Comparative analysis of rhizosphere soil physiochemical characteristics and microbial communities between rusty and healthy ginseng root

Abstract

Ginseng rusty root (GRR) symptom is one of the primary diseases of ginseng. There has been a problem of ginseng rusty root, leading to a severe decline in the quality of ginseng. To clarify the relationship between root symptoms of ginseng rust and soil, the physical and chemical properties, enzyme activity, community structure and microbial diversity of GRR and healthy ginseng (HG) rhizosphere soil were analyzed and compared. The pH and redox potential (Eh) of GRR soil decreased, and the contents of total phosphorus (TP), available phosphorus (AP), and available potassium (AK) decreased. The activity of catalase and phosphatase and invertase was lower than that of HG groups. Besides, the microbial community of GRR rhizosphere soil changes much, and its abundance and diversity are significantly reduced. The community structure of GRR rhizosphere soil also shows apparent differences, and the samples of the HG group gathered together, and the samples of the GRR group were dispersed. In general, GRR was closely associated with decreases in soil pH and Eh; decreases in TP, AP, and AK; decreases in the activity of several enzymes. Additionally, it is strongly associated with an increase in pathogenic microorganisms such as Ilyonectria and a reduction of beneficial microorganisms such as Tremellomycetes Acidobacteria subgroup 6 and Gemmatimonadetes.

Figure 1

Chemical properties of soil. (A) Soil redox potential; (B) pH. HG: healthy ginseng soil groups; GRR: ginseng rusty root symptom soil groups. Letters indicate significant differences among different soil samples by ANOVA at P ** < 0.01 versus HG group (n = 6 in each group).

Figure 2

Nutrient content of soil. (A) Soil organic matter; (B) total nitrogen; (C) total phosphorus; (D) available nitrogen; (E) available phosphorus; (F) available potassium. HG: healthy ginseng soil groups; GRR: ginseng rusty root symptom soil groups. Letters indicate significant differences among different soil samples by ANOVA at P * < 0.05, P ** < 0.01 versus HG group (n = 6 in each group).

Figure 3

Soil enzyme activity. (A) Catalase activity; (B) invertase activity; (C) urease activity; (D) phosphatase activity. HG: healthy ginseng soil group; GRR: ginseng rusty root symptom-high soil group. Letters indicate significant differences among different soil samples by ANOVA at P ** < 0.01 versus HG group (n = 6 in each group).

Figure 4

Microbial richness and diversity. (A) Bacteria; (B) fungi. HG: healthy ginseng soil group; GRR: ginseng rusty root symptom soil group. Letters indicate significant differences among different soil samples by ANOVA at P * < 0.05, P ** < 0.01 versus HG group (n = 6 in each group).

Figure 5

Microbial principal coordinate analysis (PCoA). (A) Bacteria Jaccard distance; (B) bacteria Bray–Curtis distance; (C) fungi Jaccard distance; (D) fungi Bray–Curtis distance. HG: healthy ginseng soil group; GRR: ginseng rusty root symptom soil group (n = 6 in each group).

Figure 6

Venn diagrams of ASVs among soil samples. (A) Bacteria; (B) fungi. HG: healthy ginseng soil group; GRR: ginseng rusty root symptom soil group.

Figure 7

Bacterial abundance and biomarkers. (A) Heatmap of the 50 most abundant genera in soil samples; (B) histogram of LDA effect value of the histogram of LDA effect value of differentially abundant taxa. HG: healthy ginseng soil group; GRR: ginseng rusty root symptom soil group.

Figure 8

Fungi abundance and biomarkers. (A) Heatmap of the 50 most abundant genera in soil samples; (B) histogram of LDA effect value of differentially abundant taxa. HG: healthy ginseng soil group; GRR: ginseng rusty root symptom soil group.

Figure 9

Redundancy analysis (RDA) of soil samples; (A) RDA plots of bacteria in soil samples; (B) RDA plots of fungi in soil samples. HG: healthy ginseng soil group; GRR: ginseng rusty root symptom soil group.