Nitrogen and phosphorus fertilization consistently favor pathogenic over mutualistic fungi in grassland soils

Abstract

Ecosystems across the globe receive elevated inputs of nutrients, but the consequences of this for soil fungal guilds that mediate key ecosystem functions remain unclear. We find that nitrogen and phosphorus addition to 25 grasslands distributed across four continents promotes the relative abundance of fungal pathogens, suppresses mutualists, but does not affect saprotrophs. Structural equation models suggest that responses are often indirect and primarily mediated by nutrient-induced shifts in plant communities. Nutrient addition also reduces co-occurrences within and among fungal guilds, which could have important consequences for belowground interactions. Focusing only on plots that received no nutrient addition, soil properties influence pathogen abundance globally, whereas plant community characteristics influence mutualists, and climate influence saprotrophs. We show consistent, guild-level responses that enhance our ability to predict shifts in soil function related to anthropogenic eutrophication, which can have longer-term consequences for plant communities.

Transcriptomic and Metabolomic Approaches Deepen Our Knowledge of Plant–Endophyte Interactions

“…Along the continuum, if the symbiont can obtain benefits from the host at no cost in the absence of any enemies, then this microbe is on course toward a parasitic lifestyle (Vorburger and Gouskov, 2011). Notably, the degree of damage incurred by the host and the extent of resource acquisition could be intensified depending on a nutritious environment for pathogens and driven by a great selection pressure to propagate given the limited life span of the microbe (Rafaluk-Mohr, 2019;Lekberg et al, 2021). Once the microbe overcomes all the defense barriers in its host plant, thus, putting the host into disease state, it is usually called a pathogen.…”

Rhizosphere microbiome: Functional compensatory assembly for plant fitness

“…Physico-chemical properties, such as soil pH, nutrient availability, soil moisture and temperature, among different soil types or along biogeographical distance patterns shape the structure of the soil microbial community [21] , [22] , [23] , [24] , which determines the initiation of rhizosphere community assembly. In particular, anthropogenic activities, generally agricultural management practices, have profound impacts on the physico-chemical properties of the soil, consequently influencing the soil and the rhizosphere microbial community [25] , [26] . Amplicon sequencing-based studies focusing on the rhizosphere microbial communities of different A. thaliana populations have demonstrated that soil type is the primary driving factor affecting the rhizosphere bacterial community [15] ; however, climate is more important for the rhizosphere fungal community than soil type [27] .…”

Nutrient enrichment increases invertebrate herbivory and pathogen damage in grasslands

“…or particular functional groups, such as grasses (De Schrijver et al, 2011). Eutrophication can also shift growth relative to defence in individual plants (Stamp, 2003) or increase soil pathogens relative to mutualists (Lekberg et al, 2021).…”