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Title: MIAG12: A Triticum timopheevii-derived powdery mildew resistance gene in common wheat on chromosome 7AL

Author
item MAXWELL, J - North Carolina State University
item LYERLY, J - North Carolina State University
item Cowger, Christina
item Marshall, David
item Brown-Guedira, Gina
item MURPHY, J - North Carolina State University

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2009
Publication Date: 9/18/2009
Citation: Maxwell, J.J., Lyerly, J.H., Cowger, C., Marshall, D.S., Brown Guedira, G.L., Murphy, J.P. 2009. MIAG12: A Triticum timopheevii-derived powdery mildew resistance gene in common wheat on chromosome 7AL. Theoretical and Applied Genetics. 119:1489–1495.

Interpretive Summary: Wheat powdery mildew is an economically important disease in cool and humid 2 environments. Powdery mildew causes yield losses as high as 48 percent through a reduction in 3 tiller survival, kernels per head and kernel size. Race-specific host resistance is the most 4 consistent, environmentally friendly and economical method of control. The wheat (Triticum 5 aestivum L) germplasm line NC06BGTAG12 possesses genetic resistance to powdery mildew 6 introgressed from the AAGG genome tetraploid T. timopheevii subsp. armeniacum. Phenotypic 7 evaluation of F3 families derived from the crosses NC06BGTAG12 / ‘Jagger’ and phenotypic 8 evaluation of an F2 population from the crosses NC06BGTAG12 / ‘Saluda’ indicated the 9 resistance in the germplasm line was controlled by a single dominant gene. Bulk segregant 10 analysis revealed SSR markers specific for chromosome 7AL segregated with the resistance 11 gene. The SSR markers Xwmc273 and Xwmc346 mapped 8.3 cM distal and 6.6 cM proximal, 12 respectively, in NC06BGTAG12 / Jagger. The multiallelic Pm1 locus maps to this region of 13 chromosome 7AL. A detached leaf test with ten differential powdery mildew isolates indicated 14 that the resistance gene in NC06BGTAG12 was different from all designated alleles at the Pm1 15 locus. Phenotypic evaluation of 967 F2 individuals in the cross NC06BGTAG12 / ‘Axminster’ 16 (Pm1a) confirmed that the NC06BGTAG12 resistance gene was within 11.1 cM (p=0.05) of the 17 Pm1 locus. Further linkage and allelism tests with the five other temporarily designated genes in 18 this very complex region will be required before giving this gene a permanent designation. At 19 this time the gene is given the temporary gene designation MlAG12.

Technical Abstract: Wheat powdery mildew is an economically important disease in cool and humid 2 environments. Powdery mildew causes yield losses as high as 48 percent through a reduction in 3 tiller survival, kernels per head and kernel size. Race-specific host resistance is the most 4 consistent, environmentally friendly and economical method of control. The wheat (Triticum 5 aestivum L) germplasm line NC06BGTAG12 possesses genetic resistance to powdery mildew 6 introgressed from the AAGG genome tetraploid T. timopheevii subsp. armeniacum. Phenotypic 7 evaluation of F3 families derived from the crosses NC06BGTAG12 / ‘Jagger’ and phenotypic 8 evaluation of an F2 population from the crosses NC06BGTAG12 / ‘Saluda’ indicated the 9 resistance in the germplasm line was controlled by a single dominant gene. Bulk segregant 10 analysis revealed SSR markers specific for chromosome 7AL segregated with the resistance 11 gene. The SSR markers Xwmc273 and Xwmc346 mapped 8.3 cM distal and 6.6 cM proximal, 12 respectively, in NC06BGTAG12 / Jagger. The multiallelic Pm1 locus maps to this region of 13 chromosome 7AL. A detached leaf test with ten differential powdery mildew isolates indicated 14 that the resistance gene in NC06BGTAG12 was different from all designated alleles at the Pm1 15 locus. Phenotypic evaluation of 967 F2 individuals in the cross NC06BGTAG12 / ‘Axminster’ 16 (Pm1a) confirmed that the NC06BGTAG12 resistance gene was within 11.1 cM (p=0.05) of the 17 Pm1 locus. Further linkage and allelism tests with the five other temporarily designated genes in 18 this very complex region will be required before giving this gene a permanent designation. At 19 this time the gene is given the temporary gene designation MlAG12.