Molecular marker analysis of powdery mildew resistance in barley
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Molecular marker analysis of powdery mildew resistance in barley Saghai Maroof, M. A., Q. Zhang and R. M. Biyashev. 1994. Theor. Appl. Genet. 88:733-740. [b]SUMMARY Powdery mildew, caused by Eryisphe graminis f. sp. hordei, is one of the most important diseases of barley (Hordeum vulgare). A number of loci conditioning resistance to this disease have been reported previously. The objective of this study was to use molecular markers to identify chromosomal regions containing genes for powdery mildew resistance and to estimate the resistance effect of each locus. A set of 28 F1 hybrids and eight parental lines from a barley diallel study were inoculated with each of five isolates of E. graminis. The parents were surveyed for RFLPs at 85 marker loci that cover about 1100 cM of the barley genome. The RFLP genotypes of the F1s were deduced from those of the parents. A total of 27 loci, distributed on six of the seven barley chromosomes, detected significant resistance effects to at least one of the five isolates. Almost all the chromosomal regions previously reported to carry genes for powdery mildew resistance were detected, plus the possible existence of one additional locus on chromosome 7. The analysis indicated that additive genetic effects are the most important component in conditioning powdery mildew resistance. However, there is also a considerable amount of dominance effects at most loci, and even overdominance is likely to be present at a number of loci. These results suggest that quantitative differences are likely to exist among alleles even at loci which are considered to carry major genes for resistance, and minor effects may be prevalent in cultivars which are not known to carry major genes for resistance. Key words Restriction fragment length polymorphism (RFLP), Hordeum vulgare, Quantitative resistance, Erysiphe graminis f. sp. hordei, diallel