Potassium deficiency stress tolerance in peanut (Arachis hypogaea) through ion homeostasis, activation of antioxidant defense, and metabolic dynamics: Alleviatory role of silicon supplementation

Potassium (K) scarcity of arable land is one of the important factors that hamper the growth of the plants and reduce yield worldwide. In the current study, we examine the physiological, biochemical, and metabolome response of Arachis hypogaea (GG7 genotype: fast-growing, tall, early maturing, and high yielding) under low K either solitary or in combination with Si to elucidate the ameliorative role of Si. The reduced fresh and dry biomass of peanut and photosynthetic pigments content was significantly alleviated by Si. Si application did not affect the leaf and stem K+, although it enhanced root K+ in K-limitation, which is probably due to up-regulated expression of genes responsible for K uptake. Si improves the potassium use efficiency in K-limitation as compared to control. K-deficiency increased MDA, O-2(center dot), and H2O2 levels in leaf and root of peanut. Si improved/ maintained the activity of antioxidative enzymes, which significantly lowered the ROS accumulation in K-limitation. The AsA/DHA and GSH/GSSG ratio was approximately unaffected in both leaf and root, suggesting the maintained cellular redox potential in K-starved peanut. Si promotes accumulation of sugars and sugar alcohols, phytohormones indicating their probable involvement in signal transduction, osmotic regulation, and improvement of stress tolerance. Down-regulation of aspartic acid and glutamic acid while up-regulation of lysine, histidine, and arginine could maintain charge balance in K-deprived peanut. The significant accumulation of polyphenols under K limitation supplemented with Si suggests the role of polyphenols for ROS scavenging. Our results demonstrated that Si as a beneficial element can mitigate K-nutrient toxicity and improve KUE of peanut under K-limitation conditions. Moreover, our results demonstrate that Si application can improve crop yield, quality, and nutrient use efficiency under nutrient limitation conditions.

Automated summary

Potassium scarcity is an important factor that hampers plant growth and reduces yield worldwide. This study examined the role of silicon (Si) in alleviating the negative effects of low potassium (K) on peanut plants. Results showed that Si application improved biomass production, photosynthetic pigments content, and potassium use efficiency. Si also reduced oxidative stress and maintained cellular redox potential in K-starved peanut plants. Furthermore, Si promoted the accumulation of sugars, sugar alcohols, and phytohormones, indicating their involvement in signal transduction and osmotic regulation. Additionally, Si application increased the accumulation of polyphenols, suggesting their role in scavenging reactive oxygen species. Overall, Si can mitigate K-nutrient toxicity and improve crop yield, quality, and nutrient use efficiency under nutrient limitation conditions.