Time-resolved chemical monitoring of whole plant roots with printed electrochemical sensors and machine learning

Abstract

Traditional single-point measurements fail to capture dynamic chemical responses of plants, which are complex, nonequilibrium biological systems. We report TETRIS ( t ime-resolved e lectrochemical t echnology for plant r oot environment i n s itu chemical sensing), a real-time chemical phenotyping system for continuously monitoring chemical signals in the often-neglected plant root environment. TETRIS consisted of low-cost, highly scalable screen-printed electrochemical sensors for monitoring concentrations of salt, pH, and H 2 O 2 in the root environment of whole plants, where multiplexing allowed for parallel sensing operation. TETRIS was used to measure ion uptake in tomato, kale, and rice and detected differences between nutrient and heavy metal ion uptake. Modulation of ion uptake with ion channel blocker LaCl 3 was monitored by TETRIS and machine learning used to predict ion uptake. TETRIS has the potential to overcome the urgent “bottleneck” in high-throughput screening in producing high-yielding plant varieties with improved resistance against stress.

Plant-on-a-chip: continuous, soilless electrochemical monitoring of salt uptake and tolerance among different genotypes of tomato

“…We have previously observed a similar effect in kale seedlings for multiple salts with a range of ions (including sodium salts, heavy metal salts and nutrients), and TETRIS is not limited to just measuring changes in [NaCl]. 28 To compare this observed uptake between experiments, the rate of uptake, k uptake , was calculated by taking the gradient of the slope in the log( Z ) vs. t plot ( Fig. 1D ).…”

“…1A ). 28 The chamber comprised a transparent acrylic lid and silicone base with water reservoir, allowing the plant to photosynthesize whilst maintaining a constant humidity. Screen-printed electrodes on polyester transparency sheet were affixed to a raised platform, placed into the measurement chamber and connected to a potentiostat (PalmSens 4 by PalmSens BV, Netherlands).…”

“… 11,42–46 pH sensors have previously been used in TETRIS to elucidate pH effects of uptake in kale. 28 Ion-selective electrodes, such as for K + , Ca 2+ and Na + could be used to decouple the non-specific uptake measured by the impedance sensors in TETRIS and differentiate difference in uptake. 47,48 …”

“…We have previously shown that TETRIS can be adapted for use in agar, commonly used in plant experiments for Arabidopsis thaliana. 28,40 An impedance sensor can be embedded into the agar growth medium and monitor as ions are taken up by plants. Theoretically, TETRIS would be compatible with other soilless systems, as long as there is sufficient solution in contact with the electrodes.…”

Parallel, Continuous Monitoring and Quantification of Programmed Cell Death in Plant Tissue

“…While different methods have their own advantages and are often used in conjunction with each other as confirmatory measures of HR, few are suitable for high throughput, sensitive, and continuous measurement. [ 21 , 22 ] Staining techniques are typically both time and labor‐intensive, can involve the handling of toxic chemicals, and each stained tissue sample provides data for only a single time point. High throughput image acquisition has been demonstrated with fluorescence imaging of whole leaves, [ 17 ] but as with other optical techniques, quantification/scoring is not fully automated and requires manual processing.…”