Resistance of wheat to septoria tritici blotch (Mycosphaerella graminicola) and associations with plant ideotype and the 1BL−1RS translocation |
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Authors: | L. S. Arraiano P. A. Brading F. Dedryver J. K. M. Brown |
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Affiliation: | Disease and Stress Biology Department, John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, UK;and;UMR INRA-Agrocampus, Amélioration des Plantes et Biotechnologie Végétale, BP 35327-35653 Le Rheu Cedex, France |
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Abstract: | Septoria tritici blotch (STB) is a major disease of wheat, reaching epidemic proportions in many parts of the world. In several studies, taller, later-maturing cultivars have had lower disease levels. This study was undertaken to investigate the genetic associations of natural field infection by STB with disease-escape mechanisms related to heading date and height components, mainly leaf spacing, in a population where height and maturity are not controlled by major genes. In field trials of a single seed-descent population of a cross between two nonsemi-dwarf cultivars, Apollo (with strong partial resistance to STB) and Thésée (susceptible), conducted over 3 years, there was a negative correlation between STB and heading date. There was no correlation between STB and distance from stem base to leaf 2; and there was an unexpected positive correlation between STB and distance from flag leaf to leaf 2, which contradicted the so-called 'ladder effect' postulated in STB epidemiology. No effect was detected of the presence of the 1BL−1RS translocation on STB levels. The largest single contributor to variation in STB levels was genetic variation between the progeny lines, and the narrow-sense heritability was 42%. These results suggest that breeders can select for STB resistance alongside optimal stature within the range of height which is adaptive in a particular environment. |
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Keywords: | 1BL−1RS translocation genetics of resistance Mycosphaerella graminicola plant ideotype septoria tritici blotch wheat |
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