TRTech-PGR: Reprogramming the Plant Cell with Transcription Factors

A wide variety of cell lineage transformations has been achieved in biomedicine by ectopically expressing transcription factors (TFs) – providing insight into cell differentiation and allowing for the creation of medically-relevant cell types. A greater ability to reprogram plant cell fate and induce desirable pathways could have transformative impacts on plant tissue culture and synthetic biology. This project applies a new framework to systematically assess what can be accomplished with ectopic TF expression in maize, one of the most important US crops. Robotics-assisted assays will be used to test the effect of thousands of TFs on gene expression in parallel. This will be followed with targeted secondary screens to evaluate the physiological response to selected TFs in plant tissues. Ultimately, these experiments will contribute a greater understanding of TF function and a “reprogramming toolbox” to aid in the engineering of plant traits and development of improved plant breeding technologies. To connect research and education, a fellowship will be established to send graduate students and post-docs to speak about their careers at undergraduate institutions with a high proportion of underrepresented groups. Student fellows will be provided mentorship on speaking, and during their seminars will include information about exploring and navigating scientific careers. The scientific aims of this project are to: (1) measure the transcriptional response to a collection of 2000 cloned maize TFs using high-throughput protoplast assays; (2) establish methods to interpret and analyze these data, including approaches to connect TFs to target pathways, infer gene regulatory networks, and better account for technical covariates when analyzing high-throughput plate-based genomics data; and, (3) prioritize and test TFs for the ability to induce functional responses ectopically, with an emphasis on tissue regeneration – a crucial step in plant transformation. Data and code will be made accessible and free to use, including through data reports and graphical visualization on the gene landing pages of MaizeGDB. Plasmids will be distributed through the Arabidopsis Biological Resource Center (ABRC). Finally, the PIs will host an online workshop on high-throughput functional screening in plants, helping to make the technique available to the community. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.