Submitted to: Proceedings of the International Sclerotinia Workshop
Publication Type: Proceedings
Publication Acceptance Date: January 22, 2003
Publication Date: January 20, 2003
Citation: Vuong, T.D., Hartman, G.L., Clough, S.J. 2003. Genetic analysis of white mold resistance using microarrays. Proceedings of the International Sclerotinia Workshop. v. January. p.18. Technical Abstract: Sclerotinia sclerotiorium is an important pathogen of soybeans in the north-central region of the United States producing the disease known as either Sclerotinia Stem Rot or White Mold. Partial resistance to this pathogen has been reported; however, understanding of the molecular basis of the resistance is limited. The recently developed cDNA microarray technology provides a promising tool to aid our search for genes involved in resistance of this disease. The powers of this tool lies in its ability to measure the expression of tens of thousands of genes simultaneously at any specific time point. We will use cDNA micro arrays (developed in the lab of Dr. Lila Vodkin at the University of Illinois) representing at least 18,000 different genes from soybean to detail the genetic responses of soybeans to this pathogen and to search for specific genes governing soybean resistance. We have completed one round of inoculations using the susceptible cultivar Williams 82 and the resistant plant introduction PI194639. We inoculated the freshly cut end of stems of 4-week-old plants with agar plugs containing a fresh culture of S. Sclerotinia or with sterile agar control plugs. The top 1.5 inches of inoculated or mock inoculate stems was collected at 0, 1, 3, 6, 18, 30, and 48 hours post inoculation and immediately frozen in liquid nitrogen and stored at -80 degrees C. Total RNA was isolated from these tissues by Trizol extraction and will be labeled with fluorescent dUTP to determine gene expression profiles using the soybean micro arrays. Genes that show strong correlation with resistance will be converted into molecular markers to determine if they are associated with known QTLs. For mapping purposes, one hundred and fifty F4 plants of a resistant x susceptible cross were grown in the greenhouse during the summer of 2002 for seed increases. These recombinant inbred lines were then planted in the greenhouse in the winter 2002 for scoring their resistance/susceptible phenotypes using the cut-stem inoculation method.