RECOMMENDATIONS FOR THE DESIGNATION OF THE BARLEY CHROMOSOMES AND THEIR ARMS

At the business meeting of the 7th International Barley Genetics Symposium held at the University of Saskatchewan, Saskatoon, Saskatchewan, Canada, on August 5, 1996, the following resolution on the designation of the barley chromosomes and their arms, and on the selection of a reference genome in the Triticeae was passed:

1. Each of the seven barley chromosomes is designated by a figure from 1 to 7 according to its homoeologous relationships with chromosomes of other Triticeae species. The figure is followed by the letter H; e.g., 2H.

2. The genomes of Hordeum vulgare and H. bulbosum are symbolized by the letter H.

3. The chromosome arms are designated by the letters S and L.

4. The barley genome present in the variety 'Betzes' becomes the reference genome in the Triticeae to which definitions of translocations, short arm/long arm reversals, etc. are standardized in all species.

Notes on the four points of the resolution:

l. The seven barley chromosomes should be designated as follows:

Recommendation:

lH 2H 3H 4H 5H 6H 7H

Burnham & Hagberg designations (acc. to Sinqh & Tsuchiya (1982)

5 2 3 4 7 6 1

It is not recommended to give the Burnham & Hagberg numbering together with the homoeologous numbers in publications, although authors may choose to do so, with the Triticeae nomenclature given prominence. It is MOST IMPORTANT that the genomic symbol H is included with the number, when the Triticeae system is used. otherwise readers will tend to confuse just a number with the Burnham & Hagberg numbering system.

2. The use of the genomic symbol H instead of I as proposed by Love (1984) agrees with usage by most barley workers, but goes against a proposal for the designation of all Triticeae genomes presented in the Proceedings of the 2nd International Triticeae Symposium (Wang & al. 1996).

3. The two arms of the chromosomes of barley are designated by the upper case letters S (for the short arm) and L (for the long arm) according to the definitions by Singh & Tsuchiya (1982). The arm designation should follow the chromosome and genome designations without a space, e.g., 6HL. The arm designations given in recent molecular marker maps (e.g., Kleinhofs & al. 1993; Devos & al. 1993) should henceforth be regarded as 'names' not as referring to physically long and short arms, so no further reversals will be made.

4. The selection of the barley genome in the variety 'Betzes' as the reference genome in the Triticeae is based on the fact that barley is an excellent standard: it is diploid (unlike wheat), easy to grow and multiply under laboratory conditions world-wide (unlike Aegilops species), wheat addition lines are available for 'Betzes', and barley is economically important so other Triticeae workers have an incentive to test their probes, etc. on barley.

The contents of the resolution had previously been discussed and passed at a workshop "Designation of the Barley Chromosomes" on August 2. The discussion was based on recommendations drawn up by a committee consisting of I. Linde-Laursen, Copenhagen, Denmark, J.S. Heslop-Harrison, Norwich, United Kingdom, K.W. Shepherd, Adelaide, Australia, and S. Taketa, Kurashiki, Japan. The committee had been set up by the organizers of the symposium with the mandate to prepare recommendations for a standard nomenclature system of the barley chromosomes on the basis of a literature survey of the barley genome. The problem was last discussed at the 6th International Barley Genetics Symposium in Helsingborg in 1991 (Lundqvist and Franckowiak 1992).

On the basis of the information available in the literature, it was obvious that

(i) the seven chromosomes of barley (H. vulgare L. ) largely have the same genetic content as those in other members of the Triticeae; and

(ii) the gene loci in barley are largely collinear with the loci in other members of the Triticeae, with few ancestral translocations involving whole chromosome segments.

All available data thus show a high level of conserved synteny among the chromosomes throughout the Triticeae, and it is clear that the whole group can be treated as a single gene pool. Therefore, the committee recommended that the currently used designations of the chromosomes of barley (Burnham & Hagberg 1956; see Singh & Tsuchiya 1982) were changed to follow a system in accordance with the current wheat homoeologous group numbering (the Triticeae system), a point-of-view which was as mentioned later adopted by the barley symposium.

References:

Burnham, C.R. & Hagberg, A. 1956. Cytogenetic notes on chromosomal interchanges in barley. Hereditas 42: 467-482.

Devos, K.M., Miller, T. & Gale, M.D. 1993. Comparative RFLP maps of the homoeologous group-2 chromosomes of wheat, rye and barley. Theor. Appl. Genet. 85: 784-792.

Kleinhofs, A. & al. 1993. A molecular, isozyme and morphological map of the barley (Hordeum vulgare) genome. Theor. Appl. Genet. 86:,705-712.

Love, A. 1984. Conspectus of the Triticeae. Feddes Repert. 95: 425-521.

Lundqvist, U. & Franckowiak, J.D. 1992. Committee and workshop summary. Mutations, gene mapping and nomenclature. Barley Genetics VI: 855-857.

Singh, R.J. & Tsuchiya, T. 1982. Identification and designation of telocentric chromosomes in barley by means of Giemsa N-banding technique. Theor. Appl. Genet. 64: 13-24.

Wang, R. R.-C., Bothmer, R. von, Dvorak, J., Fedak, G., Linde-Laursen, I. & Muramatsu, M. 1996. Genome symbols in the Triticeae (Poaceae). In: Proceedings of the 2nd Inter- national Triticeae Symposium, Logan, Utah, June 2O-24, 1994. Eds. R. R.-C. Wang, K.B. Jensen & C. Jaussi. Utah State University, p. 29-34.