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Screening soybean and corn root colonization by a Fusarium virguliforme natural population

Judy Chen: Michigan State University

<div>In the United States, soybean sudden death syndrome is caused by the ascomycete <em>Fusarium</em> <em>virguliforme</em> (<em>Fv</em>). Previous screenings of <em>Fv </em>isolates have revealed differences in aggressiveness on soybean; however, it remains unknown if isolate aggressiveness persists on alternate hosts. In the current study, we asked if corn, commonly rotated with soybean and an asymptomatic host for <em>Fv</em>, can be colonized by natural populations of <em>Fv</em>. In 2016, isolates were collected from soybean roots in a field naturally infested with <em>Fv</em>, and nine were evaluated for their ability to infect both soybean and corn in a growth pouch based assay. Soybean and corn seedlings, either individually inoculated with<em> Fv </em>macroconidia from nine field isolates or <em>Fv </em>isolate<em> </em>Mont-1. After 14 days post inoculation, <em>in-planta </em>pathogen growth was assessed using trypan blue staining of roots. Further, root samples were collected for DNA extraction, and real time qPCR assay assessed <em>Fv</em> DNA quantities. Over the two-week interval, symptoms developed on the soybean roots but not on corn roots. However, staining revealed <em>Fv</em> mycelia growth upon both the soybean and corn roots. The first biological repeat showed a trend of 100-fold reduction of corn to soybean<em> Fv</em> DNA quantities, but different isolate colonization levels were detected within each plant type. Ongoing experiments will uncover if <em>Fv </em>has differing patterns of colonization that is consistent in both corn and soybean roots from a natural population.</div>