Soil microbial species loss affects plant biomass and survival of an introduced bacterial strain, but not inducible plant defences

- Background and Aims: Plant growth-promoting rhizobacteria (PGPR) strains can influence plant-insect interactions. However, little is known about the effect of changes in the soil bacterial community in general and especially the loss of rare soil microbes on these interactions. Here, the influence of rare soil microbe-reduction on induced systemic resistance (ISR) in a wild ecotype of Arabidopsis thaliana against the aphid Myzus persicae was investigated.
- Methods: To create a gradient of microbial abundances, soil was inoculated with a serial dilution of a microbial community and responses of Arabidopsis plants that originated from the same site as the soil microbes were tested. Plant biomass, transcription of genes involved in plant defences, and insect performance were measured. In addition, the effects of the PGPR strain Pseudomonas fluorescens SS101 on plant and insect performance were tested under influence of the various soil dilution treatments.
- Key Results: Plant biomas...