Mutualism mediates legume response to microbial climate legacies

Climate change is altering both soil microbial communities and the ecological context of plant-microbe interactions. Predicting how soil microbes modulate plant resilience to climate change is critical to mitigating the negative effects of climate change on ecosystems and agriculture. Previously, it was demonstrated that heat, drought, and their legacies altered soil microbiomes and potential plant symbionts. In this study, we conducted growth chamber experiments to isolate the microbially-mediated indirect effects of heat and drought on plant performance and symbiosis. In the first experiment, we found that drought and drought-treated microbes, along with their interaction, significantly decreased the biomass of Medicago lupulina plants compared to well-watered microbiomes and conditions. In a second experiment, we then tested how the addition of a well-known microbial mutualist, the rhizobium Sinorhizobium meliloti, affected climate-treated microbiomes’ impact on the M. lupulina. We f..., Study system
The temperature-free-air-controlled enhancement (T-FACE) experiment is located in an old field at Koffler Scientific Reserve (KSR, www.ksr.utoronto.ca) in Ontario, Canada (44°01'48”N, 79°32'01”W). The experimental design, treatment effectiveness, and soil microbiome analysis are fully described in Boyle et al. (2024; https://doi.org/10.1101/2023.08.04.551981), but we give a brief overview here. Plots in the T-FACE experiment grew only white spruce, Picea glauca, and were either heated, droughted, heated and droughted, or ambient (3 plots/treatment). Boyle et al. (2024) applied treatments during the growing seasons of 2020 and 2021, with rainout structures present for 8 months and heaters activated for 9 months. During active treatment, the mean soil temperature of heated plots was 3.7 ℃ or 3.6 ℃ hotter than un-heated plots in 2020 and 2021, respectively. In 2020, the mean soil volumetric water content (VWC) during droughts was 0.28 (m3/m3) in non-drought plots and 0.25 (m3/..., , # Mutualism mediates legume response to microbial climate legacies

[https://doi.org/10.5061/dryad.fj6q57449](https://doi.org/10.5061/dryad.fj6q57449)

## Description of the data and file structure

Here is data and analysis from two experiments. In the first experiment, we tested whether drought-treated soil microbes affected legumes in both dry and well-watered soil conditions in a growth chamber. We collected data on the plants in this experiment. In the second experiment, we tested whether heat- and drought-treated soil microbes affected legumes and rhizobia, under well-watered conditions only. In this second experiment, we collected data on the plants and we sequenced the root microbiome of a subset of the plants. This generated microbiome data of fungi, bacteria, and root nodule endophytes. 

### Files and variables

#### Used in Experiment 1 and 2

#### File: Climate_legacy_symbiosis.Rmd

##### **Description:**  R markdown file containing all data wrangling and analysis.

#### **...,