II.35. Three-point tests on chromosomes 1 and 7.
Bodil Søgaard, Danish Atomic Energy Commission Research Establishment Risø DK-4000 Roskilde and Institute of Genetics, University of Copenhagen, Denmark.
Eleven three-point tests have been performed with markers on chromosomes 1 and 7. The markers employed on chromosome 1 comprise the eceriferum locus cer-f, the albina locus, ac2, and the erectoides loci, ert-a, ert-d, and ert-m. On chromosome 7 recombination percentages have been determined for the eceriferum loci cer-zj and cer-zp, the erectoides loci ert-n and ert-g, the laxatum locus lax-a, the variegated locus va, and the aristatum locus ari-e.
The genotypes of the F2 plants were determined by analysing the progeny in F3. In crosses 1-4, involving a lethal gene (ac2) or a marker gene giving a high sterility vnder unfavourable conditions (ert-n), 18 F2 genotypes were determined, whereas in the other 7 crosses all 27 genotypes were determined. The data are given in Table 1. From these data the orders of the loci in each cross have been determined and the recombination percentages with their standard deviations have been calculated by the maximum likelihood method (Figure 1). The orders of all the loci on chromosome 1 and 7 respectively are listed in Figure 2.
Figure 2. The orders of the 5 loci on chromosome 1 and the 8 loci on chromosome 7.
The coefficient of coincidence for the 11 tests are as follows:
The tests on chromosome 1 reveal negative interference, whereas those on chromosome 7 exhibit the expected positive interference.
The details of the analysis will be published in:
Søgaard, B. 1974. The localization of eceriferum loci in barley. III. Three-point tests of genes on chromosome 1 in barley. Hereditas (in press).
Søgaard, B. 1974. The localization of eceriferum loci in barley. IV. Three-point tests of genes on chromosome 7 in barley. Hereditas (in press).
