Despite the quantitative dominance of sugars within root exudates and their ecological importance in regulating plant disease development, it is not well understood how specific sugars influence the fate of fungal pathogens, the fungal community composition and, in particular, the fungal interactions in soil. In this study, a microcosm incubation experiment was conducted by adding four low-molecular-weight sugars to a Fusarium wilt pathogen-infested natural soil (i.e., Low-FO soil) and the soil further receiving Fusarium wilt pathogen inocula (i.e., High-FO soil) to understand the changes in fungal community composition and fungal interactions. Despite living in soils where multiple microbes coexist, after the addition of sugar, Fusarium wilt pathogen was selectively enriched, and sugar allowed it to sustain its dominance over time. Concurrently, the fungal richness became lower, and the fungal community composition was altered throughout 42 days of incubation. The Humicola-affiliated OTU600 showed a more rapid biomass increase than this pathogen after the addition of sugars in the Low-FO soil at some time points, and also increased over time in the High-FO soil. The community network in sugar-added soils was more complex and connected than in those without added sugar, indicating greater fungal interactions and niche-sharing. The Fusarium wilt pathogen formed positive or no connections with the keystone taxa in sugar-spiked networks in almost all cases. This suggests that the keystone taxa may have promoted or not constrained the wilt pathogen, representing a potential mechanism enabling this pathogen to vigorously proliferate after the addition of sugar.

中文翻译：

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糖改变真菌群落组成并在枯萎病病原体侵染的土壤中引起高度网络复杂性

尽管根分泌物中糖类在数量上占主导地位，并且它们在调节植物病害发展方面具有生态重要性，但目前尚不清楚特定糖类如何影响真菌病原体的命运、真菌群落组成，尤其是土壤中的真菌相互作用。在这项研究中，通过将四种低分子量糖添加到枯萎病病原体侵染的天然土壤（即低 FO 土壤）和进一步接受枯萎病病原体接种物的土壤（即高- FO 土壤）以了解真菌群落组成和真菌相互作用的变化。尽管生活在多种微生物共存的土壤中，但在添加糖后，枯萎病病原体被选择性地富集，糖使其能够随着时间的推移保持其优势地位。同时，真菌丰富度变低，真菌群落组成在 42 天的孵化过程中发生了变化。在某些时间点，在低 FO 土壤中添加糖后，腐质霉相关的 OTU600 显示出比该病原体更快的生物量增加，并且在高 FO 土壤中也随时间增加。加糖土壤中的群落网络比不加糖土壤中的群落网络更复杂、更紧密，表明真菌相互作用和生态位共享更大。枯萎病病原体几乎在所有情况下都与糖尖网络中的关键分类群形成正相关或没有关联。这表明关键类群可能促进或不抑制枯萎病菌，代表了一种潜在机制，使该病菌在添加糖后能够迅速增殖。在 42 天的孵化过程中，真菌群落组成发生了变化。在某些时间点，在低 FO 土壤中添加糖后，腐质霉相关的 OTU600 显示出比该病原体更快的生物量增加，并且在高 FO 土壤中也随时间增加。加糖土壤中的群落网络比不加糖土壤中的群落网络更复杂、更紧密，表明真菌相互作用和生态位共享更大。枯萎病病原体几乎在所有情况下都与糖尖网络中的关键分类群形成正相关或没有关联。这表明关键类群可能促进或不抑制枯萎病菌，代表了一种潜在机制，使该病菌在添加糖后能够迅速增殖。在 42 天的孵化过程中，真菌群落组成发生了变化。在某些时间点，在低 FO 土壤中添加糖后，腐质霉相关的 OTU600 显示出比该病原体更快的生物量增加，并且在高 FO 土壤中也随时间增加。加糖土壤中的群落网络比不加糖土壤中的群落网络更复杂、更紧密，表明真菌相互作用和生态位共享更大。枯萎病病原体几乎在所有情况下都与糖尖网络中的关键分类群形成正相关或没有关联。这表明关键类群可能促进或不抑制枯萎病菌，代表了一种潜在机制，使该病菌在添加糖后能够迅速增殖。