Supported by USDA-CSU Cooperative Research Project and CSU Hatch project.

Some progresses were made since the publication of the last linkage maps in barley (Tsuchiya, 1984). The numbers of genes mapped (Table 1; Fig. 1) and associated but not mapped (Table 1) are 117 and 95, respectively. Some changes in linkage and linkage maps are briefly described below:

Chromosome 1:

Combining the results of telotrisomic and conventional analysis (Shahla and Tsuchiya, unpublished) the order of three closely linked genes, br, f_c, , and gs 3 was determined as Centromere-gs3-f_c-br as shown in the map (Fig. D)

Chromosome 2:

The gene symbol rin for reduced internode number in 2L was changed to lin for low internode number and the new symbol is used in the map (Fig. 1).

Chromosome 3:

The results from acrotrisomic analysis with acrotrisomic line 3L^3S (Triplo 3L^3S) andfive genes in the short arm (3S), x_s, a_n, yst 2, al and a_c suggested that the order of two genes in the middle segment of 3S may have to be reversed; from Centromere-al-yst2 to Centromere-yst2-al, although final conclusion may have to be given after more data are obtained (Tsuchiya, Shahla and Hang, 1986).

Chromosome 4:

The detailed analysis of telocentric chromosome 4L and acrocentric chromosome 4L^4S showed that there are deficiencies in both arms (4L and 4S). The present linkage map was developed based on the results of telotrisomic (4L) and acrotrismic analysis (4L^4S) with those deficiencies. It is possible that gene-chromosome association may have to be revised for some genes. With the newly obtained acrotrisomic line for 4L^4SB and another telocentric chromosome (4s.L-inv), genetic analysis is now under way to find correct association of genes with respective arms.

Chromosome 5:

In the 5th International Barley Genetics Symposium held in Okayama, Japan, the International Committee for Nomenclaure and Symbolization for Barley Genes recommended and approved that old symbols of M1 and ml should be used for resistance and susceptibility of powdery mildew (Erisiphe graminis hordei) , instead of Reg and reg which were introduced previously (Haus, 1977; Sogaard Jørgensen, 1984).

Similarly some genes for powdery mildew resistance in chromosome 4 were also changed from Reg vs. reg to Ml vs. ml

However, the old symbols have to be re-established in relation to the present system by the Coordinator for disease resistant genes. As soon as the old system is restored, the gene symbols in the maps will be changed accordingly.

Chromosome 6:

No important change has been made in the map of chromosome 6.

Chromosome 7:

Telotrisomic analysis showed that the gene ddt for DDT resistance is located in the short arm of 7 (7S).

Based on these results, centromere positions were located in genetic linkage maps of all seven barley chromosomes and at least one gene is located in each of 14 amms (Fig. 1).

As shown in Table 1, there are many genes which were associated with chromosomes but not located in the maps. Also there are many more genetic stocks or mutants that are not genetically well analyzed yet. These materials are used in the future improvement of linkage maps in barley.

Table 2 lists genes and genetic stocks most of which are available at the Barley Genetic Stock Center in the Department of Agronomy, Colorado State University.

References:

Haus, T. E. 1977. Linkage information as of April, 1977. Barley Genet. Newsl. 7:101-102.

Shahla, A. and T. Tsuchiya (unpublished) . Cytogenetics studies in barley chromosome 1 by means of telotrisomic, acrotrisomic and conventional analysis.

Søgaard, B. and J. M. Jørgensen. 1984. Supplementary List No. I (to master list of barley genes): Genes for reaction to Erysiphe graminis hordei (powdery mildew) . Barley Genet. Mesi. 14:173-182.

Tsuchiya, T. 1984. Linkage maps of barley (Hordeum vulgare L.) . Genetic Maps 3:508-521.

Tsuchiya, T., A. Shahla, and A. Hang (1986) Acrotrisomic analysis in barley. Proc. 5th Intern. Barley Genet. Symp., Okayama, Japan (In press).