Graduate Research Assistant University of Georgia Athens, Georgia
Body of Abstract: Transcription factors (TFs) play an important role in many plant pathways. In Maize, there are over 3000 TFs and we don’t know the target pathways of many of these. Our goal is to test TF function large-scale through ectopic expression. Ectopic expression of TFs induces the native pathways and with that information we can begin to tease apart the native function of those TFs. We have established methods for high-throughput transformation of leaf protoplasts in 384-well plates using polyethylene glycol (PEG). Median transformation efficiencies are >70% and consistent between days and across the plates. We have used this to express 164 individual TFs in duplicate and measure the full transcriptome-wide response by RNA sequencing. Replicate samples consistently show a higher Pearson’s correlation than random sample pairs. 30% of TFs cluster immediately next to their replicate indicating that many TFs induce reproducible responses and the responses are sufficiently distinct to drive clustering. We also find evidence supporting that at least some of the genes induced are likely direct TF targets. For example, the knotted1 (kn1) motif is enriched in the promoters of genes induced by kn1 overexpression. In the next steps, we will continue the established workflow through the remainder of the cloned maize TFome, producing a resource for the maize community.