Identification of molecular markers linked to disease resistance genes and applied marker-assisted breeding in wheat
Abstract
Selection for resistance to the fungal pathogens Mycosphaerella graminicola and Stagonospora nodorum has effectively improved the performance of wheat cultivars against these pathogens. However, the gene-for-gene nature of resistance to M. graminicola and quantitative resistance to S. nodorum necessitates the need for testing their potential durability and mapping these genes in the wheat genome. This research was conducted to identify and map quantitative trait loci (QTL) for S. nodorum resistance and to use the mapped M. graminicola resistance gene Stb2 and the previously identified S. nodorum resistance QTL Qsng.sfr-3BS to build a stably inherited linkage block in the 3BS region. Two QTL for resistance to SNB in glumes were identified in a recombinant-inbred (RI) population from the cross of the Purdue University winter wheat breeding lines P91193D1 and P92201D5: Qsng.pur-2DL.1 was inherited from P91193D1 and Qsng.pur-2DL.2 from P92201D5. Qsng.pur-2DL.1 accounted for 12.3% of the phenotypic variation for resistance in southern Indiana, and 38.1% at South Perth, Australia; Qsng.pur-2DL.2 accounted for 6.9% and 11.2% of the phenotypic variation, respectively in southern Indiana and South Perth, Australia. The RI population and parent lines were phenotyped for S. nodorum glume resistance under field conditions in F8:10 at Evansville, Vincennes, and Lafayette, Indiana, USA in 2003; in F7:9 at South Perth, Australia in 2004; and F8:10 in greenhouse grown inoculation tests at Lafayette in 2003 and 2004. In the second research project, a linkage block between Stb2 and Qsng.sfr-3Bs was developed by crossing the STB resistant line DH115 (which derived its resistance from the cultivar Veranopolis) and the SNB resistant cultivar Arina. Over five-hundred F 2 plants were screened with M. graminicola and S. nodorum in the greenhouse at West Lafayette, IN in 2005. Several lines of this population were advanced for further testing and marker analysis. The phenotype of the 03739RB1-89-3 family was consistently STB and SNB resistant. Additionally, 164 F4:5 lines from this family were genotyped with the marker Xgwm389 and both marker alleles from each parent were amplified in all 164 lines supporting the phenotypic observations that indicate a linkage block between Stb2 and Qsng.sfr-3Bs has been developed.
Degree
Ph.D.
Advisors
Ohm, Purdue University.
Subject Area
Agronomy|Plant Pathology|Plant sciences
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