Institute of Plant Genetics and Crop Plant Research
D-06466 Gatersleben, Germany
Physical mapping of RFLP loci by PCR of STS derivatives from mapped RFLP probes with DNA obtained from microisolated translocated chromosomes according to Sorokin et al. (1994a) and Künzel and Korzun (1996) resulted so far in cytogenetically integrated linkage maps for chromosomes 1H(5), 2H(2), 3H(3), 4H(4), 5H(7) and 6H(6) (Sorokin et al. 1994b, Korzun and Künzel 1995; 1996; 1997 and database GrainGenes:'http://www.graingenes.org/cgi-bin/WebAce/webace?db=graingenes', "Map-Data", "Barley, physical"). To finish this type of physical mapping for the entire barley genome, 32 translocation breakpoints (TB's) have been integrated into the linkage map 7H(1).
Similar to chromosomes 2H, 3H and 4H, translocations involving one SAT-chromosome, e.g. T7H-5H(1-7) or T7H-6H(1-6), were preferentially used to ensure that at least one of the two interchanged chromosomes (the satellited one) could be individually microisolated for PCR. To obtain reliable mapping results, the reciprocal breakpoints were also integrated into the RFLP maps of SAT chromosomes 5H and 6H.
Using the DNA of microisolated telosomes as a template for PCR, the centromere was localized to the 123.7 cM position between the cosegregating markers cMWG649a and PBI21b (Table 1). Since no breakpoints were found between the centromere and these two markers, the location of cMWG649a on the short arm and PBI21b on the long arm was additionally confirmed by STS analyses carried out on DNA from wheat-barley telo 7HS and telo 7HL addition lines via PCR with primers that amplify polymorphic fragments among wheat ('Chinese Spring') and barley ('Betzes'). The chromosomal positions of the six TBs mapped between cosegregating markers surrounding the centromere suggest that this 123.7 cM cluster of markers is spread over a physical segment comprising at least 30% of the total chromosome length. Six other clusters of cosegregating markers at the positions of 21.8 cM, 27.5 cM, 54.4 cM, 120.8 cM, 128.0 cM and 148.9 cM have been physically split at least partially by inserted TBs. Compared to all other chromosomes there is a less distinct clustering of TB's (only 9 out of 32) within the median region of chromosome 7H (about 43% of chromosome length) which is characterized by low recombination rates.
Including this report, a total of 292 TB's have been mapped on the seven Igri/Franka-derived linkage groups: 1H (41), 2H (33), 3H (31), 4H (30), 5H (73), 6H (52) and 7H (32). Applying a software package specifically developed for that purpose, we are currently working on a final complex data analysis which combines the chromosomal and map positions of all the 292 TB's for mutual improvements to construct physically integrated RFLP maps of high resolution for the entire barley genome.
| Marker2 | Position (cM) | Breakpoints3 |
|---|---|---|
| MWG851a | 4.3 | |
| MWG2018 | 4.3 | |
| RIS45a | 10.3 | |
| MWG555a | 11.7 | |
| MWG2074 | 18.9 | |
| MWG807 | 21.8 | |
| T17aq | ||
| MWG530 | 21.8 | |
| PBI35 | 24.7 | |
| MWG799 | 24.7 | |
| MWG2232 | 24.7 | |
| MWG2256 | 27.5 | |
| T17ai | ||
| MWG2259 | 27.5 | |
| T16i | ||
| MWG2157 | 27.5 | |
| T16ai | ||
| cMWG703 | 33.4 | |
| T14al | ||
| MWG564 | 40.4 | |
| T16av | ||
| cMWG773 | 47.5 | |
| MWG2291 | 53.1 | |
| MWG2170 | 54.4 | |
| MWG89 | 54.4 | |
| MWG527 | 54.4 | |
| T17af | ||
| MWG622 | 54.4 | |
| cMWG721 | 54.4 | |
| MWG832 | 54.4 | |
| ABG380 | 54.4 | |
| T16aw | ||
| MWG980 | 54.4 | |
| ABC167a | 54.4 | |
| ABG497b | 54.4 | |
| MWG836 | 72.7 | |
| T15a, T16ar, T16as | ||
| MWG2310 | 81.5 | |
| T16ag | ||
| ABC156d | 93.1 | |
| MWG2301 | 103.1 | |
| MWG2072 | 103.1 | |
| cMWG729 | 103.1 | |
| cMWG704 | 105.9 | |
| MWG815 | 105.9 | |
| MWG2046 | 108.8 | |
| MWG511 | 110.2 | |
| MWG2223 | 110.2 | |
| cMWG741 | 110.2 | |
| MWG977 | 110.2 | |
| MWG626 | 113.3 | |
| T13k | ||
| MWG2216 | 120.8 | |
| T14af, T17ad | ||
| MWG2304 | 120.8 | |
| cMWG725 | 123.7 | |
| T15ak | ||
| MWG808 | 123.7 | |
| T15am, T16ah, T16ak, T16an | ||
| cMWG649 a | 123.7 | |
| CENTROMERE | ||
| PBI21b | 123.7 | |
| T17ac | ||
| MWG957 | 123.7 | |
| T16au, T17aj, T17an | ||
| MWG2031 | 128.0 | |
| T17ah | ||
| RIS15 | 128.0 | |
| T15v, T17ae, T17ag, T17ao, T17au | ||
| MWG825 | 148.9 | |
| T16ap | ||
| cMWG696 | 148.9 | |
| MWG2270 | 153.8 | |
| ABC310b | 153.8 | |
| MWG599 | 158.1 | |
| MWG528 | 158.1 | |
| MWG633 | 158.1 | |
| cMWG728 | 158.1 | |
| Ris44 | 158.1 | |
| MWG2269 | 164.3 | |
| MWG539 | 172.8 | |
| MWG2262a | 175.7 | |
| T13as | ||
| ABG461 | 177.2 | |
| RIS19 | 180.1 | |
| MWG2062 | 200.1 |
1according to Graner et al. 1991, 1994 and Graner, personal communication
2only markers used for PCR mapping are included starting from the end of the short arm
3for description of translocations see Künzel (1993), Marthe and Künzel (1994), Linde-Laursen (1988)
Acknowledgement: This research was supported by the DFG (Grant KU 1129/1-1).
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. Appl. Genet. 83: 250-256.
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. 1996. Integration of 70 translocation breakpoints into the Igri/Franka-derived RFLP maps for 2H and 6H. BGN 27: 75-78.
Korzun, L. and G. Künzel. 1997. Integration of 31 translocation breakpoints of chromosome 4H into the corresponding Igri/Franka-derived RFLP map. BGN 28:23-25.
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.