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Nitric oxide sensing in plants is mediated by the N-end rule of proteolysis [61] [62] and controls abiotic stress responses such as flooding-induced hypoxia, [63] salt and drought stress. [64] [65] [66] Nitric oxide interactions have been found within signaling pathways of plant hormones such as auxin, [67] ethylene, [63] [68] [69] Abscisic ...
Nitric oxide synthases (EC 1.14.13.39) (NOSs) are a family of enzymes catalyzing the production of nitric oxide (NO) from L-arginine. NO is an important cellular signaling molecule. It helps modulate vascular tone , insulin secretion, airway tone, and peristalsis , and is involved in angiogenesis and neural development.
When the plant is under stress, instead of reducing nitrate via NR to be incorporated into amino acids, the nitrate is reduced to nitric oxide which can have many damaging effects on the plant. Thus, the importance of regulating nitrate reductase activity is to limit the amount of nitric oxide being produced.
Competing with its formation, superoxide is destroyed by the action of superoxide dismutases, enzymes that catalyze its disproportionation: 2 O − 2 + 2H + → O 2 + H 2 O 2. hydrogen peroxide (H 2 O 2) is also produced as a side product of respiration. [4] Peroxynitrite (ONO − 2) results from the reaction of superoxide and nitric oxide.
Nitrification is the biological oxidation of ammonia to nitrate via the intermediary nitrite. Nitrification is an important step in the nitrogen cycle in soil. The process of complete nitrification may occur through separate organisms [ 1 ] or entirely within one organism, as in comammox bacteria.
The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmospheric, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation ...
Biological nitrogen fixation (BNF) occurs when atmospheric nitrogen is converted to ammonia by a nitrogenase enzyme. [1] The overall reaction for BNF is: N2 + 16ATP + 16H2O + 8e− + 8H+ → 2NH3 +H2 + 16ADP + 16Pi. The process is coupled to the hydrolysis of 16 equivalents of ATP and is accompanied by the co-formation of one equivalent of H.
In plants, polyamines have been linked to the control of senescence [60] and programmed cell death. [61] Nitric oxide (NO) – serves as signal in hormonal and defense responses (e.g. stomatal closure, root development, germination, nitrogen fixation, cell death, stress response). [62]