Detecting Genetic Variation in Plants by Mapping Cell Water Dynamics with Terahertz Laser Feedback Interferometry

This study investigated the use of terahertz (THz) imaging as a rapid, high-fidelity technique for discriminating between genetic variants of the Allium genus based on cellular water dynamics. It has been demonstrated earlier that plant genetic variations can be related to the biochemical and bio-mechanical alterations of the cell and that in turn they affect the water dynamics within the cell. In this article we show that the water dynamics, when considered in the form of the temporal evolution of the trajectory of the plant's response to terahertz radiation probe, and measured by a coherent terahertz transceiver, provides unique signature of the genetic makeup of the plant. Therefore by exploring these trajectories, we discriminate between closely related variants of the same genus. The technique used for THz probing was the laser feedback interferometry with THz quantum cascade lasers which enabled fast acquisition of high-resolution THz amplitude and phase images, which were processed into evaporation profiles describing the time-dependent dehydration of the samples. The trajectory of this profile in amplitude-phase reflectivity domain discriminates between different members of the Allium genus. This enables real-time genetic discrimination in agricultural and genome conservation applications.