Trigenomic origin of the hexaploid Psammopyrum athericum (Triticeae : Poaceae) revealed by in-situ hybridization

The genomic constitution of the hexaploid Psammopyrum athericum was studied with in-situ DNA hybridization using both genomic DNA and isolated cloned sequences as probes. A genomic probe from Thinopyrum bessarabicum (E genome ) hybridized successfully to 14 chromosomes of Ps. athericum and a probe fr om Festucopsis serpentinii (L genome) hybridized to another 14 chromosomes. The remaining chromosomes did not hybridize, apart from in the centromeric region, to any of the genomic probes used. It is thus proposed that Ps. at hericum contains the genomes E, L and X where X stands for a so-far unknown genome. Psammopyrum athericum has three pairs of pTa71 sites and approxima tely 30 pSc119:2 sites. The origin of the third genome will be a matter for further research using genomic and genome-specific probes.