Role of Chemical Compounds in Abiotic Stress Mitigation


Chemical agents like hormones, osmoprotectants, antioxidants, and chelating agents for abiotic stress mitigation are substances or compounds that are applied to plants to help them survive or mitigate the deleterious effects of abiotic stresses. These chemical agents work through various mechanisms to enhance the plant's stress tolerance and improve its resilience. But last few years application of these chemical agents in agriculture has increased every year, the market is filled with products formulated using chemical agents.  In this blog, I try to explain in detail the mechanisms of these chemical agents and how they work in different abiotic stresses.

Phytohormones: Plant hormones play a crucial role in regulating plant responses to abiotic stresses. Phytohormones like ABA the most well-known hormone allied with abiotic stress responses, predominantly drought stress. It works by inducing stomatal closure, reducing water loss through transpiration, and conserving water in plant tissues. ABA also induces the expression of stress-responsive genes, stimulates the synthesis of osmoprotectants, and improves plant tolerance to drought, salinity, and cold stress. Jasmonates, including jasmonic acid and its derivatives signaling, activate the expression of stress-related genes, trigger the synthesis of protective compounds (such as antioxidants), and modulate stomatal closure and root growth to improve stress tolerance. Ethylene is a gaseous hormone synthesis that increases under stress conditions and regulates various adaptive responses. It promotes root growth, enhances the synthesis of protective compounds, and stimulates senescence and leaf abscission under stressful conditions. Cytokinins are hormones that regulate cell division, shoot development, and nutrient mobilization. Cytokinins can enhance root growth, delay senescence, and improve water and nutrient uptake efficiency, thereby increasing stress tolerance. Gibberellins are involved in regulating plant growth and development, including responses to abiotic stresses. They influence seed germination, shoot elongation, and flowering. Gibberellins can promote plant growth under stress conditions, help overcome growth inhibition caused by stress

Antioxidants: Abiotic stress can lead to the generation of reactive oxygen species (ROS) in plants, causing oxidative damage. Antioxidants help plants by scavenging reactive oxygen species (ROS) and protecting cellular structures from oxidative damage. Ascorbic Acid (Vitamin C) is a well-known antioxidant compound that scavenges ROS, including superoxide radicals and hydrogen peroxide, reducing their damaging effects on cellular components. Tocopherols (Vitamin E) are lipid-soluble antioxidants that act as chain-breaking antioxidants, inhibiting lipid peroxidation and maintaining membrane integrity under abiotic stress conditions. Glutathione is a tripeptide composed of cysteine, glutamic acid, and glycine. It helps neutralize ROS and acts as a cofactor for several antioxidant enzymes involved in detoxification processes. Some other antioxidant compounds are carotenoids, anthocyanin, and flavonoids protecting plant tissues from oxidative damage caused by abiotic stressors. Antioxidant enzymes, like superoxide dismutase (SOD), catalase (CAT), peroxidases, and glutathione reductase catalyze the breakdown of ROS and help maintain cellular redox balance. These antioxidant components work together to neutralize ROS and minimize oxidative damage in plant cells.

Osmoprotectants: Osmoprotectants are low molecular weight compounds that accumulate in plant cells under abiotic stress conditions, helping to maintain cellular osmotic balance and protect cellular structures. They act as compatible solutes, reducing water loss and stabilizing proteins and cell membranes. Common osmoprotectants Proline is one of the most widely studied osmoprotectants that helps maintain cellular water potential, stabilize proteins and membranes, scavenge ROS, and act as a molecular chaperone, Glycine betaine is a quaternary ammonium compound that accumulates in plants under osmotic stress contributes to osmotic adjustment, protects proteins and membranes, and stabilizes the structure and function of photosynthetic apparatus, Sugars, such as sucrose, glucose, and fructose help maintain cellular turgor, stabilize membranes, and protect proteins and enzymes, Sugars also serve as signaling molecules, regulating stress-responsive gene expression and metabolic processes. Polyols, such as mannitol and sorbitol, are sugar alcohols that maintain cellular osmotic balance, protect cellular structures, and scavenge ROS. Proline betaine, also known as betaine, is a quaternary ammonium compound that acts as osmoprotectant by protecting proteins and membranes, maintaining cellular water balance, and stabilizing enzyme activities.

Chelating Agents: Some abiotic stresses, such as heavy metal toxicity, can disrupt plant nutrient uptake and metabolism. Chelating agents, such as Ethylenediaminetetraacetic Acid (EDTA) is a synthetic chelating agent that forms stable complexes with a wide range of metal ions, including heavy metals such as lead, cadmium, and copper. By chelating these metal ions, EDTA helps to reduce their toxicity. Citric acid is a naturally occurring chelating agent that can form complexes with various metal ions, including iron, aluminum, and zinc. Citric acid enhances the solubility and availability of essential nutrients in the soil, making them more accessible for plant uptake. Humic substances enhance nutrient availability, improve soil structure, and promote plant growth. They also play a role in reducing heavy metal toxicity by chelating and immobilizing the metal ions, preventing their uptake by plants. Phytosiderophores are organic compounds secreted by certain plant species, primarily grasses, in response to iron deficiency. These compounds act as chelating agents for iron, forming stable complexes that can be easily taken up by plants.


Overall, these chemical agents can be applied as foliar sprays, seed treatments, or soil amendments to increase plant stress tolerance and improve overall plant health. Every chemical agent has a separate role in every plant growth stage and type of abiotic stress. Farmers are confused with products available in the market, and several times these products not working in field conditions. It’s our duty to provide farmers with good quality chemical agents and educate them about the use of those chemical agents.

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