Measurement of Uptake and Root-to-Shoot Distribution of Sulfate in Arabidopsis Seedlings

[Abstract] Sulfur is an essential macronutrient required for growth and development of plants. Plants take up sulfate from the soil environment through the function of plasma membrane-bound sulfate transporters expressed at the root surface cell layers. Plants then utilize the incorporated sulfate as the main sulfur source to synthesize sulfur-containing compounds such as cysteine and methionine. Measurement of root sulfate uptake capacity is essential for analyzing mutants showing altered levels of sulfate transporters and/or sulfur metabolic enzymes as a result of genetic modification or due to the effect of intrinsic or environmental factors modulating their gene expression. The method described in this protocol allows quantitative investigation of sulfate uptake rates and root-to-shoot sulfate distribution in Arabidopsis seedlings using [35S] sulfate as a radioactive tracer. The method is designed for parallel comparisons of multiple Arabidopsis accessions, mutants or transgenic lines at the seedling stage.