Genetic Map of Diploid Wheat, Triticum monococcum L., and Its Comparison With Maps of Hordeum vulgare L.

A genetic map of diploid wheat, Triticum monococcum L., involving 335 markers, including RFLP DNA markers, isozymes, seed storage proteins, rRNA, and morphological loci, is reported. T. monococcum and barley linkage groups are remarkably conserved. They differ by a reciprocal translocation involving the long arms of chromosomes 4 and 5, and paracentric inversions in the long arm of chromosomes 1 and 4; the latter is in a segment of chromosome arm 4L translocated to 5L in T. monococcum. The order of the markers in the inverted segments in the T. monococcum genome is the same as in the B and D genomes of T. aestivum L. The T. monococcum map differs from the barley maps in the distribution of recombination within chromosomes. The major 5s rRNA loci were mapped on the short arms of T. monococcum chromosomes 1 and 5 and the long arms of barley chromosomes 2 and 3. Since these chromosome arms are colinear, the major 5s rRNA loci must be subjected to positional changes in the evolving Triticeae genome that do not perturb chromosome colinearity. The positional changes of the major 5s rRNA loci in Triticeae genomes are analogous to those of the 18S5.8S26S rRNA loci.

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.