Introduction

Plant-based sensors are physiology-based mechanisms—either already present or artificially engineered to create “smart” plants—capable of reporting the presence of specific chemical, pathogen, and radiation stimuli on land. Physiology-based mechanisms that are artificially integrated into plants by gene-editing techniques are a part of a broader effort to create bio-sensors. Plant-based sensors are comprised of two elements. The first includes the plant’s physiological mechanisms and physical responses that are either genetically modified or left untouched (“natural”) and react to a specific compound or environmental condition. These smart plant physical reactions must then be remotely measured to determine the presence or lack of stimuli. The second element is comprised of remote, man-made technology that monitors the smart plants’ reactions and provides data that is interpretable to an operator.

The technology necessary to monitor plant physiology-based mechanism, responses, and physical reactions already exists. For example, a number of existing technologies can monitor plant growth, leaf coverage, chemical composition, visible and infrared light reflectance and the temperature of plants and soil.1 These measurement devices are necessary to collect data from reporting smart plants unobtrusively and remotely. These biosensors represent a novel and promising long-term intelligence source that is resilient, stealthy, unobtrusive, and easy to distribute. Biosensors can be genetically modified to detect multiple and diverse stimuli and can be integrated into many different plants found in varying biomes and regions. Modified plants could be distributed by means of wind or wildfires, water, animals, or mechanical and non-mechanical human activity. For example, seeds of modified plants could have parachutes similar to those of poplar seeds, which have been found to travel up to 30 km; alternatively, seeds could have floating capabilities allowing them to disperse through rivers.2 Bio-sensor projects seek to substitute costly and intrusive monitoring efforts for conventional and nuclear weapon presence and development. Currently, genetically modified plants have been able to sense and report single types of low concentration airborne molecules, such as TNT.3 The ability of these plants to devote resources to sense and report multiple complex chemical compounds and radiation long-term while surviving in wild environments has not been established.

  1. Nikolaos Katsoulas et al., “Crop Reflectance Monitoring as a Tool for Water Stress Detection in Greenhouses: A Review,” Biosystems Engineering 151 (November 2016): 374-398. ↩

  2. W. Carter Johnson et al., “Modeling Seed Dispersal and Forest Island Dynamics,” in Ecological Studies Forest Island Dynamics in Man-Dominated Landscapes, R.L. Burgess and D.M. Sharpe, eds. (December 1981), 215-39; Jeremy H. Groves et al., “Modelling of Floating Seed Dispersal in a Fluvial Environment,” River Research and Applications, 2009, no. 25 (2009): 582-92. ↩

  3. Mauricio Antunes et al., “Programmable Ligand Detection System in Plants through a Synthetic Signal Transduction Pathway,” PLOS ONE 6, no. 1 (January 2011): 1-11. ↩

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