The Localization of Eceriferum Loci in Barley. III. Three Point Tests of Genes on Chromosome 1 in Barley

Three different 3-point tests have been made for gene distances on chromosome 1 in barley (Hordeum vulgare L.). In all cases eceriferum, cer-f9, and albina, ac2, were examined with erectoides as the third gene. The erectoides, ert, genes are ert-a23, ert-d33 and ert-m40, respectively. The analyses have been carried through to F3. The experiments demonstrated the following sequence of the five genes: cer-f9 — ac2 — ert-d33 — ert-a23 — ert-m40 and the following distances: cer-f9 — ac2 = 2.3 %, ac2 — ert-a23 = 8.5 %, ac2 — ert-d33 = 2.5 % and ac2 — ert-m40 = 12.8 %. The cer-f9 — ac2 distance, which was evaluated in all three tests, came out with the same value, 2.3 %. An evaluation of interference gave a coefficient of coincidence of 2.3 in the ert-a23 case, 8.7 for ert-d33 and 1.9 for ert-m40. This corresponds to a highly negative interference in all tests. Since the material consisted of ample samples as F3's it seems unlikely that our results are due to statistical variations. To our knowledge these are the first published three point tests in barley analysed in detail and constitute a novel example of negative interference in a higher plant. The distances over which negative interference was operative are extraordinary large when compared to the distances reported for negative interference in lower plants, e.g. Neurospora and Aspergillus.