Submitted to: Proceedings of the International Sclerotinia Workshop
Publication Type: Proceedings
Publication Acceptance Date: April 1, 2005
Publication Date: June 1, 2005
Citation: Miklas, P.N. 2005. Advances to achieving resistance to sclerotinia. Proceedings of the 13th International Sclerotinia Workshop, Modesto, CA, June 12-15, 2005. p. 4. Technical Abstract: Host resistance is becoming an ever-increasing component of integrated strategies for control of diseases caused by Sclerotinia sclerotiorum. Partial resistance in bean, canola, soybean, sunflower, and other crops is quantitatively inherited with low to moderate heritability indicating that breeding for improved resistance is possible but will be difficult. Genomics and QTL analyses are leading to a better understanding of the quantitative resistance present in different crop species. In bean, major QTL for resistance have been identified and marker-assisted selection (MAS) has been used successfully to transfer the QTL into susceptible lines. Combining resistance QTL from different sources via MAS and recurrent selection is the current breeding method of investigation in bean, soybean and other crops for increasing the level of physiological resistance in present day cultivars. Even with MAS as a tool, breeding for improved resistance will be difficult, and the resistance developed still only likely to be partially effective and subject to breakdown under heavy disease pressure. So in addition to manipulating natural resistance available within the crop, researchers have been exploring other means for developing resistance. Interspecific crosses with related species possessing greater levels of resistance show promise for improving resistance in common bean and sunflower, but the introgression of such resistance requires a long-term breeding commitment to recover the resistance in adapted phenotypes. Some resistance in scarlet runner bean has shown single gene inheritance, but such resistance is the exception and has not been deployed in a common bean cultivar yet. GMOs in sunflower and soybean with the Oxalate Oxidase (OxO) gene exhibit improved resistance. However, GMOs with OxO, in addition to general consumer prejudices against GMOs, face proprietary and profitability roadblocks which prevent commercialization. Nonetheless, due to the paucity of natural resistance to Sclerotinia available for most crops, continuous exploration of new methods and technologies for developing resistance to Sclerotinia is needed. Genomic research is enabling identification of candidate genes in the resistance response which may lead to new strategies for molecular engineering improved resistance to Sclerotinia in the future.