Suppression of the activity of arbuscular mycorrhizal fungi by the soil microbiota

Abstract

Arbuscular mycorrhizal fungi (AMF) colonise roots of most plants; their extra-radical mycelium (ERM) extends into the soil and acquires nutrients for the plant. The ERM coexists with soil microbial communities and it is unresolved whether these communities stimulate or suppress the ERM activity. This work studied the prevalence of suppressed ERM activity and identified main components behind the suppression. ERM activity was determined by quantifying ERM-mediated P uptake from radioisotope-labelled unsterile soil into plants, and compared to soil physicochemical characteristics and soil microbiome composition. ERM activity varied considerably and was greatly suppressed in 4 of 21 soils. Suppression was mitigated by soil pasteurisation and had a dominating biotic component. AMF-suppressive soils had high abundances of Acidobacteria, and other bacterial taxa being putative fungal antagonists. Suppression was also associated with low soil pH, but this effect was likely indirect, as the relative abundance of, e.g., Acidobacteria decreased after liming. Suppression could not be transferred by adding small amounts of suppressive soil to conducive soil, and thus appeared to involve the common action of several taxa. The presence of AMF antagonists resembles the phenomenon of disease-suppressive soils and implies that ecosystem services of AMF will depend strongly on the specific soil microbiome.

Arbuscular mycorrhizal fungi stimulate organic phosphate mobilization associated with changing bacterial community structure under field conditions

“…The membranes with the above size of pores are usually used to study nutrient (e.g., N and P) mobilization and utilization by the interaction between AMF and soil bacteria (Hodge et al, 2001;Leigh et al, 2011;Nuccio et al, 2013;Zhang et al, 2016;Storer et al, 2017). The effects of the different pores on P diffusion can be neglected in this system and has been demonstrated to be negligible (Li et al, 1991;Zhang et al, 2016;Svenningsen et al, 2018). Using this method, we demonstrate, for the first time, AMF and their associated microbiome could enhance organic P mineralization under field conditions and go on to discuss the potential mechanism.…”

Arbuscular Mycorrhizal Fungal Assemblages Significantly Shifted upon Bacterial Inoculation in Non-Contaminated and Petroleum-Contaminated Environments

“…The bacterial inoculation in this experiment was associated with significantly increased root colonization percentages, but only in the contaminated substrate. AMF activity through its extra radical mycelium has been found to be influenced by soil microbiota assemblages [75]. The stress-inducing toxicity of PH contaminants could explain why significant changes in root colonization were only observed in the contaminated substrate, as it might have led to more dynamic and responsive root/AMF interactions.…”

How do arbuscular mycorrhizal fungi handle phosphate? New insight into fine‐tuning of phosphate metabolism

“…() demonstrated that, even in the presence of native microbial community, inoculation with a PSB stimulated AM fungal growth, resulting in the enhancement of host Pi acquisition. Given that in natural soil not only beneficial bacteria but also antagonists/competitors that suppress extraradical hyphal growth of AM fungi exist (Svenningsen et al ., ), further studies are needed to identify environmental factors that drive microbial community to enhance mycorrhizal functioning.…”