The barley genome and its relationship with the wheat genomes. A survey with an internationally agreed recommendation for barley chromosome nomenclature

The paper reviews recent literature on the cytology, cytogenetics, molecular cytogenetics, and gene structure of barley, and on the relationship of the barley and wheat genomes. The information collected demonstrates largely similar genetic contents and collinearity of gene loci in the seven chromosomes of barley and in those of other members of the Triticeae. The high level of synteny indicates that the whole group can be considered as a single gene pool. On this basis, the 7th International Barley Genetics Symposium recommended that (i) the currently used designations of the barley chromosomes (the BURNHAM and HAGBERG system) should become secondary to the use of the Triticeae system; i.e., each of the seven barley chromosomes is designated by a numeral between 1 and 7 according to its homoeologous relationship with the chromosomes of the wheat genomes followed by the genomic symbol H, e.g., 2H; (ii) the genomes of Hordeum vulgare and H. bulbosum are symbolized with the letter H; and (iii) the arms of the barley chromosomes are designated by the capital letters S and L (cf SINGH and TSUCHIYA 1982b). Further, it was recommended that the barley genome present in the barley cultivar 'Betzes' should become the reference genome in the Triticeae.