BGN 22: Linkage studies between morphological and RFLP markers in the barley genome

Linkage studies between morphological and RFLP markers in the barley genome

J. Schondelmaier, G. Fischbeck, and A. Jahoor
Institute of Agronomy and Plant Breeding
Technical University of Munich, 8050 Freising-Weihenstephan, Germany

Many morphological markers, originating mainly from mutational studies, have been assigned to specific barley chromosomes (for a review see: Wettstein-Knowles, 1992). In addition, three RFLP maps have been developed for the barley genome (Blake et al., 1991, Graner et al., 1991, Heun et al., 1991). Attempts to link both types of markers have first been made by Shin et al. (1990). The purpose of the present investigation was to extend this kind of information.

Crosses have been made between 'Glacier AC38' carrying the high amylose gene amo1 (Schondelmaier et al., 1992) and two multiple marker lines (Table 1) which were kindly provided by Franckowiak (1986). Up to 160 F₂ plants of each cross were grown in a greenhouse and 120 were randomly chosen for DNA isolation. The morphological markers were visually scored during the developmental state in which the markers were expressed. Isolation, restriction, and Southern analysis of genomic DNA were performed as described earlier (Jahoor et al., 1991). Most of the RFLP markers used in this study have been mapped to barley chromosomes by Graner et al. (1991). Additional RFLP markers were used in case that the above mentioned RFLP markers showed no polymorphism. Linkage analyses were carried out using the MAPMAKER program (Lander et al., 1987).

Linkages of the morphological markers gl, ert-i, n, lk2, and yh have been analyzed in the F₂ generation of the cross '4.2 msg24 MM × 'Glacier AC38', for the remaining markers the F₂ population originating from the cross '2.3 gs6 e li MM' × 'Glacier AC38' has been used. Due to lack of restriction fragment length polymorphism between '4.2 msg24 MM' and 'Glacier AC38' in the crucial region of chromosome 7L(5HL), no linkage was detected between RFLP markers and the morphological marker s. For this reason, chromosome 7(5H) is not included in Fig. 1. Linkage studies with RFLP's and Iga did not yield conclusive results. In addition, both multiple markers lines carry r and v (hex-v) as does 'Glacier AC38'. Consequently, r and v could not be included in this investigation.

Figure 1. Linkage relationships between morphological and RFLP markers. For each chromosome the RFLP reference map ('Vada' × '1B87') is shown at the right indicating probes, which have been proposed for the standard set (Jahoor et al., 1992). The positions of markers of the extended version of our map (Graner et al., 1991) are indicated by small bars. The corresponding map fragment on the left indicates additional markers and RFLP markers mapped in both populations (connected by a slim line). The position and chromosomal orientation of a marker gene is defined by the two RFLP markers, which were linked to the morphological marker, respetively. All distances are given in cM derived by multipoint analysis (MAPMAKER, Lander et al., 1987). The chromosomal orientation was determined by use of wheat-barley ditelosomic addition lines kindly provided by Islam (1983). S = short chromosome arm, L = long chromosome arm.

[1 (7H)]	[2 (2H)]	[3 (3H)]
[4 (4H)]	[5 (1H)]	[6 (6H)]

Table 1: Market genes and multiple marker lines included in the experiment

Table 2: List of disagreements for the position of morphological markets in the barley genome.

A detailed linkage map which includes 13 morphological markers is shown in Fig. 1. Diverging results reported in earlier publications by other authors are listed in Table 2. It needs to be mentioned that the orientation of chromosome 4 follows the proposal as suggested by Jensen (1987), which explains the conflicting data reported for yh. The markers ert-i and gl were assigned to the long arm of chromosome 4 due to the results with wheat-barley ditelosomic addition lines (Islam 1983) and some RFLP markers in that chromosomal region. For gs6 and amol the data obtained with RFLP markers do not agree with the positions described in earlier publications. In view of the much higher resolution power of the RFLP maps which are available for the barley genome, they may be a very helpful tool to verify and to specify the correct positions of morphological marker genes in the barley genome.

References:

Blake, T., L. Dahleen, J. Dvorak, P. Gustafson, P. Hayes, D. Hoffman, K. Kasha, S. Procunier, W. Kim, A. Kleinhofs, N. Lapitan, A. LaRoche, M. A. Saghai-Maroof, S. Molnar, G. Fedak, G. Scoles, R. Skadsen, M. Sorrels and S. Tanksley. 1991: An RFLP map of barley - North American genome mapping project. pp. 245-248. In L. Munck, K. Kirkegaard, and B. Jensen (ed.), Proceedings of the Sixth International Barley Genetics Symposium, Helsinborg, 1991. Munksgaard Intern. Publishers Ltd., Copenhagen.

Franckowiak, J. D. 1986. Multiple marker stocks from Beaverlodge, Canada. BGN 16:125-l26

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.

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.

Islam, A. K. M. R. 1983. Ditelosomic additions of barley chromosomes to wheat. pp. 233238. In: S. Sakamato (ed.) Proceedings of the Sixth International Wheat Genetics Symposium, Maruzen, Kyoto.

Jahoor, A, G. Backes, A. Graner, R. G. Herrmann, and G. Fischbeck. 1991. Development of RFLP markers for barley. Plant Breeding 107:73-76.

Jahoor, A., A. Graner and G. Fischbeck. 1992: Proposal for a standard set of RFLP probes. BGN 21:31-33.

Jensen, J. 1987. Linkage map of barley chromosome 4. pp. 189-199. In S. Yasuda, and T. Konishi (ed.), Proceedings of the Fifth International Barley Genetics Symposium, Okayama, 1986. Sanyo Press Ltd., Okayama.

Lander, E. S., P. Green, J. Abrahamson, A. Barlow, M. J. Daly, S. E. Lincoln, and L. Newburg. 1987. MAPMAKER: An interactive computer package for constructing primary genetic linkage maps of experimental and natural populations. Genomics 1: 174- 181.

Schondelmaier, J., A. Jacobi, G. Fischbeck, and A. Jahoor. 1992. Genetical studies on the mode of inheritance and localization of the amol (high amylose) gene in barley. Plant Breeding 109:274-280.

Shin, J. S., S. Chao, L. Corpuz, and T. K. Blake. 1990. A partial map of the barley genome incorporating restriction fragment length polymorphism, polymerase chain reaction, enzymes, and morphological marker loci. Genome 23:803-810.

Wolfe, R. I., and J. D. Franckowiak. 1990. Multiple dominant and recessive genetic marker stocks in spring barley. BGN 20: 117- 121.

Wettstein-Knowles, P. von 1992. Cloned and mapped genes: Current status. pp. 73-98. In P. R. Shewry, (ed.), Barley: Genetics, Biochemistry, Molecular Biology and Biotechnology. Alden Press, Oxford.

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