云南文山健康三七种植年限对根际微生物群落的影响

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

摘要:

【背景】三七的连作障碍与微生物区系失衡有一定关联，了解种植年限对三七微生物区系的影响，判断根际微生物区系是否失衡，对三七连作障碍的防治具有重要意义。【目的】探究文山不同种植年限健康三七根际土壤细菌和真菌群落结构、多样性差异，以及与种植年限之间的关联，为后续缓解三七连作障碍提供理论依据。【方法】采集一年生、二年生和三年生健康三七根际土壤，采用16S rRNA基因和ITS序列进行高通量测序。对测序结果进行分析，比较一年生、二年生和三年生健康三七根际土壤细菌和真菌的多样性和群落分布规律及与种植年限的关联。【结果】一年生健康三七根际细菌和真菌群落的α指数均显著高于二年生和三年生。通过β多样性分析发现，一年生健康三七根际土壤中真菌群落结构与其他年限的真菌群落结构有较大差异。相关性分析结果表明，真菌的均匀度和香农指数与种植年限呈现显著的负相关性，其余指数不显著相关。三七根际丰富度前三的门和属，除Acidobacteria和Aquicella丰富度随着三七种植年限的增加而显著增加外，其余群落丰度都与种植年限呈负相关。细菌中Bacteroidetes、Proteobacteria和真菌中Ascomycota、Basidiomycota、Chytridiomycota的丰富度随着种植年限增加而降低。在属水平上，细菌中Opitutus和真菌中Mortierella、Clitopilus、Pholiota的丰富度随着三七种植年限的增加而降低。在二年生三七根际土壤中病原真菌Alternaria、Cylindrocarpon、Fusarium和Pestalotiopsis的丰富度低于一年生和三年生，而有益真菌Mucor和Bacillus的丰富度却呈相反趋势。同时，有益细菌Flavobacterium和有益真菌Myxocephala、Aspergillus的丰富度随着种植年限的增加呈下降趋势。【结论】三七种植年限的增加，会引起三七根际微生物区系失衡，增加根际病原真菌属的丰度，同时降低一些有益真菌属的丰度。

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.