DOI: 10.5285/e09db3ad-c54a-4f99-bf3c-37ee63fc2998
title: Responses of drought-adapted plants and soil microbial communities to drought conditions in plant-soil microcosms

description: This dataset contains information on the performance of soil microbial communities (from field soil washes), soil synthetic microbial populations (from isolates within a single bacterial genus) and plants each originating from either drought and control long-term climate treatments at the Buxton Climate Change Impacts Lab (BCCIL), in a microcosm experiment. Plant and microbe provenance were manipulated to effect different combinations of climate ancestry in different microcosm pots. In addition, a factorial watering treatment (control or drought treatment) was applied. Isolates of Pseudomonas used to found experimental populations of soil microbes had been sampled from the roots of Festuca ovina in the control and drought treatments at BCCIL. 

Variables measured included soil respiration, plant traits, plant available soil nutrients, soil enzyme activities, soil respiration responses to substrate addition (in a substrate utilisation profiling assay), and soil respiration responses to drought (in a substrate utilisation profiling assay). 
description: Bacterial isolates from BCCIL (44 from genus Pseudomonas) were raised in liquid media and used to create artificial populations of isolates representing the drought treatment at BCCIL (22 isolates equally represented by titre) and the control treatment at BCCIL (22 isolates equally represented). In addition, soil wash inoculum representing the entire soil microbial community at Buxton was prepared either from fresh drought treatment or control treatment soil from BCCIL. These synthetic bacterial populations and climate adapted microbial communities were used to inoculate sterilised soil-plant microcosms in pots (~1000 ml soil volume). Soil was autoclaved before inclusion in the pots while plants (Festuca ovina with ancestry in different treatments at BCCIL) were surface sterilised using a bleach solution. 

The F. ovina plants used in the experiment had two parents who were either both sampled from the drought treatment at Buxton (11 clonal lines, representing plant drought adaptation) or both sampled from the control treatment at Buxton (11 clonal lines, representing plant control treatment adaptation). Each of the populations of plants representing the two climate ancestries were exposed to a total of eight treatments. 

First, the type of inoculation (either artificial Pseudomonas population or field soil-wash community) was varied (two levels). Second the origin of the soil microbes was varied (drought or control; two levels). Finally a watering treatment was imposed (control or drought; two levels). These treatments were combined factorially for a total of eight treatment combinations. Experimental replicates were assigned randomly to tables (blocks) in a polytunnel. 

Microcosms in the control watering treatment were topped up to field capacity, whereas those in the drought treatment were not watered (with a target volumetric soil content of 5%). Substrate utilisation profiling was carried out by taking soil samples from the microcosms at the end of the experiment, which were amended with different substrates (water, glucose, cellulose, artificial root exudate) or experimentally dried in the lab prior to evaluation of respiration in MicroResp(TM) colourimetric microplates using a FLUOstar Omega spectrophotometer (BMG Labtech, Ortenberg, Germany) before to detect CO2 efflux. 

Soil respiration was measured with a Li Cor Li 8100 IRGA and Li Cor 8150 Multiplexer. Soil enzyme activity was measured via the addition of fluorescently labelled substrates to soil enzyme extractions with detection of fluorescence on a FLUOstar Omega spectrophotometer. Plant available nutrients were assessed using Plant Root Simulator probes (Western Ag).