Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871, Frederiksberg, Denmark.
Department of Biology, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen, Denmark.
FEMS Microbiol Ecol. 2019 Mar 1;95(3). doi: 10.1093/femsec/fiz020.
Most plants form symbiotic associations with arbuscular mycorrhizal fungi (AMF). AMF increase the uptake of plant nutrients by extending their extra-radical mycelium (ERM) in the soil where other groups of microorganisms may suppress the activity of the ERM. However, little is known about such suppression in natural soils. This work aimed to investigate the incidence of AMF suppression among soils sampled from highly variable natural ecosystems, and used 33P uptake by the ERM to evaluate AMF activity. A second aim was to identify factors behind the observed AMF-suppression. We found that AMF-suppressiveness varied markedly among natural soils and occurred more frequently in low pH than in high pH soils. A previous study for cultivated soils revealed a strong biological component of suppressiveness against AMF, and in accordance we found that the composition of both fungal and bacterial communities differed significantly between AMF-suppressive and non-suppressive natural soils. Acidobacteria, Acidothermus, Xanthomonadaceae, Archaeorhizomyces sp., Mortierella humilis and some Mycena spp. were significantly more abundant in AMF-suppressive soils and may therefore be direct antagonists of AMF. This implies that the functioning of AMF in natural ecosystems is strongly modulated by specific soil microbes.
大多数植物与丛枝菌根真菌（AMF）形成共生关系。AMF 通过延伸其在土壤中的外生菌根（ERM）来增加植物养分的吸收，而其他微生物群可能会抑制 ERM 的活性。然而，对于自然土壤中的这种抑制作用，我们知之甚少。本研究旨在调查从高度可变的自然生态系统中采集的土壤中 AMF 抑制的发生率，并使用 ERM 对 33P 的吸收来评估 AMF 活性。第二个目的是确定观察到的 AMF 抑制背后的因素。我们发现，AMF 在自然土壤中的抑制性差异很大，在 pH 值较低的土壤中比在 pH 值较高的土壤中更为常见。之前对耕作土壤的研究揭示了 AMF 抑制的强烈生物成分，根据这一研究，AMF 抑制性和非抑制性自然土壤中的真菌和细菌群落组成存在显著差异。酸杆菌、酸热菌、黄单胞科、Archaeorhizomyces sp.、Mortierella humilis 和一些 Mycena spp. 在 AMF 抑制性土壤中更为丰富，因此可能是 AMF 的直接拮抗物。这意味着 AMF 在自然生态系统中的功能受到特定土壤微生物的强烈调节。
