Genome-wide validation of the direct regulated targets for 33 nitrogen-early response transcription factors

The direct targets of 33 Nitrogen-early responsive TFs were identified using the TARGET system. Arabidopsis plants were grown on low nitrogen (1mM KNO3) and after 10 days protoplasts were generated from root tissue, Cells were transfected with a vector containing the GR-TF fusion and incubated overnight. Each experiment also included a GR-only empty vector control. In the morning, samples were pre-treated with 20 mM KNO3 and 20 mM NH4NO3 for 2 hours, and cycloheximide for 20 minutes, before TF entry into the nucleus was induced with dexamethasone. 3 hours after dex treatment samples were FACS sorted into RNA extraction buffer and RNA-seq libraries were generated. Transcriptional response to each TF compared to empty vector was assayed. Overall design: Genome-wide direct regulated targets of 33 TFs were determined by comparison to an empty vector control. Vectors were expressed in protoplasts isolated from root tissue, samples were done in triplicate, and sequenced using the Illumina NextSeq platform.