Modeling of Synthetic Biology-Based Plant Sensors

Synthetic biology-based plant sensors detect plant responses to either biotic or abiotic stress. The sensing can be due to the response of a promoter gene activating a reporter gene, expressing a protein that activates - directly or indirectly - a signal output mechanism. The promoter-reporter operation can be a single-stage response or a multiple-stage one, where, for example, the expressed protein of the first stage activates another promoter gene. The output signal can be optical, electrical, or electrochemical. The sensor can be a multiple-input/multiple-output device and include control elements, such as a genetic optical switch, or feedback mechanisms for reducing background noise and improving signal-to-noise ratio. Next is the transducer, converting the biological signal to an electrical signal for further signal processing, analog to digital conversion, storage, and network communication. The modeling of each of the stages: whole-cell sensing, protein expression and signal transduction, and CMOS interfacing, is presented, and a unified approach is proposed allowing for complete system modeling using Verilog-A hardware description language (HDL).