II.51. Occurrence of the mlo locus for mildew resistance.
M. S. Wolfe and R. A. Finch. Plant Breeding Institute, Trumpington, Cambridge, England.
Genetical analysis of F1 and F2 populations from crosses involving Mutante 66 and a derivative of MC20 with three Gatersleben accessions obtained from Ethiopia, revealed that all five lines possess a common, recessive allele, or closely linked recessive alleles, conditioning mildew resistance. The mildew reaction type of the Ethiopian lines, Ab 6, EP 79 and Grannenlose Zweizeilige was more variable than that of the two mutant lines.
This observation accords with those of Jørgensen (1971) for Ab 6 and Unbegrannte Nackte, and Nover & Schwarzbach (1971) for SZ5139b, M66 and Unbegrannte Nackte. It thus appears that mildew resistance at the mlo locus (Jørgensen, 1972) which is common to many induced mutants, is also common to at least four barley lines obtained in Ethiopian collections. Morphological analyses, however, indicate that the Ethiopian lines investigated are closely similar so that the natural occurrence of the mutant may be more restricted than the mildew studies suggest.
References:
Jørgensen, J. H. 1971. Comparison of induced mutant genes with
spontaneous genes in barley conditioning resistance to powdery mildew.
In:
Mutation breeding for disease resistance, Vienna, IAEA.
Jørgensen, J. H. 1972. Chromosome location of locus mlo conditioning resistance to powdery mildew. Barley Genetics Newsletter 2:31-32.
Nover, I. and E. Schwarzbach. 1971. Inheritance studies with a mildew resistant barley mutant. Barley Genetics Newsletter 1:36-37.