Interference between arsenic‐induced toxicity and hypoxia

Abstract

Plants often face combinatorial stresses in their natural environment. Here, arsenic (As) toxicity was combined with hypoxia (Hpx) in the roots of Arabidopsis thaliana as it often occurs in nature. Arsenic inhibited growth of both roots and leaves, whereas root growth almost entirely ceased in Hpx. Growth efficiently resumed, and Hpx marker transcripts decreased upon reaeration. Compromised recovery from HpxAs treatment following reaeration indicated some persistent effects of combined stresses despite lower As accumulation. Root glutathione redox potential turned more oxidized in Hpx and most strongly in HpxAs. The more oxidizing root cell redox potential and the lowered glutathione amounts may be conducive to the growth arrest of plants exposed to HpxAs. The stresses elicited changes in elemental and transcriptomic composition. Thus, calcium, magnesium, and phosphorous amounts decreased in rosettes, but the strongest decline was seen for potassium. The reorganized potassium-related transcriptome supports the conclusion that disturbed potassium homeostasis contributes to the growth phenotype. In a converse manner, photosynthesis-related parameters were hardly affected, whereas accumulated carbohydrates under all stresses and anthocyanins under Hpx exclude carbohydrate limitation. The study demonstrates the existence of both synergistic since mutually aggravating effects and antagonistic effects of single and combined stresses.

Remodeling of Root Growth Under Combined Arsenic and Hypoxia Stress Is Linked to Nutrient Deprivation

“…In fact, the combined stressed plants showed a lag in root growth recovery compared to individual treatments. Besides a unique and strong downregulation of many transcripts (>500), about 300 other transcripts increased in expression specifically under As and Hpx combination (Kumar et al, 2019). All these observations indicated existence of an energy efficient way to balance root stem cell division and differentiation in a way to best utilize the available resources for coping with nutrient deprivation and to facilitate sequestration of As for stress acclimation.…”

“…Root growth was severely inhibited during combined stress treatment; however, growth recovery was evident on reaeration (Kumar et al, 2019). In fact, the combined stressed plants showed a lag in root growth recovery compared to individual treatments.…”

“…Metabolic and molecular responses of Arabidopsis to a naturally prevalent combination of arsenic (As) and hypoxia (Hpx) were recently described by Kumar et al (2019). Arsenic contamination is a major problem linked worldwide to either groundwater or irrigation of rice cultivated in affected areas (Naujokas et al, 2013).…”

“…Application of HpxAs stress to Arabidopsis thaliana generated unique responses at physiological, transcriptomic, and metabolic level apart from certain overlapping changes (Kumar et al, 2019). Besides characterizing primary stress effects in the roots, it was possible to analyze the dynamics of rapid root-to-shoot communication (Kumar et al, 2019). The most challenging scenario that developed under HpxAs was strong deregulation of nutrient homeostasis.…”

The Expressions of Small Ubiquitin-like Modifier (SUMO) Related Genes Under Metal (Cu, Zn and Fe) Stress in Arabidopsis thaliana

“…After 2 days of germination period, 5 days old seedlings were treated with 50 µM Cu, 700 µM Zn and 400 µM Fe for 7 days. Metal concentrations were selected according to previous studies [21][22][23]. At the end of experiments whole seedlings were harvested, then flash frozen in liquid nitrogen and were stored at -80 °C until further analysis.…”