Construction of a barley RFLP linkage map using an F₂ population

derived from a cross between Ko A and Mokusekko 3

C. Miyazaki¹, E. Osanai², K. Saeki³, N. Hirota³, K. Ito³, Y. Ukai⁴, T. Konishi⁵ and A. Saito⁶

¹ Nagasaki Laboratory, Japan Science and Technology Corporation,

2-1303-8, Ikeda, Ohmura, Nagasaki 856-0026, Japan

² Technology Development Department, Kirin Brewery Co. Ltd.

1-17-1, Namamugi, Tsurumi, Yokohama 230-8628, Japan

³ Biotechnology Department, Sapporo Breweries Ltd.

37-1, Kizaki, Nitta, Gunma 370-0393, Japan

⁴ 1994-9 Migimomi, Tsuchiura, Ibaraki 300-0837, Japan

⁵ 294 Okada, Mabi, Okayama 710-1311, Japan

⁶ Department of Crop Breeding, Kyushu National Agricultural Experiment Station,

2421, Suya, Nishigoshi, Kumamoto 861-1192, Japan

We report on the construction of a barley RFLP linkage map using 120 F₂ plants derived from a cross between Ko A and Mokusekko 3. Ko A is a Japanese two-rowed malting barley, and Mokusekko 3 is a Chinese six-rowed barley landrace.

Six restriction enzymes BamHI, BglII, DraI, EcoRV, HindIII and XbaI were chosen for the detection of polymorphism between Ko A and Mokusekko 3. Three sources of the known RFLP probes were used for the map construction; NABGMP probes (Kleinhofs et al. 1993, Kasha and Kleinhofs 1994), MWG and cMWG probes (Graner et al. 1991), and BCD, CDO and WG probes (Heun et al. 1991). New barley RFLP probes were developed in this study. The genomic DNA probes (JBG probes) were obtained from cultivar Ko A HpaII genomic DNA library. The cDNA probes (JBC probes) were isolated from cultivar Igri callus cDNA library. Linkage analysis was performed using Mapmaker version 2.0 with LOD of 3.0. Genetic distances were calculated using the Kosambi function.

The present map covers 1389 cM of the barley genome consisting of 222 loci with an average marker-to-marker distance of 6.5 cM (Fig. 1). These loci include 147 genomic DNA RFLP, 73 cDNA RFLP, one isozyme (Est1) and one morphological (vrs1) markers (Table 1). As common markers, 117 loci were mapped using the previously reported 91 probes. Furthermore, 103 loci were newly mapped on the barley genome using 57 JBG probes and 29 JBC probes. There were only three gap regions exceeding 25 cM.

We compared the present map with the Steptoe x Morex map, which is one of the most representative barley RFLP linkage maps, based on a Hordeum bulbosum (Hb)-derived DH lines (Kleinhofs 1995). The linear orders of common RFLP markers were essentially identical and no major chromosomal rearrangements were detected. The ratio of total length between F₂ map and Hb-derived DH map within common markers was 0.98. The remarkable similarities were present at the whole-genome level between both RFLP linkage maps.

Acknowledgments

We thank Drs. A. Kleinhofs, A. Graner and M. E. Sorrells for providing RFLP probes.

References

Kasha, K. J. and A. Kleinhofs (1993) Mapping of the barley cross Harrington x TR306. BGN 23: 65-69.

Kleinhofs, A., A. Kilian, M. A. Saghai Maroof, R. M. Biyashev, P. Hayes, F. Q. Chen, N. Lapitan, A. Fenwick, T. K. Blake, V. Kanazin, E. Ananiev, L. Dahleen, D. Kudrna, J. Bollinger, S. J. Knapp, B. Liu, M. Sorrells, M. Heun, J. D. Franckowiak, D. Hoffman, R. Skadsen and B. J. Steffenson (1993) A molecular, isozyme and morphological map of the barley (Hordeum vulgare ) genome. Theor. Appl. Genet. 86: 705-712.

Kleinhofs, A. (1995) NABGMP mapping update. BGN 25: 62-70.

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.

Table 1. Distribution of markers and map length of the seven barley chromosomes
Chromosome	Length	Number of markers detected				Gap^b
	(cM)	genomic DNA	cDNA	Other^a	Total
1H	169	17	10	0	27	0
2H	234	23	12	1	36	1
3H	213	28	11	1	40	1
4H	173	17	7	0	24	1
5H	249	21	15	0	36	0
6H	179	17	8	0	25	0
7H	172	24	10	0	34	0
Total	1389	147	73	2	222	3

^aIsozyme and morphological markers

^bDistance between two adjacent markers of more than 25 cM

Fig. 1. (following page) The barley Ko A x Mokusekko 3 RFLP linkage map with the short arm at the top. The map distances are given in cM on the left of the bars. The approximate centromere positions are shown by a C with vertical bar according to the previous report (Kleinhofs et al. 1993).

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