AUTHOR=Persad-Russell Ramona , Mazarei Mitra , Schimel Tayler Marie , Howe Lana , Schmid Manuel J. , Kakeshpour Tayebeh , Barnes Caitlin N. , Brabazon Holly , Seaberry Erin M. , Reuter D. Nikki , Lenaghan Scott C. , Stewart C. Neal 

TITLE=Specific Bacterial Pathogen Phytosensing Is Enabled by a Synthetic Promoter-Transcription Factor System in Potato

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.873480

DOI=10.3389/fpls.2022.873480

ISSN=1664-462X

ABSTRACT=At present, most remote sensing platforms for early detection of plant diseases utilize hyperspectral imaging devices. This approach is limited by the lack of signal specificity.  Detection of spectral reflectance is also affected by environmental factors. Here, we addressed these drawbacks using synthetic biology to engineer an inducible pathogen-specific phytosensor with a fluorescence reporter transgene; enabling phytosensor plants to function as real-time monitoring biological devices. We demonstrated a phytosensor with improved sensing to specific bacterial pathogens, and targeted detection using spectral wavelengths specific to a fluorescence reporter. Previous attempts to create phytosensors revealed limitations in using innate plant promoters with low inducible activity, since they are not sufficient to produce a strong detectable fluorescence signal for remote sensing. To address this, we designed a pathogen-specific phytosensor as a synthetic promoter-transcription factor system; using the S-Box cis-regulatory element which has low inducible activity as a synthetic 4xS-Box promoter, and the Q-system transcription factor as an amplifier of reporter gene expression. We demonstrated that this promoter-transcription factor system resulted in 6-fold amplification of the fluorescence signal post-pathogen infection. In addition, we demonstrated that it was possible to remotely sense the enhanced phytosensor at a distance of three meters, with a reporter amplification signal detected as early as 24 hours post-bacterial infection. This novel bacterial pathogen-specific phytosensor potato plant demonstrates that the Q-system may be leveraged as a powerful orthogonal tool to amplify a weak pathogen-inducible promoter, enabling remote detection of a previously undetectable fluorescence signal. Remote sensing of pathogen-specific phytosensors would be an important asset for real-time early defense against diseases that cause crop damage.