Temporal dynamics of soybean root colonization by Fusarium virguliforme
J. WANG (1), J. L. Jacobs (1), M. I. Chilvers (1). (1) Michigan State University, East Lansing, MI, U.S.A.
Soybean sudden death syndrome, caused by <i>Fusarium virguliforme</i>, is one of the most devastating diseases in the Midwest. Selection of resistant soybean varieties is the most effective disease control strategy. Separate genetic loci control foliar and root rot resistance to sudden death syndrome in soybean. The ability to rapidly and accurately phenotype root resistance to <i>F. virguliforme</i> colonization would be extremely valuable for soybean breeding and epidemiological studies. Roots were collected from soybean plants from the V3 growth stage every two weeks until after harvest. Root samples were ground and DNA was extracted for <i>F. virguliforme</i> quantification using a real-time qPCR assay. Field experiments were conducted at two locations, utilizing two susceptible and two partially resistant soybean cultivars. <i>Fusarium virguliforme</i> was detected at the initial V3 sampling time point in both locations; however, foliar symptoms were not observed until plants reached R1 growth stage. A general trend of increasing <i>F. virguliforme</i> DNA concentration was observed in roots overtime, with a decrease in concentration noted at the R5 growth stage. Cultivars demonstrated distinct DNA accumulation rates of <i>F. virguliforme</i>. Partially resistant cultivars demonstrated minimal or no foliar disease symptoms throughout the trial; however, the <i>F. virguliforme</i> DNA concentrations among cultivar root systems were only significantly different (<i>p</i><0.05) at V3 and post-harvest sampling times.
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