Density and root exudates mediate Arabidopsis response to copper

Premise of the study: Plants grown at high densities show increased tolerance to heavy metals for reasons that are not clear. A potential explanation is the release of citrate by plant roots, which binds metals and prevents uptake. Thus, pooled exudates at high plant densities could increase tolerance. We tested this exclusion facilitation hypothesis using mutants of Arabidopsis thaliana defective in citrate exudation.
Methods: Wild type Arabidopsis and two allelic mutants for the Ferric Reductase Defective 3 (FRD3) gene were grown at four densities and watered with copper sulfate at four concentrations. Plants were harvested before bolting and dried. Shoot biomass was measured, and shoot material and soil were digested in nitric acid. Copper contents were determined by atomic absorption.
Key results: In the highest copper treatment, density-dependent reduction in toxicity was observed in the wild type but not in FRD3 mutants. For both mutants, copper concentrations per gram biomass wer..., Biomass is for dry weight at harvest; copper concentrations were determined by atomic absorption following acid digestion of shoots., , # Data from: Density and root exudates mediate Arabidopsis response to copper

Data provides the biomass of individual Arabidopsis thaliana plants from three varieties grown at four densities in the presence of various concentrations of copper in soil.

##### Description of the data and file structure

Column A is the label of plant genotype: A = wild-type; B = frd3-3 mutant; C = frd3-1 mutant

Column B is pot number

Column C is replicate (1-4)

Column D is density (no. of plants per pot = 1, 3, 5 or 7)

Column E is the copper treatment level (micrograms per g in potting mix)

Columns F-L are the dry mass of individual plants

Column M is total micrograms of copper found after digestion of plant material (recovered from shoot mass)

\".\" indicates values that were not collected. For example, at a plant density of 1, dry mass values for plants 2-7 will be absent (\".\").