New publication from Maciá-Vicente et al. in Molecular Ecology: The structure of root-associated fungal communities is related to the long-term effects of plant diversity on productivity

Root-associated fungi could play a role in determining both the positive relationship between plant diversity and productivity in experimental grasslands, and its strengthening over time. This hypothesis assumes that specialized pathogenic and mutualistic fungal communities gradually assemble over time, enhancing plant growth more in species-rich than in species-poor plots. To test this hypothesis, we used high-throughput amplicon sequencing to characterize root-associated fungal communities in experimental grasslands of 1 and 15 years of age with varying levels of plant species richness. Specifically, we tested whether the relationship between fungal communities and plant richness and productivity becomes stronger with the age of the experimental plots. Our results showed that fungal diversity increased with plant diversity, but this relationship weakened rather than strengthened over the two time points. Contrastingly, fungal community composition showed increasing associations with plant diversity over time, suggesting a gradual build-up of specific fungal assemblages. Analyses of different fungal guilds showed that these changes were particularly marked in pathogenic fungi, whose shifts in relative abundance are consistent with the pathogen dilution hypothesis in diverse plant communities. Our results suggest that root-associated fungal pathogens play more specific roles in determining the diversity–productivity relationship than other root-associated plant symbionts.

Details are in the caption following the image — Relationships between plant richness and measures of soil microbial biomass (a) and fungal diversity (b), and of primary plant production and fungal diversity (c, d). Shading in point colours indicates measures taken in young or old experimental plant communities (see key). Response variables (y-axes) are represented by partial residuals, after the effects of covariates were accounted for in multiple linear mixed-effects regression analyses (see Table 1 for the effects of individual predictors). Regression lines between response and predictor variables are only shown for significant relationships (p ≤ .05). Fungal diversity was calculated according to the Shannon diversity index and is represented as numbers of effective ASVs (ES). The variables plant richness, aboveground biomass and root biomass were square-root or log-transformed, as indicated in the respective axis labels, to comply with the assumption of residual distribution in linear mixed-effects models.

Reference:

Maciá-Vicente, J. G., Francioli, D., Weigelt, A., Albracht, C., Barry, K. E., Buscot, F., Ebeling, A., Eisenhauer, N., Hennecke, J., Heintz-Buschart, A., van Ruijven, J., & Mommer, L. (2023). The structure of root-associated fungal communities is related to the long-term effects of plant diversity on productivity. Molecular Ecology, 00, 1– 15. https://doi.org/10.1111/mec.16956