Root System Architecture Plasticity of Bread Wheat in Response to Oxidative Burst under Extended Osmotic Stress

Abstract

There is a demand for an increase in crop production because of the growing population, but water shortage hinders the expansion of wheat cultivation, one of the most important crops worldwide. Polyethylene glycol (PEG) was used to mimic drought stress due to its high osmotic potentials generated in plants subjected to it. This study aimed to determine the root system architecture (RSA) plasticity of eight bread wheat genotypes under osmotic stress in relation to the oxidative status and mitochondrial membrane potential of their root tips. Osmotic stress application resulted in differences in the RSA between the eight genotypes, where genotypes were divided into adapted genotypes that have non-significant decreased values in lateral roots number (LRN) and total root length (TRL), while non-adapted genotypes have a significant decrease in LRN, TRL, root volume (RV), and root surface area (SA). Accumulation of intracellular ROS formation in root tips and elongation zone was observed in the non-adapted genotypes due to PEG-induced oxidative stress. Mitochondrial membrane potential (∆Ψm) was measured for both stress and non-stress treatments in the eight genotypes as a biomarker for programmed cell death as a result of induced osmotic stress, in correlation with RSA traits. PEG treatment increased scavenging capacity of the genotypes from 1.4-fold in the sensitive genotype Gemmiza 7 to 14.3-fold in the adapted genotype Sakha 94. The adapted genotypes showed greater root trait values, ∆Ψm plasticity correlated with high scavenging capacity, and less ROS accumulation in the root tissue, while the non-adapted genotypes showed little scavenging capacity in both treatments, accompanied by mitochondrial membrane permeability, suggesting mitochondrial dysfunction as a result of oxidative stress.

Ectopic Expression of a Wheat R2R3-Type MYB Gene in Transgenic Tobacco Enhances Osmotic Stress Tolerance via Maintaining ROS Balance and Improving Root System Architecture

“…: 251520, Sigma-Aldrich Chemical Co., St. Louis, MO, USA). DCFH-DA (0.25 µM) in 1x PBS buffer solution was used as described by Azab et al [22]. After 30 min of incubation, the roots were washed twice with PBS buffer and imaged using a fluorescence microscope (Nikon Eclipse 80i, Tokyo, Japan) and with filter set 10 (excitation 485 nm; emission: 530 nm).…”

“…Our previous study showed that an adapted root in wheat (Triticum aestivum) was correlated with high antioxidant ability [22]. The R2R3-MYB TaMYB20 was found to be a key factor in drought tolerance [23] and to display antioxidant activity preventing oxidative damage [19].…”

Plasticity of Morpho-Physiological Traits and Antioxidant Activity of Hydroponically Sprouted Hordeum vulgare L. When Using Saline Water

“…The experiment consisted of three treatments (control, S1 and S2) with three replicates for each genotype. The sampling of roots was carried out by randomly selecting one seedling from each genotype from each box; toluidine red was used to stain the roots, as described by [29]. Then, the roots were spread on a glass sheet, and the excess staining solution was removed carefully using tissue paper.…”

“…Functionally, plant roots are characterized by the presence of a meristematic and elongation zone, in which the rate of cell division is high and reactive oxygen species (ROS) serve as signaling molecules, which is the same as the functional role of hormones [28]. The overproduction of ROS is potentially harmful as they are regarded as the regulators of cellular component damage and irreparable metabolic dysfunction, which consequently results in mitochondrial dysfunction and programed cell death [29]. The enzymatic activity of superoxide dismutase in wheat plants results in primary root elongation under osmotic stress [30].…”