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One of the most important factors in the regulation of plant responses to various environmental stresses is nitric oxide (NO). When wheat seedlings were grown in water with high osmotic pressure, we found that exogenous nitrogen oxides could reduce oxidative damage, increase proline accumulation, and increase photosynthesis in the leaves.
Plants use nitric oxide (NO) as a signalling molecule that has a wide range of physiological roles. Nonenzymatic and enzymatic methods are used to synthesise it in plant cells. It may also be cytotoxic at high concentrations due to its high reactivity. In addition, NO-derived chemicals may possibly play a role in these actions.
According to several recent studies, however, there is still a lack of understanding of NO’s role in photosynthesis and in photosynthesis performance. An overview of the role of exogenous NO in photosynthesis and ATP synthesis, particularly its effect on chlorophyll fluorescence characteristics, is presented here.
Effect of NO2 on Plants
The role of nitric oxide (NO) in preventing oxidative damage, which may help to maintain photosynthesis capacity and other major metabolic processes, as well as modulating root architecture and stomatal movement, is well documented. Exogenous synthetic NO donors, genetic manipulation, interactions with microorganisms (mycorrhizas, plant-growth-promoting bacteria), and/or changes in endogenous synthesis and scavenger mechanisms can all be used to manipulate NO levels. Genetic modification is also an option.
When it comes to dealing with various types of stress, the body still relies on NO and ROS signalling. In spite of the fact that abiotic stresses have frequently but not always been recorded, the precise pathways involved in NO signalling for each individual stress state are just now beginning to emerge.
Photosynthesis and Nitric Oxide
Because it is lipophilic, nitrite oxide (NO) readily diffuses in the body. In many parts of the world, drought is the most significant environmental factor restricting crop growth. It is common to see a decline in photosynthesis and growth when plants are under water stress. An imbalance in the formation of reactive oxygen species (ROS) and antioxidant defences causes oxidative damage to plant cells, resulting in detrimental consequences.
Consequently, the ability to detoxify reactive oxygen species increased the drought tolerance of plants. The quick buildup of suitable osmolytes like Glycinebetain and proline may help plants cope with osmotic stress caused by water deficiency.
A growing number of evidence pieces suggest that NO is an essential signal molecule in plant responses to both natural and man-made stressors. Studies reveal that phytohormones influence plant development and stress responses by increasing the production of nitric oxide synthase (NO). The antioxidant enzymes were stimulated as a result of the ABA triggering NO generation. It has been shown that polyamine promoted NO production in specific tissues of Arabidopsis seedlings, particularly in the root tips and primary leaves.
It is common for plants to be subjected to a variety of abiotic stresses at various points in their life cycle. As protection against stress, plants emit signalling molecules that trigger a cascade of stress-adaptation responses leading either to programmed cell death or plant acclimation. In plants, the redox signalling molecule nitric oxide (NO) is involved in a variety of physiological processes, including germination, development, flowering, and senescence, as well as abiotic stress. NO is a small molecule but an important one in plants.
A number of studies have shown a positive association between the buildup of NO in plants under stress and the amount of stress they are under. An overview of NO biosynthesis, sources, and exogenous application of NO donors under stress from salt and heavy metals is presented here. NO is synthesised in the body. Exogenous NO alleviates the deleterious effects of stress on plants and enhances antioxidant activity in most plant species.
NO is also involved in the posttranslational modifications of S-nitrosylation and tyrosine nitration. A plant’s ability to withstand a wide range of stressors depends on a variety of elements, such as the type of plant. Research into how NO affects crops under stress situations is intended to aid in the efficient exploitation of crops.
Conclusion
Plants can acquire nitric oxide either endogenously or from the atmosphere and soil around them. It’s interesting to note that the level of this gaseous free radical is far from constant and changes widely throughout tissues depending on the ontogeny of a certain plant and fluctuations in the environment. Integration of plant hormone action with antioxidant networks and the control of reactive oxygen and nitrogen species concentrations are necessary for proper plant growth, vegetative development, and reproduction.
Adaptive responses are essential for plants because they are frequently subjected to abiotic stress conditions such as limited nutrition availability, salt, drought, intense ultraviolet (UV) radiation, and extreme temperatures. Nitric oxide (NO) plays an important role in plants’ ability to adapt to and survive under environmental stress circumstances by functioning as an intermediary between hormones and reactive oxygen species (ROS). ATP synthesis is also directly related to NO.
