Data_Sheet_1_Generalist Taxa Shape Fungal Community Structure in Cropping Ecosystems.docx

Fungi regulate nutrient cycling, decomposition, symbiosis, and pathogenicity in cropland soils. However, the relative importance of generalist and specialist taxa in structuring soil fungal community remains largely unresolved. We hypothesized that generalist fungi, which are adaptable to various environmental conditions, could potentially dominate the community and become the basis for fungal coexisting networks in cropping systems. In this study, we identified the generalist and habitat specialist fungi in cropland soils across a 2,200 kms environmental gradient, including three bioclimatic regions (subtropical, warm temperate, and temperate). A few fungal taxa in our database were classified as generalist taxa (~1%). These generalists accounted for >35% of the relative abundance of all fungal populations, and most of them are Ascomycota and potentially pathotrophic. Compared to the specialist taxa (5–17% of all phylotypes in three regions), generalists had a higher degree of connectivity and were often identified as hub within the network. Structural equation modeling provided further evidence that after accounting for spatial and climatic/edaphic factors, generalists had larger contributions to the fungal coexistence pattern than habitat specialists. Taken together, our study provided evidence that generalist taxa are crucial components for fungal community structure. The knowledge of generalists can provide important implication for understanding the ecological preference of fungal groups in cropland systems.

真菌可调控农田土壤中的养分循环、有机质分解、共生作用与致病过程。然而，泛化类群（generalist taxa）与特化类群（specialist taxa）在塑造土壤真菌群落结构中的相对重要性，目前仍未得到充分阐明。本研究提出假说：能够适应多种环境条件的泛化真菌类群，有望在农田生态系统的真菌群落中占据主导地位，并成为真菌共存网络的核心基础。本研究针对跨越2200公里的环境梯度下的农田土壤展开分析，涵盖亚热带、暖温带与温带3个生物气候区，从中鉴定出泛化真菌与生境特化真菌类群。本研究数据库中仅有约1%的真菌类群被归类为泛化类群，但这些泛化类群的相对丰度占所有真菌种群的35%以上，且其中绝大多数隶属于子囊菌门（Ascomycota），多为潜在寄生营养型类群。与特化类群（3个生物气候区中占所有系统发育型的5%~17%）相比，泛化类群具有更高的连接度，且常被鉴定为真菌共存网络中的枢纽节点。结构方程模型（structural equation modeling）进一步证实：在控制空间、气候与土壤因子的影响后，泛化类群对真菌共存模式的贡献度显著高于生境特化类群。综上，本研究证实泛化类群是农田土壤真菌群落结构的关键组成部分；对泛化类群的认知，可为理解农田系统中真菌类群的生态偏好提供重要参考。