• Using RNASeq, we found about 200 F. virguliforme genes that are produced at higher levels in toxin-producing cultures vs. toxin-free cultures. These genes indicate possible pathogenicity pathways used by this fungus to cause SDS. The genes are candidates for toxin-synthesis, or SDS symptom development; some are predicted to confer resistance to toxins or control the regulation of other genes.
• Using RNAseq of partially resistant and susceptible soybean genotypes, we created a complete database of the soybean genes that are overexpressed in root and leaf tissues in response to F. virguliforme toxins. This dataset indicates possible mechanisms employed by soybeans to reduce damage by F. virguliforme toxins, and will be useful in developing soybean lines with improved resistance to SDS.
• In flooding experiments, we found that flooding duration affects severity of SDS root rot and leaf symptoms, as well as density of F. virguliforme in soil. Short duration flooding (8h per week or 3 days continuous flooding) increased SDS severity compared to no flooding. This was probably due to reduced root weight caused by flooding stress. In contrast, long duration flooding (5 or 7 days continuous flooding) generally reduced SDS severity and F. virguliforme density in soil. The effect of flooding on SDS therefore depends on the relative level of stress on the plant and pathogen components of the SDS disease triangle. This information helps to understand how waterlogged soils affect SDS development in the field.