A Toolkit of Programmable Salicylic Acid Regulated Transcription Factors to Engineer Plant Immune Responses

Pathogen damage limits crop yields around the world but it can be controlled with interventions at the genetic level. Classical breeding has been successful at broadening the range of pathogen receptors encoded in crop genomes. We would like to use synthetic biology to rationally redesign the stages of the plant immune response that act downstream of these receptors.

This poster charts our development of synthetic transcription factors responsive to salicylic acid (SA), one of the key plant immune system hormones. SA is produced in response to pathogen receptor activation and is responsible for triggering transcriptional reprogramming. SA acts through a transcriptional co-activator NPR1. SA regulation of NPR1 occurs via multiple parallel mechanisms, and the downstream binding partners of NPR1 receive inputs from other hormone pathways, introducing cross-talk. Both the complex relationship between SA and NPR1 activity and the complex downstream crosstalk are hurdles to rational engineering.

We are currently porting the machinery for SA dependent protein degradation from plants into budding yeast so that we can use yeast as a simple chassis to characterise degradation dynamics. A minimal SA degron will then be fused to a nuclease-null Cas9 to direct transcriptional responses in planta.