Seed mucilage plays important roles in the adaptation of desert plants to the stressful environment. Artemisia sphaerocephala is an important pioneer plant in the Central Asian cold desert, and it produces a large quantity of seed mucilage. Seed mucilage of A. sphaerocephala can be degraded by soil microbes, but it is unknown which microorganisms can degrade mucilage or how the mucilage-degrading microorganisms affect rhizosphere microbial communities or root nutrients. Here, mucilage-degrading microorganisms were isolated from the rhizosphere of A. sphaerocephala, were screened by incubation with mucilage stained with Congo red, and were identified by sequencing and phylogenetic analyses. Fungal-bacterial networks based on high-throughput sequencing of rhizosphere microbes were constructed to explore the seasonal dynamic of interactions between a mucilage-degrading microorganism and its closely related microorganisms. The structural equation model was used to analyze effects of the mucilage-degrading microorganism, rhizosphere fungal-bacterial communities, and soil physicochemical properties on root C and N. The fungus Phanerochaete chrysosporium was identified as a mucilage-degrading microorganism. Relative abundance of the mucilage-degrading fungus (MDF) was highest in May. Subnetworks showed that the abundance of fungi and bacteria closely related to the MDF also were highest in May. Interactions between the MDF and related fungi and bacteria were positive, which might enhance mucilage degradation. In addition, the MDF might regulate root C and N by affecting rhizosphere microbial community structure. Our results suggest that MDF from the rhizosphere strengthens the plant-soil-microbe continuum, thereby potentially regulating microbial interactions and root nutrients of A. sphaerocephala.

Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

种子粘液在沙漠植物适应压力环境中起着重要作用。青蒿是中亚寒漠重要的先锋植物，产生大量的种子粘液。A. sphaerocephala 的种子粘液可以被土壤微生物降解，但尚不清楚哪些微生物可以降解粘液或粘液降解微生物如何影响根际微生物群落或根部养分。在这里，从A. sphaerocephala的根际分离出粘液降解微生物，通过与刚果红染色的粘液孵育进行筛选，并通过测序和系统发育分析进行鉴定。构建了基于根际微生物高通量测序的真菌-细菌网络，以探索粘液降解微生物与其密切相关微生物之间相互作用的季节性动态。利用结构方程模型分析了粘液降解微生物、根际真菌-细菌群落和土壤理化性质对根C和N的影响。真菌Phanerochaete chrysosporium被鉴定为粘液降解微生物。5 月份粘液降解真菌 (MDF) 的相对丰度最高。子网络显示，与中密度纤维板密切相关的真菌和细菌的丰度也在 5 月份最高。MDF 与相关真菌和细菌之间的相互作用是积极的，这可能会促进粘液降解。此外，MDF 可能通过影响根际微生物群落结构来调节根 C 和 N。我们的研究结果表明，来自根际的 MDF 加强了植物-土壤-微生物的连续性，从而潜在地调节了A. sphaerocephala 的微生物相互作用和根部养分。

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