Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2009
Publication Date: 6/1/2009
Citation: Rauscher, G.M., Hayes, R.J., Simko, I. 2009. QTL mapping of resistance to Powdery Mildew in lettuce. Phytopathology 99:S107.
Technical Abstract: Erysiphe cichoracearam causes powdery mildew on most compositae including lettuce and chicory. Variation in susceptibility has been documented both in cultivated lettuce and wild relatives. Little is known about the genetic architecture of resistance to the pathogen, but monogenic resistance has been reported. We have used a set of recombinant inbred lines between L. sativa var. Salinas and L. serriola to map quantitative resistance to powdery mildew through the application of newly developed genomic and EST-SSR markers distributed along the lettuce genome. Quantitative assessment of disease development took place in the greenhouse in Salinas, CA during the winter of 2008-2009 using a 0-5 scoring scale. Disease development was faster in L. serriola than in L. sativa. Phenotypic data were normally distributed, indicative of a quantitative trait. A framework map was obtained from the Compositae genome project database and our SSR markers were assigned to known linkage groups. Resistance data were added both as disease assessment at scoring dates and as an approximation of AUDPC. A QTL for resistance was located to linkage group 2 associated with the EST-SSR marker SML22, it explains about 15% of the variation. QTLs for susceptibility were found in linkage groups 1, 4 and 8 making them interesting areas for further research.