Effects of different planting years of healthy Panax notoginseng on the rhizosphere microbial community in Wenshan of Yunnan province

Abstract:

[Background] The severe continuous cropping obstacles of Panax notoginseng may be related to the microbial community imbalance. Hence, it is important to know whether the microflora could be imbalanced with the change of planting years of Panax notoginseng during the planting process. [Objective] Structure and diversity differences of bacterial and fungal communities in rhizosphere soils of healthy Panax notoginseng with different planting years were studied. Our research can also provide theoretical basis for further reducing Panax notoginseng monocropping obstacle. [Methods] The samples were collected from Panax notoginseng healthy rhizosphere soil planting for one-, two- and three-year in Yanshan county of Wenshan. High-throughput sequencing of 16S rRNA gene and ITS genes were used to compare the diversity and community distribution of bacterial and fungal in rhizosphere soils of healthy Panax notoginseng planting for one-, two- and three-year. [Results] The alpha indices of the one-year healthy rhizosphere bacterial and fungal rhizosphere communities were obviously higher than those of the two- and three-year samples. The results of beta diversity revealed that the bacterial community structures in the one-year Panax notoginseng rhizosphere were different with other treatments. The results of correlation analysis showed that the equitability and shannon indices of fungi showed significant negative correlations with planting years, while the other indices were not significantly correlated. The abundances of Acidobacteria and Aquicella increased with the plantation year, while other top three phylum and genus were all negatively related to the planting years. Among them, the abundance of Bacteroidetes, Proteobacteria, Ascomycota, Basidiomycota and Chytridiomycota phylum decreased with planting years increasing. At the genus level, the abundances of Opitutus of bacteria, Mortierella, Clitopilus and Pholiota of fungi decreased with planting years increasing. The abundances of Alternaria, Cylindrocarpon, Fusarium and Pestalotiopsi genus of two-year rhizosphere soil would be lower than that of one- and three-year treatments, while the abundances of Mucor and Bacillus would show opposite trend. Meanwhile, the richness of the beneficial bacteria like Flavobacterium, beneficial fungi like Myxocephala and Aspergillus decreased with planting years increasing. [Conclusion] With the increase of Panax notoginseng planting years, the microbial community of Panax notoginseng rhizosphere was imbalanced. The abundances of pathogenic fungal genus were enhanced with planting years increasing, while the abundances of beneficial fungal genus were decreased.