Optimization of Potassium Supply under Osmotic Stress Mitigates Oxidative Damage in Barley

Abstract

Potassium (K) is the most abundant cation in plants, playing an important role in osmoregulation. Little is known about the effect of genotypic variation in the tolerance to osmotic stress under different K treatments in barley. In this study, we measured the interactive effects of osmotic stress and K supply on growth and stress responses of two barley cultivars (Hordeum vulgare L.) and monitored reactive oxygen species (ROS) along with enzymatic antioxidant activity and their respective gene expression level. The selected cultivars (cv. Milford and cv. Sahin-91Sahin-91) were exposed to osmotic stress (−0.7 MPa) induced by polyethylene glycol 6000 (PEG) under low (0.04 mM) and adequate (0.8 mM) K levels in the nutrient solution. Leaf samples were collected and analyzed for levels of K, ROS, kinetic activity of antioxidants enzymes and expression levels of respective genes during the stress period. The results showed that optimal K supply under osmotic stress significantly decreases ROS production and adjusts antioxidant activity, leading to the reduction of oxidative stress in the studied plants. The cultivar Milford had a lower ROS level and a better tolerance to stress compared to the cultivar Sahin-91. We conclude that optimized K supply is of great importance in mitigating ROS-related damage induced by osmotic stress, specifically in drought-sensitive barley cultivars.

Functional Dissection of the Physiological Traits Promoting Durum Wheat (Triticum durum Desf.) Tolerance to Drought Stress

“…Thus, we suggest that the high accumulation of proline and K in shoots participates in maintaining leaf hydration, key metabolic reactions (photosynthesis …), and plant growth. This suggestion is confirmed by the results of Tavakol et al [ 33 ], who reported that K is the most abundant cation in plants, playing an important role in osmoregulation. When drought stress occurs, the availability of plant nutrients is decisive in plant stress adaptation and avoidance.…”

“…Potassium is the most abundant cation in plants and affects the osmotic potential of plant cells, consequently playing a crucial role in stress mitigation [ 30 ]. Adequate K availability under osmotic stress improves plant water uptake, and water use efficiency decreases the ABA content, and avoids limitations in stomatal conductance and assimilation [ 33 , 55 , 56 ]. Otherwise, Chowdhury et al [ 36 ] reported higher capacities of proline accumulation in the tolerant genotypes of wheat, BAW1158 and BAW 1169, subjected to drought stress.…”

“…Tränkner et al [ 30 ] reported that K plays a crucial role in stress mitigation. Tavakol et al [ 33 ] demonstrated that K is the most abundant cation in plants, playing an essential role in osmoregulation.…”

Genome-wide identification and multiple abiotic stress transcript profiling of potassium transport gene homologs in Sorghum bicolor

“…Also, long-term exposure to water deficit conditions led to leaf damage due to ROS formation (Wang et al, 2013). In support of this, optimization of K + supply mitigates the damage caused due to the oxidative stress in barley exposed to drought stress (Tavakol et al, 2021). Silencing HvAKT2 and HvHAK1 in barley enhanced the ROS (H 2 O 2 ) production in PEG-treated leaves (Feng et al, 2020a).…”

Potassium application enhances drought tolerance in sesame by mitigating oxidative damage and regulating osmotic adjustment

“…A fresh leaf sample (0.3 g) was homogenized in 5 ml of 50 mM of phosphate buffer (pH 7.0) and 10 g L −1 of polyvinylpyrrolidone and centrifuged at 15,000×g for 20 min, and then the supernatants were collected as a crude extraction for enzyme activity determinations. 1) SOD (EC 1.15.1.1) activity was determined by monitoring the inhibition of photochemical reduction of Nitro blue tetrazolium (NBT) according to Tavakol et al (2021). 2) CAT (EC 1.11.1.6) activity was measured by the ammonium molybdate method (Djanaguiraman et al, 2009).…”