Drought monitoring in tobacco plants by in-vivo electrochemical biosensor

Real-time monitoring along with early detection of drought levels was studied in transgenic tobacco plants using an in-vivo technique with a bio-electrochemical sensor. This study reports on the detection of the plant's water deficit status as indicated by its reporter gene expression, caused due to drought stress. Plant-based in-vivo sensing provides real-time information generated by the actual hydration/dehydration status of the plant; It complements the information provided by ex-vivo sensors sampling the plant's surroundings. In the method described here, the expression of the β-D-glucuronidase enzyme, expressed under drought conditions in genetically modified tobacco plants, is monitored using the enzyme-substrate (4-nitrophenyl β-D-glucuronide) reaction generating an electrochemically active product. The generated product is oxidized on the working electrode of a three-electrode electrochemical cell-on-chip mounted on the leaves of Nicotiana tabacum plants. The transport mechanisms and the real-time behavior of enzyme activity was studied using the Michaelis-Menten kinetic diffusion model. The obtained electrochemical signals fit the Michaelis-Menten diffusion kinetic model with the mean absolute error below 5%. The proposed bioelectrochemical sensor detected drought stress earlier than other conventional methods. The sensor applicability under dehydration periods up to 3 weeks is demonstrated showing the highlight and problems of this method.