Molecular evidence for a natural primary triple hybrid in plants revealed from direct sequencing.
OBJECTIVE
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.


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.
Kaplan
Zdenek
Z
Institute of Botany, Academy of Sciences of the Czech Republic, CZ-252 43 Průhonice, Czech Republic. kaplan@ibot.cas.cz
Fehrer
Judith
J
D001483:Base Sequence; D018742:DNA, Chloroplast / Q000737:chemistry / Q000235:genetics; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D006824:Hybridization, Genetic / Q000235:genetics*; D019684:Magnoliopsida / Q000235:genetics* / Q000254:growth & development; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
D018742:DNA, Chloroplast; D018744:DNA, Plant