Coordinator's report: Translocations and balanced tertiary trisomics
Gottfried Künzel
Institute of Plant Genetics and Crop Plant Research, D-06466 Gatersleben, Germany.

As suggested during the 6th International Barley Genetics Symposium at Helsingborg, seed samples from the world collection of translocations consisting of 625 stocks were transferred from Dr. R.T. Ramage, USDA-ARS, Tucson, to Gatersleben. These translocation lines will be propagated in 1996. To prevent as much as possible a loss of stocks, some single plant progenies will be harvested for cold storage in addition to bulked seeds from each stock. Considering the received material together with the translocations from Gatersleben described in BGN 22: 80-102, the world collection includes 1301 stocks represented by 1008 singly and 293 multiply interchanged karyotypes.

Hagberg et al. (1995) compiled long term studies with 21 translocations involving chromosomes 4 and 6. Combining the results of diallel crosses, karyotype analysis of root tip mitosis, and linkage studies performed preferentially with msg and ert genes, the 42 trans location breakpoints were assigned to chromosome arms. For some of these 4-6 translocations the breakpoints were allocated to specified regions of Giemsa-banded chromosomes by Kakeda and Yamagata (1991). Their results disagree in two cases. In T4-6f the breakpoints were found to be in the short arm of chromosome 4 and the long arm of chromosome 6 (S-L) in contrast to the L-S combination proposed by Hagberg et al. In T4-6o Kakeda and Yamagata allocated the breakpoints to 4S und the satellite of chromosome 6 (S-S) in contrast to the L-L combination given by Hagberg et al. (1995).

Attained by physical RFLP mapping on microisolated translocation chromosomes, a number of breakpoints were exactly integrated into the linear marker sequences of the Igri/Franka-derived RFLP maps (see Sorokin et al. 1995, and Korzun and Künzel, this volume of BGN). This knowledge, at present available for a total of 97 breakpoints (21, 37 and 39 within the linkage maps 3, 5 and 7 respectively), may stimulate barley workers for more sophisticated uses of translocations.

With respect to balanced tertiary trisomics there is no new information since the last report given in BGN 23: 157-163.

Please, submit requests for seed samples to G. Künzel under the address given above.

References:

Hagberg, G., P. Hagberg, and L. Lehmann. 1995. Segmental interchanges in barley. IV. Translocations involving chromosomes 4 and 6. BGN 24: 94-101.

Kakeda, K. and H. Yamagata. 1991. Localization of breakpoints in barley reciprocal translocations involving chromosome 4 by banding techniques. Barley Genetics VI, Vol. I, 280-282.

Korzun, Larissa and G. Künzel. 1996. Integration of translocation breakpoints of barley chromosomes 3 and 7 into the Igri/Franka-derived RFLP maps. BGN 25:

Sorokin, A., F. Marthe, and G. Künzel. 1995. Integration of 37 translocation breakpoints of barley chromosome 5 into the Igri/Franka derived RFLP map. BGN 24: 108-112.