Chromosome analysis in investigation of the origin of the B- and G-genomesof polyploid wheats

Polyploid wheats representing two evolutionary lineages of the genus Tritic um L.: Emmer (AABBDD) and Timopheevi (A(t)A(t)GG), and diploid Triticum and Aegilops species which are considered the most probable donors of their ge nomes were studied using C-banding technique and in situ hybridization with four cloned DNA sequences. The diploid wheat species were similar with res pect of karyotype structures and C-banding patterns of chromosomes. This fa ct as well as significant differentiation of chromosomes of diploid wheat f rom the respective chromosomes of polyploid Triticum species hinders identi fication of the immediate ancestor of the A-genome. The results of comparat ive analysis of diploid Aegilops species of the Sitopsis group indicate tha t the putative donor of B- and G-genomes is the most closely related to Ae. speltoides (S-genome); the B-genome being more modified from the parental than the G-genome. It was established that the D-genomes of polyploid wheat and polyploid Aegilops species were derived from different biotypes of Ae. squarrosa.