Transcriptional regulation of genes involved in sulfur assimilation in plants: Understanding from the analysis of high-affinity sulfate transporters

Sulfur is one of the essential macronutrients required for plant growth. Since the expression of several sulfur-assimilatory genes is stimulated under the condition of sulfur deficiency (-S), transcriptional regulation of these genes is considered to be critical for the control of sulfur assimilation. In the last several years, the author and coworkers have been investigated molecular mechanisms of -S-inducible expression of high-affinity sulfate transporters, SULTR1;1 and SULTR1;2 in Arabidopsis thaliana. SULTR1;1 and SULTR1;2 facilitate sulfate uptake in roots. This review summarizes the recent progress about the transcriptional regulation of these sulfate transporters by focusing on three major topics. 1) Identification of a cis-acting element involved in the -S-inducible expression of SULTR1;1. 2) Cytokinin-dependent repression of SULTR expression and sulfate uptake. 3) Central transcription regulator SLIM1 controlling -S responsive gene expression including sulfur assimilation and metabolism.