The relationship between shifts in the rhizosphere microbial community and root rot disease in a continuous cropping American ginseng system

Abstract

The root rot disease causes a great economic loss, and the disease severity usually increases as ginseng ages. However, it is still unclear whether the disease severity is related to changes in microorganisms during the entire growing stage of American ginseng. The present study examined the microbial community in the rhizosphere and the chemical properties of the soil in 1–4-year-old ginseng plants grown in different seasons at two different sites. Additionally, the study investigated ginseng plants' root rot disease index (DI). The results showed that the DI of ginseng increased 2.2 times in one sampling site and 4.7 times in another during the 4 years. With respect to the microbial community, the bacterial diversity increased with the seasons in the first, third, and fourth years but remained steady in the second year. The seasonal changing of relative abundances of bacteria and fungi showed the same trend in the first, third, and fourth years but not in the second year. Linear models revealed that the relative abundances of Blastococcus, Symbiobacterium, Goffeauzyma, Entoloma, Staphylotrichum, Gymnomyces, Hirsutella, Penicillium and Suillus spp. were negatively correlated with DI, while the relative abundance of Pandoraea, Rhizomicrobium, Hebeloma, Elaphomyces, Pseudeurotium, Fusarium, Geomyces, Polyscytalum, Remersonia, Rhizopus, Acremonium, Paraphaeosphaeria, Mortierella, and Metarhizium spp. were positively correlated with DI (P < 0.05). The Mantel test showed that soil chemical properties, including available nitrogen, phosphorus, potassium, calcium, magnesium, organic matter, and pH, were significantly correlated to microbial composition. The contents of available potassium and nitrogen were positively correlated with DI, while pH and organic matter were negatively correlated with DI. In summary, we can deduce that the second year is the key period for the shift of the American ginseng rhizosphere microbial community. Disease aggravation after the third year is related to the deterioration of the rhizosphere microecosystem.

Effects of different nitrogen forms and concentration combinations on American ginseng seedling growth

“…Overall, the present study demonstrates that the growth-promoting effect of the combined application of the different forms of N was considerably higher than that of the addition of any single form of N. Moreover, treatment with high nitrate and low ammonium concentrations combined with amino acids (tyrosine and glycine), at levels that are difficult to restore in AGcultivated soils, had a significant effect on the growth of AG seedlings. Our findings and those of previous studies suggest that N nutrition may affect disease resistance in plants (Bi et al, 2023). Therefore, it was speculated that environmental stress and pathogen infection of P. quinquefolium during the growth period would be affected by N addition.…”

Integrated metagenomics and metabolomics analysis reveals changes in the microbiome and metabolites in the rhizosphere soil of Fritillaria unibracteata

“…Monocultures are considered likely to lead to pathogen accumulation and deterioration of soil conditions (Liu et al, 2018). Monocultures can also cause continuous cropping disorders, as observed for Panax quinquefolius, Pinellia ternata, and Lilium lancifolium (Dai et al, 2022;Li et al, 2022;Bi et al, 2023). The soil microbial communities and metabolites were considered non-ignorable factor that affected the plant growth and development in single cultivation…”

A soil fumigant increases American ginseng ( Panax quinquefolius L.) survival and growth under continuous cropping by affecting soil microbiome assembly: a 4-year in situ field experiment

“…In our study, soil samples in all treatments were taken from one American ginseng cultivar at the same growth stage, which was the fruiting stage of ginseng grown over 4 years; thus, the effect of plant genotype and growth stage on the microbial community could be excluded. American ginseng roots and the corresponding rhizosphere soil were collected in July 2018, July 2019, July 2020, and October 2021, and the months of July to October were the peak period of ginseng root rot disease, which was reported in our previous study ( 39 ). A total of 72 soil samples were collected from the same field with varying planting years.…”