Negative Plant-Soil Feedback Driven by Re-assemblage of the Rhizosphere Microbiome With the Growth of Panax notoginseng

Abstract

There is a concerted understanding of the accumulation of soil pathogens as the major driving factor of negative plant-soil feedback (NPSF). However, our knowledge of the connection between plant growth, pathogen build-up and soil microbiome assemblage is limited. In this study, significant negative feedback between the soil and sanqi ( Panax notoginseng ) was found, which were caused by the build-up of the soil-borne pathogens Fusarium oxysporum , F. solani , and Monographella cucumerina . Soil microbiome analysis revealed that the rhizospheric fungal and bacterial communities were changed with the growth of sanqi. Deep analysis of the phylum and genus levels corroborated that rhizospheric fungal Ascomycota, including the soil-borne pathogens F. oxysporum , F. solani , and especially M. cucumerina , were significantly enriched with the growth of sanqi. However, the bacteria Firmicutes and Acidobacteria, including the genera Pseudomonas , Bacillus, Acinetobacter and Burkholderia , were significantly suppressed with the growth of sanqi. Using microbial isolation and in vitro dual culture tests, we found that most isolates derived from the suppressed bacterial genera showed strong antagonistic ability against the growth of sanqi soil-borne pathogens. Interestingly, inoculation of these suppressed isolates in consecutively cultivated soil could significantly alleviate NPSF. In summary, sanqi growth can suppress antagonistic bacteria through re-assemblage of the rhizosphere microbiome and cause the accumulation of soil-borne pathogens, eventually building negative feedback loops between the soil and plants.

Linking Short-Chain N-Acyl Homoserine Lactone-Mediated Quorum Sensing and Replant Disease: A Case Study of Rehmannia glutinosa

“…Similar findings were reported in our previous study on the rhizosphere microbiome of R. glutinosa based on barcoded pyrosequencing (Wu et al, 2018b). Luo et al (2019) indicated that P. notoginseng planting resulted in negative plant-soil feedback due to a decline in the beneficial rhizobacteria including the genera Pseudomonas and Bacillus in the rhizosphere. Pseudomonas spp.…”

“…However, large-scale crop monoculture results in many problems including a loss of crop genetic diversity, an increase in disease incidence, a decline in crop quality and even the fragility of ecosystem functioning (Jacques and Jacques, 2012;Mariotte et al, 2018;. Consecutive monoculture problems, also known as replant problems or replant disease, are especially severe in the cultivation of medicinal herbs, such as Rehmannia glutinosa, Panax notoginseng, Pseudostellaria heterophylla, and Panax ginseng (Dong et al, 2018a;Luo et al, 2019;Wu et al, 2019;Zhang et al, 2019). It was reported that approximately 70% of medicinal herbs using tuberous roots were attacked by replant disease (Wu et al, 2016c).…”

Probiotic Consortia: Reshaping the Rhizospheric Microbiome and Its Role in Suppressing Root-Rot Disease of Panax notoginseng

“…Inoculation of probiotic consortia may indirectly promote the growth of other beneficial bacteria and fungi, thereby suppressing root-rot. We found after sequencing that the abundance of Trichoderma in treatments A, B, C, and D gave better results as compared with control BT group; Trichoderma has been reported to be a biocontrol fungus having a wide range of antagonistic properties, and it can effectively inhibit the growth of F. oxysporum and Fusarium solani (Luo et al, 2019;Sallam et al, 2019). There was a negative relationship between the probiotic consortia abundance and Fusarium abundance, and inoculated probiotic consortia constrained Fusarium pathogen density.…”

Ginsenosides in root exudates of Panax notoginseng drive the change of soil microbiota through carbon source different utilization

“…Individual colonies were picked out after incubating at 25°C for 4-5 days, and inoculated on NA media (bacteria) or PDA (fungi) to obtain pure cultures. The fungi were identified by a morphological method and ITS amplification (Luo et al 2019). The bacteria were identified through 16S rRNA amplification (Luo et al 2019).…”

“…Ginsenosides were also demonstrated to inhibit the growth of Trichoderma hamatum but stimulate the growth of root rot pathogens (Nicol et al 2003;Yang et al 2015Yang et al , 2018b. Previous studies have found that the growth of P. notoginseng, P. ginseng, and P. quinquefolium could reassemble the rhizosphere microbiota and inferred that root exudates might be a key driving factor (Li et al 2012;Luo et al 2019;Jiang et al 2019). However, little is known about the effects of root exudates and ginsenosides in root exudates on the soil microbiota.…”