Soil Rhizome Metabarcoding of Diseased and Healthy American Ginseng Cultivated in Maryland and Wisconsin

One of the greatest challenges faced by ginseng producers is control of fungal pathogens which adversely affects harvest yields and is a contributing factor to replant failure syndrome which prevents continuous monoculture of American Ginseng. The goal of this project was to survey the bacterial soil microbiome of healthy versus diseased American Ginseng grown in North America. Our hope is to eventually identify soil microbes with anti-fungal properties associated with healthy plants that could be developed into an organic fungicide. Soil associated with healthy and diseased plants were collected from commercial farms in Garett County, Maryland and Marathon County, Wisconsin. Environmental DNA metabarcoding was used to compare the bacterial and fungal microbiomes of healthy versus diseased plants from both locations. The most common bacteria occurred within the phylum Proteobacteria, Firmicutes, and Bacteroidota and the most common fungi occurred within Ascomycota, Basidiomytoca, Mortierellomycota and Glomeromycota. Alpha- and Beta- diversity comparisons identified statistically significant differences between the locations. Comparison of soil microbes associated with diseased versus healthy plants demonstrated inconsistencies between the two sites. Diseased plants in Wisconsin had significantly lower bacterial and fungal alpha-diversity whereas no differences in diversity were detected from the Maryland samples. Community analyses (beta-diversity) of the Maryland site revealed a significant difference in the bacterial composition of soils associated with healthy versus diseased plants but not fungi. Conversely, there was a significantly different assemblage of fungi in healthy versus diseased associated soils from the Wisconsin site, but none were detected for bacteria. Our results when compared to previous metabarcoding studies suggest there is little congruence between the soil microbiomes associated with cultivated ginseng and that we are still in the early stages of ginseng soil rhizome exploration.