2000 Volume 50 Issue 4 Pages 241-250
Most of the barley RFLP linkage maps have been constructed using doubled haploid(DH) lines as mapping materials and little information is available on barley RFLP linkage map using an F2 population. In the present study, we constructed an RFLP linkage map using 120 F2 plants derived from a cross between a Japanese two-rowed malting barley cultivar Ko A and a Chinese six-rowed barley landrace Mokusekko 3. A total of 222 loci were mapped using 177 RFLP probes, one isozyme marker and one morphological marker. The total map length was 1, 389 cM and the average marker-to-marker distance was 6.5cM. We compared the Ko A × Mokusekko 3 map with the Steptoe × Morex map, one of the most representative barley RFLP linkage maps, which is based on Hordeum bulbosum(Hb)-derived DH lines that represent a recombination in female gametes. The linear orders of 60 common RFLP markers were identical and no major chromosomal rearrangements were observed between both RFLP linkage maps. A significant difference in recombination frequency was detected at six intervals flanked by the adjacent common RFLP markers. A reduced map length was detected at four intervals in the F2 map and at two intervals in the Hb-derived DH map. Three out of the six intervals were located around the centromeric regions of chromosomes 5H and 6H. On the other hand, the ratio of total length between the F2 map and Hb-derived DH map within common markers was 0.98. Remarkable similarities were present at the whole-genome level between both RFLP linkage maps. The implication of these findings for the analysis of recombination frequency was also discussed.
