Submitted to: Proceedings of the International Sclerotinia Workshop
Publication Type: Abstract Only
Publication Acceptance Date: December 21, 2004
Publication Date: January 21, 2005
Citation: Vuong, T., Hartman, G.L., Clough, S.J. 2005. Searching for defense-related gene candidates from soybean that confer partial resistance to sclerotinia [abstract]. Proceedings of the International Sclerotinia Workshop. p. 53. Technical Abstract: We are using cDNA microarrays to aid in the search for genes related to defense against Sclerotinia disease in soybean. We have completed two rounds of inoculations using the susceptible cultivar Williams 82 and the resistant plant introduction PI194639. Inoculated and uninoculated resistant and susceptible plants were analyzed at 0, 6, 18, and 48 hours post inoculation. This short time course indicated that the activation of enzymes involved in phytoalexin production was already going strong by 18 hours. Therefore, to identify genes involved in early signalling of defenses, we focused more deeply on the 6 hour time point. Because differential gene expression at 6 hour was somewhat weak and less consistent, we increased our number of reps to 3 independent inoculations and involved a statistical ANOVA calculation to assist in the identification of genes that were most significantly up or down regulated upon pathogen infection. To summarize our current microarray results, we have identified several hundred genes as candidates for marker development and analysis of association with resistance in PI194639. The ANOVA of the 6 hour time point data revealed that 58 genes were significantly (p'0.001) differentially expressed between PI194639 and Williams 82. These changes in expression at 6 hour post inoculation were seen when comparing PI194639 inoculated to not inoculated (26 genes), PI194639 inoculated versus Williams 82 inoculated (27 genes) and PI194639 not inoculated versus Williams 82 not inoculated (22 genes). Due to overlap, the total number of differentially expressed genes at 6 hours post inoculation was 58, which can be roughly broken down into: 27 unknown genes, 8 DNA or RNA binding factors, and 23 miscellaneous genes.