNA (ITS) was used to identify the exact identity of the putative triple hybrid.
Key Results: Direct sequencing showed ITS variants of three parental taxa, P. gramineus, P. lucens and P. perfoliatus, whereas chloroplast DNA identified P. perfoliatus as the female parent. A scenario for the rise of the triple hybrid through a fertile binary hybrid P. gramineus x P. lucens crossed with P. perfoliatus is described.
Conclusions: Even though the triple hybrid is sterile, it possesses an efficient strategy for its existence and became locally successful even in the parental environment, perhaps as a result of heterosis. The population investigated is the only one known of this hybrid, P. x torssanderi, worldwide. Isozyme analysis indicated the colony to be genetically uniform. The plants studied represented a single clone that seems to have persisted at this site for a long time.
Key words: Triple hybrid, interspecific hybridization, Potamogeton, Potamogetonaceae, internal transcribed spacer, reproductive isolation, clonal propagation, asexual reproduction