Cadmium- and Flood-Induced Anoxia Stress in Pea Roots Measured by Electrical Impedance

Abstract

Electrical impedance measurement -complex resistance in the presence of alternating current -is a useful tool for the investigation of structural characteristics of solid materials but also for plant tissues. This measurement is easily done: only two electrodes are inserted into the plant tissue, so it can be considered as a non-invasive technique and it may be a successful method for detecting structural changes in plants caused by environmental stresses. The effects of fl ood and cadmium stress were investigated by electrical impedance measurement, because both of them cause structural changes in plant tissues. Apoplasmic resistance (Ra), symplasmic resistance (Rs), and membrane capacitance (Cm) of pea roots were calculated. In the fi rst fi ve days of fl ood treatment, the Rs and Cm values of roots decreased drastically. In case of cadmium treatment, the Rs and Cm values of roots showed an increasing tendency supposedly as a consequence of the enhanced membrane rigidity, the thickened cell walls and decreased growth phenomena caused by the heavy metal. There also was a remarkable difference in cadmium accumulation patterns and in the changes of the calculated parameters amongst anoxic and aerated seedlings. This initial work revealed that the development of stress caused by two environental stress agents, cadmium and fl ood, can be followed by electrical impedance measurement.

Application of impedance spectroscopy and conductometry for assessment of varietal differences in wheat

“…Impedance data were readily used for characterization of changes in plant tissues under stress conditions (Zhang et al 2002;Jócsák et al 2009). Lately, impedance spectroscopy was applied by Mizukami et al (2007) to monitor leaf growth.…”

“…Thus far, a large body of experimental techniques has been employed to discriminate between intact and stressed plant species (Bajji et al 2002;de Faria et al 2013;Jócsák et al 2009;Mancuso et al 2004;Repo et al 2000). However, the question of distinguishing untreated samples of different varieties is challenging in no lesser extent.…”

“…This allowed the uniform plant tissue to be represented by specific models including extracellular resistance, plasma membrane capacitance, cytoplasmic resistance, tonoplast capacitance, and vacuole interior resistance (Zhang and Willison 1991). The impedance data were used to characterize plant tissues and their changes during stress (Zhang et al 2002;Jócsák et al 2009). EIS was also employed to monitor moisture content and growth of tea leaves (Mizukami et al 2006(Mizukami et al , 2007.…”

Electrical characterization of the root system: a noninvasive approach to study plant stress responses

“…water (ε r ~ 80) or cellulose (ε r ~ 7.6; Ellis et al 2013). Therefore, the increased amount of these materials deposited in cell walls under stress results in reduced |Φ R | and enhanced R in the roots (Jócsák et al 2010). Stress is observed to weaken the electrical double layers present in the root, decreasing the magnitude of the overall polarization response (Weigand and Kemna 2017).…”

“…Environmental stress is reported to cause changes in the electrical properties of plant tissues by modifying numerous features of cell walls, membranes, and the cytosol (Jócsák et al 2010;Khaled et al 2018). For this reason, impedance spectroscopy has become an effective method to study plant responses to, e.g., freeze injury, high salinity, or nutrient stress at the cellular level, using a wide frequency range (Hz-MHz) in isolated tissues and organs (Repo et al 2000;Hamed et al 2016;Li et al 2017).…”