Hannula, E. S. | Search bioRxiv

bioRxiv2025

Pilidium lythri: A Climate-Driven Disruptor of Plant-Associated Microbiomes and Ecological Stability

While global warming accelerates phytopathogen spread, still little is known on how fungal pathogens disrupt fragile balance in plant-microbe interactions. Here, we demonstrate that the thermotolerant fungus Pilidium lythri combines broad chemical resistance with a remarkable ability to destabilize microbial communities in strawberry soil-plant systems. Using high-throughput sequencing (16S rRNA and ITS markers) across 72 samples, combined with mixed-effects modelling, source-tracking, microbiota assembly mechanisms investigation and network analysis we demonstrate that P. lythri disrupted bacterial community assembly processes, transitioning from deterministic to stochastic dynamics in the bulk soil, aligning with the Anna Karenina Principle. Despite stable dominance index (ENS) under infection bacterial and fungal communities, rhizosphere fungal diversity increased under infection. Network analysis of this niche revealed decreased fungal connectivity, with enhanced antagonistic interactions between taxa. We also noted that microbial migration patterns between niches under pathogen inoculation highlighted shifts in community interactions. Our work uncovers how emerging thermotolerant fungal phytopathogens destabilize plant holobiont without reducing diversity, important for managing emerging agricultural threats in a warming climate.

microbiology↗

bioRxiv2020

Persistence of plant-mediated microbial soil legacy effects in soil and inside roots

Plant-soil feedbacks are shaped by microbial legacies previous plants leave in the soil. We tested the persistence of such soil legacies after subsequent colonization by the same or other plant species, and whether the microbiome created by the previous plant explains current plant growth. Legacies of previous plants were detectable in soil fungal communities several months after their removal while concomitantly the effect of the current plant amplified in time. Remarkably, bacterial legacies faded away rapidly in the soil and bacterial communities were selected strongly by plant currently growing in the soil. Both fungal and bacterial legacies wrought by the previous plant were conserved inside the root endophytic compartment of the current plant and these endophytes affected significantly the plant growth. Hence, microbial soil legacies present at the time of plant establishment play a vital role in shaping plant growth even as the composition gradually changes in the soil after subsequent plant colonization, as they are taken up as endophytes in the plant. This suggests that plant-soil feedbacks may be partly mediated by a relatively stable endophytic community acquired in early ontogeny while the effects of previous plants detected on soil microbiomes vary between organisms studied. We further show that plants growing in their own soils harbor different endophytic microbiomes than plants growing in soils with legacy of other plants and that especially grasses are sensitive to species specific fungal pathogens while all plant species have less endophytic Streptomycetes when growing in their own soil. In conclusion, we show that soil legacies wrought by previous plants can remain present in the soils and inside the roots for months, even when subsequent plants colonize the soil and that these legacies also substantially modulate the plant growth.

ecology↗