Effect of Soil and Root Extracts on the Innate Immune Response of American Ginseng () to Root Rot Caused by .

shows much higher mortality to root rot when grown in soil previously planted with ginseng than in soil not previously planted with ginseng, which is known as ginseng replant disease. Treatment of ginseng roots with methanol extracts of previous ginseng soils significantly increased root lesion sizes due to compared to roots treated with water or methanol extracts of ginseng roots or non-ginseng soils. Inoculation of water-treated roots with increased expression of a basic chitinase 1 gene (), neutral pathogenesis-related protein 5 gene () and pathogenesis-related protein 10-2 gene (), which are related to jasmonic acid (JA), ethylene (ET) or necrotrophic infection, and also increased expression of an acidic β-1-3-glucanase gene (), which is related to salicylic acid (SA). Infection did not affect expression of a cysteine protease inhibitor gene (). Following infection, roots treated with ginseng root extract mostly showed similar expression patterns as roots treated with water, but roots treated with previous ginseng soil extract showed reduced expression of , , and , but increased expression of . Methanol-soluble compound(s) in soil previously planted with ginseng are able to increase root lesion size, suppress JA/ET-related gene expression and trigger SA-related gene expression in ginseng roots during infection, and may be a factor contributing to ginseng replant disease.