Soil moisture incidentally selects for microbes that facilitate locally adaptive plant response

We examined the role of the plant vs the environment in selecting for beneficial microbes to plants in their home moisture environment, in either wet vs dry conditions. To this end, we first conditioned soil microbial communities, selecting for either dry- or wet-adapted soil microbial communities, either with or without plants. After 3 plant generations, we conducted a full reciprocal transplant of each soil community onto wet- and dry-treated plants, using the soil from the prior 3 generations as an inoculum. From plants inoculated with these ‘evolved’ soils, we measured plant biomass and height. We also measured soil nitrogen of the inoculum, and measured inoculum respiration across a water content gradient.