Electrical impedance tomography as a tool for phenotyping plant roots

Abstract

Background Plant roots are complex, three-dimensional structures that play a central role in anchorage, water and nutrient acquisition, storage and interaction with rhizosphere microbes. Studying the development of the plant root system architecture is inherently difficult as soil is not a transparent medium. Results This study uses electrical impedance tomography (EIT) to visualise oilseed rape root development in horticultural compost. The development of healthy, control plants and those infected with the gall-forming pathogen, Plasmodiophora brassicae —the causative agent of clubroot disease—were compared. EIT measurements were used to quantify the development of the root system and distinguish between control and infected plants at the onset of gall formation, approximately 20 days after inoculation. Although clear and stark differences between healthy and infected plants were obtained by careful (and hence laborious) packing of the growth medium in layers within the pots; clubroot identification is still possible without a laborious vessel filling protocol. Conclusions These results demonstrate the utility of EIT as a low-cost, non-invasive, non-destructive method for characterising root system architecture and plant-pathogen interactions in opaque growth media. As such it offers advantages over other root characterisation techniques and has the potential to act as a low-cost tool for plant phenotyping. Electronic supplementary material The online version of this article (10.1186/s13007-019-0438-4) contains supplementary material, which is available to authorized users.

Sensing the electrical properties of roots: A review

“…We limit ourselves to low-frequency electrical methods, from direct current (DC) to a few tens of kilohertz, due to their potential to investigate individual fine crop roots (diameter <1 mm). Recent reviews focused on imaging of root zone processes (Corona-Lopez, Sommer, Rolfe, Podd, & Rieve, 2019;Zhao et al, 2019), whereas others provided a short summary of the F I G U R E 1 Schematic illustration of (a) the plant cell, showing some of the organelles (vacuole, nucleus, and nuclear membranes), the cell wall, and the three-layer (protein-lipid-protein) cell membrane. The frequency-dependent current paths through plant tissues, showing (b) low-frequency current pathway and (c) high-frequency current pathway.…”

Crop Phenomics and High-Throughput Phenotyping: Past Decades, Current Challenges, and Future Perspectives

“…But both the core-break and minirhizotrons methods can only detect limited roots, and the root measurements were subject to the sample positions. Some nondestructive detection methods, such as ground-penetrating radar (Delgado et al, 2017) and electrical impedance tomography (Corona-Lopez et al, 2019), could be used to phenotype root biomass and root development. However, the spatial resolution of both methods is much lower ($cm/pixel), and it is hard to detect individual fine roots.…”

Freezing resistance evaluation of rose stems during frost dehardening using electrical impedance tomography

“…For the EIT images of rose stems at different temperatures, the EIT image reconstruction was based on the data acquisition system of The Fourth Military Medical University [31], EITMonitor image reconstruction software [32], the methods of EIT as a tool for phenotyping plant roots [10], and a real-time EIT imaging system based on the split augmented Lagrangian shrinkage algorithm [33]. The data acquisition system included a multiplexer, analogue to digital converter, and micro-programmed control unit, among other components [31] (see Fig.…”

“…In 1978, Henderson and Webster [4] applied the EIT technique to the study of pulmonary oedema and generated the rst impedance image. Since then, the EIT technique has developed rapidly, especially in the medical eld and in root system [5][6][7][8][9][10][11], but the EIT technique has rarely been applied in plant science, particularly to study plant resistance to abiotic and biotic stresses. According to Bera [12], under alternating electrical excitation, biological tissues produce complex electrical impedance that depends on tissue composition, structures, health status, and applied signal frequency, and hence the bioelectrical impedance methods can be utilized for non-invasive tissue characterization.…”