|Adhikari, Tika -|
|Gurung, Suraj -|
|Hansen, Jana M -|
Submitted to: The Plant Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 5, 2012
Publication Date: February 7, 2012
Repository URL: http://riley.nal.usda.gov/nal_web/digi/submission.html
Citation: Adhikari, T.B., Gurung, S., Hansen, J., Jackson, E.W., Bonman, J.M. 2012. Association mapping of quantitative trait loci responsible for resistance to Bacterial Leaf Streak and Spot Blotch in spring wheat landraces. The Plant Genome. 5:1-16. doi:10.3835/plantgenome2011.12.0032. Interpretive Summary: Bacterial leaf streak and spot blotch are two important disease of wheat. Planting resistant wheat varieties is the best way to manage these two diseases, but relatively little is known about resistance to these diseases. In this study we applied a technique called ‘association mapping’ to discover locations in the wheat genome where resistance is found. This information will eventually help plant breeders efficiently produce new wheat varieties resistant to the two diseases.
Technical Abstract: Bacterial leaf streak (BLS), caused by Xanthomonas translucens pv. undulosa, and spot blotch (SB), caused by Cochliobolus sativus are two major diseases of wheat (Triticum aestivum L.). Planting resistant cultivars is the best approach to manage these diseases and identifying new sources of resistance would benefit resistance breeding efforts. Although linkage analysis of bi-parental populations has identified a few quantitative trait loci (QTL), association mapping (AM) could be an efficient strategy to identify novel resistance in germplasm collections for use in wheat improvement. The main objective of this study was to use the combination of AM and 832 polymorphic Diversity Array Technology (DArT) markers to identify genomic regions associated with resistance to BLS and spot blotch in 566 spring wheat landraces of diverse origin. Infection types of BLS were rated on flag leaves infiltrated with X. translucens pv. undulosa and for SB on seedlings inoculated with C. sativus in the greenhouse. Association analysis revealed five DArT markers located on chromosomes 1A, 4A, 4B, 6B and 7D that were significantly associated with resistance to BLS. Similarly, four DArT markers located on chromosomes 1A, 3B, 7B and 7D were associated with resistance to SB. Two markers located on chromosomes 3B and 7D correspond to the previously mapped QTL conferring resistance to SB, while the remaining QTL appeared to be novel. Some of the DArT markers linked to the resistance phenotypes in this study also were mapped to the same genetic regions where QTL for yellow rust, leaf rust, and powdery mildew resistance have been previously mapped. These results suggest that AM was effective to provide a platform for discovery of novel genes for resistance to the two diseases, which could be validated and utilized in wheat breeding programs.