Genomic affinities of individual chromosomes based on C- and N-banding analyses of tetraploid Elymus species and their diploid progenitor species

Giemsa C- and N-banding techniques were used to identify individual somatic chromosomes in the tetraploid (2n = 28) species Elymus trachycaulus (= Agropyron trachycaulum) (genome designation SH) and E. ciliaris (= A. ciliare) (SY) and five diploid progenitor species (2n = 14), Pseudoroegneria spicata (= A. spicatum) (S), P. libanotica (= A. libanoticum) (S), P. stipifolia (= A. stipifolium) (S), Critesion bogdanii (= Hordeum bogdanii) (H), and C. californicum (= H. californicum) (H). Comparisons based on banding patterns of E. trachycaulus and E. ciliaris with parental donor species P. spicata indicated a common S genome origin. The heterochromatin composition of several E. trachycaulus chromosomes were similar to chromosomes of both Critesion species. However, the possible origin of characteristic C- and N-banded chromosomes of E. ciliaris remained undetermined. These patterns of evolution among genomes of E. trachycaulus, E. ciliaris, and their progenitor species proved valuable for the allocation of individual chromosomes into specific genomes. This approach may be useful for the genomic allocation of wheat-Elymus addition lines. Key words: C-banding, N-banding, Elymus, Triticeae, genome.

The heterochromatin distribution and genome evolution in diploid species of Elymus and Agropyron

The acetocarmine–Giemsa C-banding technique was used to study heterochromatin distribution in somatic chromosomes of diploid Elymus junceus (= Psathyrostachys juncea) (2n = 14) (genome designation Ju = N) and nine diploid Agropyron species (2n = 14): A. cristatum (C = P), A. imbricatum (C = P), A. elongatum (= Elytrigia elongata = Thinopyrum elongatum) (E = J), A. junceum (= E. bessarabicum = T. bessarabicum) (J = E), A. spicatum (= Pseudoroegneria spicata) (S), A. libanoticum (= P. libanotica) (S), A. ferganense (S), A. stipifolium (= P. stipifolia) (S), and A. velutinum (V). With the exception of A. elongatum and A. velutinum, which were self-fertile, all species were cross-pollinating and self-sterile. The cross-pollinating species showed large terminal C-bands and a high level of C-band polymorphism. Agropyron elongatum, moderately self-fertile, showed small terminal and interstitial bands and a minimal C-band polymorphism. Agropyron velutinum, fully self-fertile, almost totally lacked C-bands. The Ju, C, E, and J genomes appeared to be distinctive and the equivalence of the E and J genomes was not supported from their C-banding patterns. Four species sharing the S genome, A. spicatum, A. libanoticum, A. ferganense, and A. stipifolium had C-band patterns similar to one another, although C-bands were less prominent in A. stipifolium than others.Key words: C-banding, karyotype, wheatgrass, cytology.