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Screening A Soybean Cyst Nematode Mycobiome for Potential Natural Antagonists in Search of Biological Control Agents and Biopesticides

Deepak Rajendran: Plant Pathology, University of Minnesota

<div>Soybean is the second most important crop for the United States, and Soybean Cyst Nematodes (SCN), its most important pathogen, can cause upto 40% yield loss with no visible above-ground symptoms until later in the season. Effective chemical control agents and fumigants against SCN are detrimental to the environment and animal safety, and hence banned. Crop rotation and genetics are current solutions to manage the disease, while not sustainable. In this light, Biological control agents, especially fungal agents that can sporulate and withstand harsh winters of major soybean states of USA, are attractive and promising options. We have isolated about 6000 fungal samples associated with SCN cysts over 3 years and 6 total crop sequences. These isolates were then grouped together as morphotypes based on their appearance on potato dextrose agar, and representatives from each morphotype were identified using their ITS1 barcoding region and BLAST search against NCBI database. The morphotypes were further collapsed into 321 clusters based on 99% similarity in ITS1 barcoding region using uclust function in qiime. Representatives from each cluster were examined for their ability to withstand freeze-thaw, infect clean SCN cysts and eggs, produce spores, and toxic metabolites that can interfere with SCN egg-hatch and mobility. Many <em>Nectriaceae</em> clusters including <em>Fusarium, Ilyonectria</em> and <em>Cylindrocarpon</em> exhibit high parasitism as well as produce metabolites that inhibit egg hatching upto 90% with respect to control. A few candidate biocontrol agents were identified for greenhouse trials while chemically prospecting those producing toxic metabolites for safe bionematicides.</div>