ABSTRACT

Arbuscular mycorrhizal fungi (AMF) community assembly has been investigated at regional and local scales, but was largely unknown at micro-scale. The AMF community at soil aggregate level was studied to promote the understanding of their distribution at micro-scale. Surface soil associated with Eremochloa ophiuroides, Imperata cylindrica and Paspalum notatum were sieved into three fractions: large macroaggregates (LMA, >2mm), small macroaggregates (SMA, 0.25–2mm) and microaggregates (MA, <0.25mm). Illumina MiSeq sequencing revealed that AMF communities were dominated by Glomus (>90%) and Paraglomus (>6%), across plants. Higher AMF diversity was found in SMA or MA than LMA, which was positively related to soil nutrient levels. The soil pH and available phosphorus were related to the AMF diversity in SMA, while available potassium (AK) was related to the AMF diversity in MA. The correlation between Glomus, Claroideoglomus, or Paraglomus and soil pH or available phosphorus in SMA, and between Glomus and AK in MA could explain AMF diversity changes. The AMF community composition was consistent in three soil aggregate fractions. Our results demonstrate that AMF diversity, but not community composition, differ across soil aggregate sizes. The AMF diversity changes are related to edaphic factors, following a microscale-dependent pattern.

摘要

丛枝菌根真菌 (AMF) 群落组装已经在区域和地方尺度上进行了研究，但在微观尺度上很大程度上是未知的。研究了土壤团聚体水平的 AMF 群落，以促进对其在微观尺度上分布的理解。与 Eremochloa ophiuroides、Imperata cylindrica 和 Paspalum notatum相关的地表土壤 被筛分为三个部分：大的大聚集体（LMA，>2mm）、小的大聚集体（SMA，0.25-2mm）和微聚集体（MA，<0.25mm）。Illumina MiSeq 测序显示 AMF 群落以 Glomus  (>90%) 和 Paraglomus为主 (>6%)，跨植物。SMA或MA的AMF多样性高于LMA，这与土壤养分水平呈正相关。土壤 pH 值和速效磷与 SMA 的 AMF 多样性有关，而速效钾 (AK) 与 MA 的 AMF 多样性有关。SMA 中Glomus、Clroideoglomus或 Paraglomus 与土壤 pH 或有效磷 之间的相关性，以及 Glomus之间的相关性 MA 中的 AK 可以解释 AMF 多样性的变化。AMF 群落组成在三个土壤团聚体组分中是一致的。我们的研究结果表明，AMF 多样性，而不是群落组成，在土壤团聚体大小方面存在差异。AMF 多样性变化与土壤因素有关，遵循微尺度依赖模式。