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United States Department of Agriculture

Agricultural Research Service

Title: Molecular Markers Linked to Genes for Resistance to Septoria Tritici Leaf Blotch in Wheat

Authors
item Goodwin, Stephen
item Adhikari, Tika

Submitted to: Wheat Genetics International Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: September 2, 2003
Publication Date: September 2, 2003
Citation: Goodwin, S.B., Adhikari, T. 2003. Molecular markers linked to genes for resistance to septoria tritici leaf blotch in wheat. In: Proceedings of the Tenth International Wheat Genetics Symposium, September 1-6, 2003, Paestum, Italy. 3:1142-1144.

Interpretive Summary: Septoria tritici leaf blotch (STB), caused by the fungus Mycosphaerella graminicola (asexual stage: Septoria tritici), is one of the most important diseases of wheat worldwide. Although at least seven major genes for resistance are known, breeding for resistance against STB is complicated by the long latent period of the disease and lack of defined tester isolates needed to transfer multiple resistance genes into a single wheat cultivar. These problems could be overcome by molecular markers linked to the resistance genes, but these are only recently available for three of the resistance genes. The map locations of the four remaining resistance genes are not known and no molecular markers are available which greatly limits their utility for plant breeding programs. To identify linkages, segregating populations of wheat were developed and screened for disease resistance and a variety of molecular markers. These analyses allowed mapping of the four previously identified resistance genes Stb1-Stb4 and a new gene, Stb8. Another potentially new gene was identified but not yet mapped. Each of the mapped resistance genes is located on a different wheat chromosome except for Stb4 and Stb5, which are both near the center of chromosome 7D. This information will be of great interest to plant pathologists, geneticists and wheat breeders. Identification of their map locations and closely linked molecular markers solves a long-standing problem and should facilitate the incorporation of these resistance genes into improved wheat cultivars worldwide.

Technical Abstract: Septoria tritici leaf blotch (STB), caused by the ascomycete fungus Mycosphaerella graminicola (asexual stage: Septoria tritici), is one of the most important diseases of wheat worldwide. Although several major genes for resistance are known, breeding for resistance against STB is complicated by the long latent period of the disease and lack of defined tester isolates needed to construct gene pyramids. These problems could be overcome by molecular markers linked to the resistance genes. To identify linked loci, segregating populations were developed and screened for polymorphism by bulked segregant analysis of amplified fragment length polymorphism and microsatellite markers. These analyses allowed mapping of the four previously identified resistance genes Stb1-Stb4 and a new gene, Stb8. Another potentially new gene was identified but not yet mapped. Three other genes were mapped in other laboratories. Each of the mapped resistance genes is located on a different wheat chromosome except for Stb4 and Stb5, which are both near the centromere on chromosome 7DS. Identification of their map locations and closely linked molecular markers solves a long-standing problem and should facilitate the incorporation of these resistance genes into improved cultivars and the construction of gene pyramids for effective control of this disease in the future.

Last Modified: 10/25/2014
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