Understanding the contribution of soil microbial communities to plant stress tolerance is a key challenge. Serpentine soils and plant adaptation to their particular stresses has been developed into a model system for plant-soil interactions, but the role of microbial communities in serpentine tolerance is poorly understood. Here, I tested the hypothesis that serpentine-indifferent plants benefit from associations with serpentine microorganisms when growing on serpentine soil. In a greenhouse experiment, three serpentine-indifferent plants were grown on serpentine soils and slurries were used to reconstitute microbial communities from serpentine or nonserpentine soils. Live serpentine soil was used as a control. Autoclaved soil removed serpentine microorganisms from the ecosystem. After 11 weeks, plant survival, leaf number, root length, shoot height, plant height, root-to-shoot ratio, and water content was recorded for each sample. 16S sequencing and DADA2 analysis was used to examine microbial communities communities from greenhouse-grown plants and compared to that of field-grown plants.
Results/Conclusions
Plant survival and growth parameters were largely unaffected by serpentine microbial treatments, but plant roots were longer in serpentine compared to reintroduced microbial communities. Additionally, soil microbial communities differed among microbial inoculation treatments (P<0.001). Sequence variants from genera within the Firmicutes, Actinobacteria, Bacteroidetes, and Proteobacteria were found to differ between soil treatments. Specifically, Sphingomonas, Piscinibacter, Pedobacter, and Blastococcus were abundant in live serpentine soil, while Paenibacillus and Lysinibacillus were deficient in live serpentine soil compared to other treatments. Microbial communities from greenhouse-grown plants differed significantly from the same plant species sampled in the field. These results suggest that although soil bacterial communities differ between serpentine and non-serpentine soils, their functional consequences for plant growth and performance were minimal under the experimental growth conditions. Further experimental and functional studies are suggested to understand the functional role of serpentine microbial communities.