Changes in ginsenosides and soil biodiversity related to management of ginseng replant disease****

种植者都知道，在一茬之后，不可能在同一个花园里种植人参。通常，新作物会很快死于根腐病，俗称再植病。再植疾病的持久性是以几十年来衡量的。由于再植疾病，以前没有种植过人参的合适的沙质土壤变得稀缺。据估计，未来20至30年内，安大略省不会再有更适合人参生产的土地。与此同时，前往距离家乡农场长达一小时的田地，以及转移到日益边际的土地导致产量下降，估计该行业每年要花费4000万美元。再植疾病并不像以前的人参花园中特定致病微生物持续存在那么简单。相反，越来越多的证据表明，人参花园中土壤化学和微生物生物学的关键变化发生在收获后，使人参花园不适合种植第二季人参。人参皂苷是由人参制成的化合物，为植物提供了一些药用特性。已知这些化合物会释放到土壤中，并可被土壤传播的微生物修饰。我们假设人参皂苷是由驻留的土壤微生物进行生物转化的，从而创造了一个土壤环境，组成再植疾病复合体的高毒力形式的有机体可以在其中建立。为了解决这一假设，我们将在本提案中建立人参皂苷与田间土壤、新花园人参种植期间以及最近收获的花园中微生物群之间的关系。我们还将监测特定土壤处理对田间和温室土壤微生物群和人参皂苷的影响。我们将确定与再植疾病期间根腐病水平增加有关的关键生物和人参皂苷类型，并建立分子标记，用于在土壤样本中进行常规鉴定(例如，确定一块土地是否存在再植疾病的风险)。最后，我们建议识别已识别生物的独特基因特征，并将其用作选择性管理干预的潜在目标。

It is well known by growers that after one crop, it is not possible to plant ginseng in the same gardens. Frequently, the new crop will quickly succumb to root rot disease colloquially referred to as replant disease. The persistence of replant disease is measured in decades. Due to replant disease, suitable sandy soils on which ginseng has not been grown previously are becoming scarce. It is estimated that there will not be any more suitable land for ginseng production in Ontario in the next 20 to 30 years. In the meantime, travel to fields up to an hour from their home farms and decreased yields from moving to increasingly marginal land costs the industry an estimated $40 million/yr. Replant disease is not as simple as the persistence of specific disease-causing organisms in former ginseng gardens. Instead, there is growing evidence that critical changes in both soil chemistry and microorganism biology in ginseng gardens occur post-harvest and render ginseng gardens unsuitable for a second crop of ginseng. Ginsenosides are chemical compounds made by ginseng that provide the plant with some of its medicinal properties. These compounds are known to be released into the soil, and can be modified by soil-borne microorganisms. We hypothesize that ginsenosides are biotransformed by resident soil microbes, creating a soil environment in which highly virulent forms of the organisms that comprise the replant disease complex can establish. To address this hypothesis in the present proposal we will establish the relationship between ginsenosides and the microbiome in field soil, during cultivation of ginseng in a new garden, as well as in a recently harvested garden. We will also monitor the impact of specific soil treatments on the soil microbiome and ginsenosides in the field and the greenhouse. We will identify key organisms and types of ginsenosides associated with increasing levels of root rot during replant disease and establish molecular markers for their routine identification in soil samples (e.g., to determine whether a field is at risk for replant disease). Finally, we propose to identify unique gene features of identified organisms and use them as potential targets for selective management intervention.****************