Submitted to: The Plant Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2009
Publication Date: 8/1/2009
Citation: Calla, B., Vuong, T., Radwan, O., Hartman, G.L., Clough, S.J. 2009. Gene Expression Profiling Soybean Stem Tissue Early Response to Sclerotinia sclerotiorum and in Silico Mapping in Relation to Resistance Markers. The Plant Genome. 2:149-166.
Interpretive Summary: White mold is a disease of many crop plants grown during cool, moist weather. In many crops, like soybean, it is difficult to control, and complete genetic resistance does not exist. However, plants with partial resistance are available for breeding programs and for researchers to study possible resistance mechanisms. We used such a line to study gene expression changes between partially resistant and highly susceptible soybean lines. Our analysis identified over a thousand genes responding to inoculation, regardless of resistance level, and 105 genes that were differentially expressed between partially resistant and susceptible types. This gene list provides insight to how soybean responds to this aggressive pathogen and provides possible clues to resistance mechinisms. Additionally, we show how one can map these differentially expressed genes in the soybean genome to identify known chromosomal areas associatied with white mold resistance. These results will be of interest to all scientists studying host plant resistance.
Technical Abstract: White mold, caused by Sclerotinia sclerotiorum (Lib) de Bary, can be a serious disease of crops grown under cool moist environments. In many plants, like soybean [Glycine max (L.) Merr.], complete genetic resistance does not exist. To identify possible genes involved in defense against this pathogen, and to determine possible physiological changes that occur during infection, a microarray screen was conducted using stem tissue to evaluate changes in gene expression between partially resistant and susceptible soybean genotypes at 8 and 14 hours post inoculation. RNA from 15 day old inoculated plants was labeled and hybridized to soybean cDNA microarrays. ANOVA identified 1270 significant genes from the comparison between time points and 105 genes from the comparison between genotypes. Selected genes were classified into functional categories. The analyses identified changes in cell-wall composition and signaling pathways, as well as suggesting a role for anthocyanin and anthocyanidin synthesis in the defense against S. sclerotiorum. In-silico mapping of both the differentially expressed transcripts and of public markers associated with partial resistance to white mold, provided evidence of several differentially expressed genes being closely positioned to white mold resistance markers, with the two most promising genes encoding a PR-5 and anthocyanidin synthase.