Salinization is considered a significant threat to soil ecosystem and plant growth in arid and semiarid regions. Soil microorganisms are supposed to be essential in relieving soil salinization and enhancing plant salt tolerance. However, although the responses of soil fungal diversity and community structure to salt stress have been investigated, major knowledge gaps remain in the interactions and community assembly of abundant and rare fungal taxa, and fungal functional characteristics under different salt intensities. Here, next-generation sequencing technology were used to investigate the response of all, abundant and rare fungal taxa to salt stress in arid and semiarid regions. The results demonstrated that high salt stress reduced the complexity and stability of fungal networks and increased fungal collaborations. Rare taxa held a key position in the co-occurrence network and exhibited greater proficiency in collaborating with intermediate and rare taxa, thereby augmenting the resistance of the community and maintaining its stability. Notably, with increasing salt stress, the importance of rare taxa gradually enhanced, while the importance of abundant taxa decreased. Moreover, fungal communities were manipulated by stochastic processes under salt stress, while were also influenced by deterministic processes (heterogeneous selection), especially for rare taxa. Furthermore, low salinity conditions promoted the colonization of saprophytic and symbiotic fungi and inhibited the growth of pathogenic fungi. Functional groups associated with fungal parasite-soil saprotroph-undefined saprotroph function were extremely sensitive to soil salinity and exerted a pivotal influence in sustaining community stability. Our findings may broaden our understanding of how abundant and rare fungi react to salt stress, making it easier to forecast the possible loss of biodiversity due to soil salinization, and offering microbial references for the development of saline-alkaline soil.

中文翻译：

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干旱和半干旱地区盐度梯度下土壤真菌群落差异

盐碱化被认为对干旱和半干旱地区的土壤生态系统和植物生长构成重大威胁。土壤微生物被认为对于缓解土壤盐碱化和增强植物耐盐性至关重要。然而，尽管已经研究了土壤真菌多样性和群落结构对盐胁迫的响应，但在丰富和稀有真菌类群的相互作用和群落组装以及不同盐强度下真菌的功能特征方面仍然存在主要知识空白。在这里，新一代测序技术被用来研究干旱和半干旱地区所有丰富和稀有的真菌类群对盐胁迫的响应。结果表明，高盐胁迫降低了真菌网络的复杂性和稳定性，并增加了真菌协作。稀有类群在共现网络中占据着关键地位，并在与中间和稀有类群的协作方面表现出更高的熟练程度，从而增强了群落的抵抗力并保持了其稳定性。值得注意的是，随着盐胁迫的加剧，稀有类群的重要性逐渐增强，而丰富类群的重要性逐渐下降。此外，真菌群落在盐胁迫下受到随机过程的操纵，同时也受到确定性过程（异质选择）的影响，特别是对于稀有类群。此外，低盐条件促进了腐生和共生真菌的定殖，抑制了病原真菌的生长。与真菌寄生虫-土壤腐生菌-未定义的腐生菌功能相关的功能群对土壤盐分极其敏感，并对维持群落稳定性发挥关键影响。我们的研究结果可能会拓宽我们对丰富和稀有真菌如何应对盐胁迫的理解，从而更容易预测土壤盐碱化可能导致的生物多样性丧失，并为盐碱土壤的发展提供微生物参考。