Resistance to powdery mildew in selections from Tunisian landraces of barley

• Published in: Plant breeding Vol. 118; no. 6; pp. 503 - 509
• Main Authors: Czembor, J. H., Johnston, M. R.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.12.1999; Blackwell
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Erysiphe graminis; Fundamental and applied biological sciences. Psychology; Generalities. Genetics. Plant material; Genetic resources, diversity; Genetics and breeding of economic plants; Hordeum vulgare; land-races; Pest resistance; Plant material; Plant pathogens; resistance genes; Varietal selection. Specialized plant breeding, plant breeding aims; Tunisia; North Africa; Africa; Monocotyledones; Plant pathogen; Hordeum vulgare; Genetic resource; Landrace(plant); Genetic determinism; Cereal crop; Fungus resistance; Fungi; Screening; Microorganism resistance; Dominance recessiveness; Sensitivity resistance; Gramineae; Genetic improvement; Angiospermae; Selection criterion; Ascomycetes; Spermatophyta; Erysiphe graminis f. hordei; Intraspecific comparison; Thallophyta
• ISSN: 0179-9541; 1439-0523
• DOI: 10.1046/j.1439-0523.1999.00382.x

Two‐hundred and thirty‐two accessions of barley landraces collected from Tunisia were screened for resistance to powdery mildew. A number of race‐specific genes were detected using the detached leaf technique. Among the 232 accessions tested, 169 were susceptible to powdery mildew, 20 were resistant and 43 showed differential reactions to the three isolates of powdery mildew used. An attempt was made to determine the number of genes, the types of gene, the types of gene action and the gene loci in 20 resistant accessions. Three types of cross were made: (1) the accessions were crossed to the susceptible variety ‘Pallas’, (2) the accessions were crossed with ‘Pallas’ isolines, and (2) accessions with identical powdery mildew reaction patterns were intercrossed. Three isolates of Erysiphe graminis f. sp. hordei were used: Bzm‐1, KM 18‐75, R13C. A number of different resistance genes were detected among the 19 resistant accessions. Surprisingly, segregation indicating single genes only were detected with the isolates used. Some of these genes could be associated with loci already known. In 19 cases a dominant and in one a recessive mode of inheritance was detected. The recessive gene was not located at the mlo locus. This investigation represents the first systematic study of race‐specific genes for powdery mildew resistance in Tunisian landraces. The newly identified sources of resistance may be used in many strategies of breeding for disease resistance.