Greenhouse experiment measuring AM fungal respons to introduction of novel plants and soil biodiversity change

We conducted a greenhouse study to evaluate the impact of alien plant species on soil fungal communities at high and low soil biodiversity levels. We used two approaches to describe the novelty in the plant community: by quantifying the number of alien species present and by using Biotic Novelty Index (BNI). The latter combines species presence, co-existence time, and functional trait differences, thereby providing a standardised insight into communities with different alien plant species. Three alien plant species Galega orientalis, Saponaria ocymoides, and Solidago canadensis - that vary in their interactions with soil organisms were grown in various combinations with native plants under both regular and reduced soil biodiversity conditions. Our results indicate that only arbuscular mycorrhizal fungi, which are obligate plant symbionts, showed a significant negative response to the presence of alien plant species under high soil biodiversity. In contrast, this relationship was absent under low soil biodiversity, suggesting that reduced microbial diversity limits arbuscular mycorrhizal fungi's ability to respond to changes in plant community composition. As these fungi have relatively low abundance in fungal communities, they might be the first group to reach a critical threshold as soil biodiversity declines and therefore the dynamics of these fungi in novel communities needs special attention.We extracted DNA from soil samples using the PowerMax Soil DNA Isolation Kit (MoBio Laboratories, Inc.) and amplified the fungal ITS2 region using the degenerate primer pair fITS7:fITS7o as forward primer and ITS4 as reverse primer. The ITS2 region was sequenced on an Illumina NovaSeq platform using a 2 x 250 bp paired-end sequencing approach by Novogene Company (United Kingdom).