Coordinator's report: Chromosome 5

Jens Jensen
Plant Biology Section, Environmental Science and Technology Department
Risø National Laboratory, Dk-4000 Roskilde, Denmark

Recombination data from ten different crosses (numbered 1-10 in Table 1) have been recorded from the literature and subjected to a map estimation procedure (Jensen, 1987). Three of the 29 recombination estimates from the ten crosses did not fit the map and were omitted in estimating the resulting map which is shown in Fig. 1. These data add three new loci to the map, Ml(Ga) (powdery mildew resistance), Glb1 (encoding (1-3)(1-4)D-glucan 4-glucanohyrolase EI), and the RFLP locus xMSU51. Among recombination frequencies involving loci Mla and Gpi1, four omitted from the previous map fit the present bulk of data and are included in estimating the map in Fig. 1, whereas one that fitted the previous map had to be omitted.

The addition of the new data and the above mentioned adjustment has decreased the standard deviation of most map positions in Fig. 1. The present map deviates from previous ones in that the hyphen in loci symbols has been omitted. Further, the order of loci Gpi1 and Lys4 is reversed, and the map has become slightly shorter, by 4.6 cM; this is, however, not statistically significant.

The map includes the first RFLP marker, xMSU51, which can be mapped on barley chromosome 5 based on reported data. The linkage maps based on RFLP data and described by Heun et al. (1991) and Graner et al. (1991) include maps of chromosome 5. However, the segregation data and the recombination percentages used to calculate their maps were not reported, and as a consequence their data could not be utilized to improve the present map. It is hoped that future RFLP data may be documented in such a way that the RFLP loci can be utilized and contribute to improve and enrich our linkage map. Linkage data that may appear in BGN Vol. 20 are not included as that volume is not yet available.

Table 1. Recombination percentages considered for improving the linkage map of barley chromomsome 5.

Fig 1. The barley chromosome 5 linkage map with the best fit to all linkage data available in the scientific literature. The map positions are given in centimorgans (cM). The order and positions of closely linked loci may not be definitive. The position of the centromere is probably slightly above that of locus fs2.

References:

Graner, A., A. Jahoor, J. Schondelmaier, H. Siedler, K. Pillen, G. Fischbeck, G. Wenzel, and R.G. Herrmann. 1991. Construction of an RFLP map of barley. Theor. App. Genet. 83:250-256.

Heun, M., A. E. Kennedy, J. A. Anderson, N. L. V. Lapitan, M. E. Sorrells, and S. D. Tanksley. 1991. Construction of a restriction fragment length polymorphism map for barley (Hordeum vulgare). Genome 34:437-447.

Hossain, M. A. and D. H. B. Sparrow. 1991. Resistance to powdery mildew (Erysiphe graminis f. sp. hordei) in the cultivar Galleon. II. Chromosomal location and linkage with hordein protein genes. Euphytica 52:11-17.

Jensen, J. 1987. Linkage map of barley chromosome 4. In: Barley Genetics V. Okayama, Japan: 189- 199.

Kjaer, B., V. Haahr, and J. Jensen. 1991. Association between 23 quantitative traits and 10 genetic markers in a barley cross. Plant Breeding 106:261-274.

MacLeod, L. C., R. C. M. Lance, and A. H. D. Brown. 1991. Chromosomal mapping of the Glbl locus encoding (1-3)(1-4)-,B-D-glucan 4-glucanohydrolase EI in barley. J. of Cereal Sci. 13:291-298.

Schon, C. C., P. M. Hayes, T. K. Blake, and S.J. Knapp. 1991. Gametophyte selection in a winter x spring barley cross. Genome 34:918-922.

Shin, J. S., S. Chao, L. Corpuz, and T. Blake. 1990. A partial map of the barley genome incorporating restriction fragment length polymorphism, polymerase chain reaction, isozyme, and morphological marker loci. Genome 33:803-810.

Sall, T. 1991. Genetic control of recombination in barley. III. Recombination between the hordein loci in three different genotypes. Hereditas 115:13-16.

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