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United States Department of Agriculture

Agricultural Research Service

Title: Molecular Mapping of Stb1, a Potentially Durable Gene for Resistance to Septoria Tritici Blotch in Wheat

Authors
item Adhikari, Tika
item Yang, Xiaokun - PURDUE UNIVERSITY
item Cavaletto, Jessica
item Hu, Xueyi - DOW AGRO SCIENCES
item Buechley, George - PURDUE UNIVERSITY
item Ohm, Herbert - PURDUE UNIVERSITY
item Shaner, Gregory - PURDUE UNIVERSITY
item Goodwin, Stephen

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 15, 2004
Publication Date: May 15, 2004
Citation: Adhikari, T., Yang, X., Cavaletto, J.R., Hu, X., Buechley, G., Ohm, H.W., Shaner, G., Goodwin, S.B. 2004. Molecular mapping of Stb1, a potentially durable gene for resistance to Septoria tritici blotch in wheat. Theoretical and Applied Genetics. 109(S):944-953.

Interpretive Summary: Septoria tritici blotch (STB), caused by the fungus Mycosphaerella graminicola (its asexual stage is Septoria tritici), was the most destructive disease of wheat in Indiana and adjacent states before deployment of the resistance gene Stb1 during the early 1970s. Since then, Stb1 has provided durable protection against STB in widely grown wheat cultivars. However, its chromosomal location and allelic relationships to most other STB genes are not known. To locate the Stb1 gene in the wheat genome, genetic analyses and molecular mapping were performed for two mapping populations of resistant lines containing Stb1 that were crossed to a susceptible parent. The results identified several molecular markers linked to the resistance gene, and placed its location on the long arm of wheat chromosome 5B. One molecular marker was successfully converted into a form that will be easier to use in the future. A high level of genetic variability was detected in the region near the resistance gene among diverse wheat breeding lines, so the markers should be useful for other applications. The molecular markers tightly linked to Stb1 could be useful for marker-assisted selection and for pyramiding of Stb1 with other genes for resistance to M. graminicola in wheat. Mapping this resistance gene will be of great interest to plant pathologists and wheat breeders. The molecular markers linked to Stb1 will allow this gene to be utilized immediately in wheat improvement programs around the world. Plant breeders can use the molecular markers to select for resistant individuals instead of performing inoculations, which will facilitate combining Stb1 with other STB resistance genes into a single wheat cultivar for durable resistance to M. graminicola.

Technical Abstract: Septoria tritici blotch (STB), caused by the ascomycete Mycosphaerella graminicola (anamorph Septoria tritici), was the most destructive disease of wheat in Indiana and adjacent states before deployment of the resistance gene Stb1 during the early 1970s. Since then, Stb1 has provided durable protection against STB in widely grown wheat cultivars. However, its chromosomal location and allelic relationships to most other STB genes are not known, so the molecular mapping of Stb1 is of great interest. Genetic analyses and molecular mapping were performed for two mapping populations. Bulked-segregant analysis (BSA) with random amplified polymorphic DNA (RAPD), amplified fragment length polymorphism (AFLP) and microsatellite or simple-sequence repeat (SSR) markers was conducted to identify those that were putatively linked to the Stb1 gene. Segregation analyses confirmed that a single dominant gene controls the resistance to M. graminicola in each mapping population. Two RAPD markers, G71200 and H19520, were tightly linked to Stb1 in wheat line P881072-75-1 at distances of less than 0.68 and 1.4 centimorgans (cM), respectively. In mapping population II, the most closely linked marker was SSR Xbarc74, which was 2.8 cM proximal to Stb1 on chromosome 5BL. Microsatellite loci Xgwm335 and Xgwm213 also were proximal to Stb1 at distances of 7.4 and 8.3 cM, respectively. The flanking AFLP marker, EcoRI-AGC/MseI-CTA-1, was 8.4 cM distal to Stb1. Analysis of SSR and the original RAPD primers on several 5BL deletion stocks positioned the Stb1 locus in the region delineated by chromosome breakpoints at fraction lengths 0.59 and 0.75. The molecular markers tightly linked to Stb1 could be useful for marker-assisted selection and for pyramiding of Stb1 with other genes for resistance to M. graminicola in wheat.

Last Modified: 12/20/2014
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