GrainGenes

Physical mapping of RFLP loci by PCR of STS derivatives from mapped RFLP probes with DNA obtained from microisolated translocated chromosomes (Sorokin et al. 1994a, Künzel and Korzun 1996) resulted so far in cytogenetically integrated linkage maps for chromosomes 1H, 2H, 3H, 5H and 6H (Sorokin et al. 1994b, Korzun and Künzel 1995; 1996 and Triticeae Genome Database GrainGenes: 'http://probe.nalusda.gov:8300/cgi-bin/browse/graingenes' under "Map_Data", "Barley, physical").

Here, we report on results for chromosome 4H. To relate defined subregions of the chromosome to corresponding regions of the Igri/Franka linkage map 4H, a total of 31 translocation breakpoints (TB's) have been mapped between the sequence of RFLP markers (Table 1). Using DNA obtained from microisolated telosomes as a template for PCR, the centromere was allocated to an interval of 5.9 cM between MWG2036 and RIS39. This interval corresponds to a physical segment of at least 33% of the total chromosome length. On the long arm, a number of co-segregating markers could be physically arranged by inserted TB's. The chromosomal positions of the six TB's mapped between the markers clustering at 61.1 cM within the genetic map indicating that the markers of this cluster are physically spread over a segment comprising about 30% of the long arm. Co-segregating markers at the genetic positions of 67.0 cM and 74.2 cM could be also physically arranged by inserted TB's. As previously shown for chromosomes 1H, 2H, 3H, 5H and 6H, again a majority of TB's is clustered within a large median region of chromosome 4H which is characterized by low recombination rates and by only few markers on the Igri/Franka map.

Including this report, a total of 210 TB's have been mapped on six of the seven Igri/Franka-derived linkage groups: 1H (38), 2H (33), 3H (32), 4H (31), 5H (39) and 6H (37). To complete this type of TB-mapping for the entire barley genome, work is in progress for chromosome 7H.

Acknowledgment

This research was supported by the BMBF and the DFG (Grant No. 0311002 and KU 1129/1-1).

References:

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Graner, A., E. Bauer, A. Kellermann, S. Kirchner, J.K. Muraya, A. Jahoor, and G. Wenzel. 1994. Progress of RFLP-map construction in winter barley. BGN 23: 53-59.

Korzun, L. and G. Künzel. 1995. Integration of translocation breakpoints of barley chromosomes 3 and 7 into the Igri/Franka derived RFLP maps. BGN 25: 13-16.

Korzun, L. and G. Künzel. 1995. Integration of 70 translocation breakpoints into the Igri/Franka-derived RFLP maps for 2H and 6H. BGN 27: 75-78.

Künzel, G. 1993. Coordinator's report: Translocations and balanced tertiary trisomics. BGN 22: 80-102.

Künzel, G. and L. Korzun. 1996. Physical mapping of cereal chromosomes, with special emphasis on barley. Proc. V. International Oat Conference & VII. International Barley Genetics Symposium, Vol. 1. Invited Papers, 197-206.

Linde-Laursen, I. 1988. Giemsa C-banding of barley chromosomes. V. Localization of breakpoints in 70 reciprocal translocations. Hereditas 108: 65-76.

Marthe, F. and G. Künzel. 1994. Localization of translocation breakpoints in somatic metaphase chromosomes of barley. Theor. Appl. Genet. 89: 240-248.

Sorokin, A., F. Marthe, A. Houben, U. Pich, A. Graner and G. Künzel, 1994a, Polymerase chain reaction mediated localization of RFLP clones to microisolated translocation chromosomes of barley. Genome 37: 500-555.

Sorokin, A., F. Marthe, and G. Künzel. 1994b. Integration of 37 translocation breakpoints of barley chromosome 5 into the Igri/Franka derived RFLP map. BGN 24: 108-112.