A Database for Triticeae and Avena
II.7. Chromosome location of locus mlo conditioning
resistance to powdery mildew.
J. Helms Jørgensen. Danish Atomic Energy Commission. Research
Establishment Risø, DK-4000 Roskilde, Denmark.
An induced mutant gene in a locus designated mlo conditioning
resistance to the powdery mildew fungus (Erysiphe graminis f. sp.
hordei) is inherited independently of the spontaneous mildew resistance
genes Mlo, Mlp, Mlr12,
and Mls on chromosome 5 and Mlg on
chromosome 4 (Jørgensen 1971). In order to locate mlo
to one barley chromosome the resistant mutant R 5678 (CI 15219) was crossed
to a trisomic set of barley lines. Trisomic F1 hybrids were selfed and
the seven F2 seedling populations were scored for reactions to culture
59.11 of E. graminis hordei with the following
The F2 population from chromosome 4 trisomics segregating 8.5 per cent
resistant seedlings indicate that mlo is located on chromosome
4, probably on the short arm because mlo is independent
of mlg on the long arm. Locus mlo is
being mapped relative to known marker genes on chromosome 4.
Jørgensen, J. Helms, 1971. In: Mutation Breeding for Disease
Resistance, Intern. Atomic Energy Agency, Vienna, 117-124.
BGN 2 toc
BGN Main Index