II.12 Independent inheritance of spontaneous genes and induced mutant genes conditioning resistance to powdery mildew.
J. Helms Jorgensen. Atomic Energy Commission, Research Establishment Riso, DK-4000 Roskilde, Denmark.
Spontaneous genes conditioning mildew resistance have been reported to be located at the Mlg (Goldfoil) locus on chromosome 4 or at a number of loci on chromosome 5, but not on any other of the barley chromosomes. On chromosome 5, gene Mlp (Psaknon) has been located on the short arm, gene Mlr-12 (Russian-12) on the long arm and gene Mla (Algerian) in between. The map distances from Mlp to Mla and from Mla to Mlr-12 are about 40 to 45 crossover units.
Nine recessive, induced mutant genes conditioning resistance to powdery mildew are found to be non-complementing alleles in one locus. Two of these mutants, Mutante-66 (from Haisa) and No. 5678 (from Carlsberg II) were crossed to Goldfoil, Psaknon, Algerian and Russian-12. The F2 segregations for resistant and susceptible seedlings showed the mutant genes to be inherited independently from genes Mlg, Mlp, Mla and Mlr-12. This suggest that the mutant genes are outside the chromosome segments on which spontaneous genes have been located.