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TECHNICAL SESSION: Soilborne pathogen interactions

Studying the In vitro interactions between Fusarium virguliforme and soil-borne nematodes using fluorescent microscopy
Mitchell Roth - Michigan State University. Martin Chilvers- Michigan State University

Soybean cyst nematode (SCN) and Fusarium virguliforme are major threats to soybean production throughout the U.S. Management strategies for both pathogens are similar and include using genetically resistant varieties, diverse crop rotations, and seed treatments containing a nematicide or fungicide. Fusarium virguliforme causes soybean sudden death syndrome (SDS) by infecting root tissues, colonizing vascular tissues, and releasing protein effectors and toxins into soybean xylem, inducing foliar SDS symptoms. Though SCN cannot cause SDS, many studies have identified a strong positive correlation between SDS severity and SCN abundance, though the role of SCN in SDS development remains unknown. In this study, we explored the interactions between F. virguliforme and the model nematode Caenorhabditis elegans and the soybean cyst nematode Heterodera glycines. Fusarium virguliforme is able to colonize dead and immobilized nematodes, suggesting that F. virguliforme is an excellent saprophyte and may be able to use nematodes as a nutrient source, which could increase F. virguliforme inoculum. However, colonization of living mobile nematodes was not observed, indicating that F. virguliforme is not vectored into soybean roots by nematodes. However, co-infections of soybean roots by both pathogens may affect the expression of F. virguliforme effectors, which was also explored in this study. Overall, these results suggest that successful SCN management may also lead to improved SDS management.