In 1992 Science named Nitric Oxide (NO) Molecule of the Year.
Synthesis of Nitric Oxide - University of Reading
Drought is one of the most important abiotic stresses that causes significant reductions in crop yield and thus hinders the food security. Upon exposure to , plants exhibit a wide range of responses at the whole plant, cellular and molecular levels (; ; ). The NO-synthesizing activity in wheat plants was found to increase under drought conditions. The newly synthesized NO together with H2O2 participated in the regulation of ABA-induced closing of stomata in various plant species (). In addition, the protective role of NO in drought-stressed plants has been reported by several researchers. In a recent work, the activity of NOS in the cytosolic and microsomal fractions of maize leaves was determined (). The results showed that water stress induced increases in NOS activity in the cytosolic and microsomal fractions and the NOS activity in the microsomal fraction was higher and more susceptible to water stress treatment than that in the cytosolic fraction of maize leaves. It was observed that exogenously applied NO, reduced water loss from detached wheat leaves and seedlings subjected to drought conditions, decreased ion leakage and transpiration rate and induced stomatal closure, thereby enhancing plant tolerance to (). Interestingly, a specific NO scavenger, cPTIO, reverted the above actions of NO (). Results of this experiment suggest that exogenous application of NO donors might confer on plants an increased tolerance to severe conditions. It was shown that treatment of plants with exogenous NO enhanced drought tolerance of cut leaves and seedlings of wheat (). In addition, NO treatment enhanced wheat seedling growth and maintained relatively high water content and alleviated oxidative damage (). However, higher dose (2 mM SNP) aggravated the stress as a result of uncontrolled generation of ROS and ineffectiveness of antioxidant systems. Exogenous NO increased the activities of water stress induced subcellular antioxidant enzymes, which decreased accumulation of H2O2. These results suggest that NOS and NR are involved in water stress-induced NO production and NOS is the major source of NO. The potential ability of NO to scavenge H2O2 is at least in part due to the induction of a subcellular antioxidant defense mechanism. NO alleviates the ROS-mediated cytotoxic process in potato leaves (). The ROS-mediated damages caused by drought, including cell death, ion leakage and DNA fragmentation, were inhibited by exogenous NO and all of the protective effects were abolished by the treatment with PTIO (). The protective effect of NO in osmotic stress was recently confirmed in two ecotypes of reed suspension cultures. suggested that polyethylene glycol (PEG-6000) induced NO release in stress-tolerant but not sensitive ecotype reed, effectively protecting against oxidative damage and conferring an increased tolerance to osmotic stress (). In wheat seedlings, the osmotic stress produced by treatment with 0.4 M manitol reduced leaf water loss while increasing the leaf ABA content. These effects were partially reversed by NO scavengers and NOS activity inhibitors (). In tomato detached leaves, the application of NO donors inhibited the synthesis of proteinase inhibitor I and the generation of H2O2 in response to mechanical wounding ().
05/01/2018 · Synthesis of Nitric Oxide
Brief contents Chemistry and biochemistry of nitric oxide, Pharmacology of drug development, Nitric oxide and the respiratory and cardiovascular systems, Nitric oxide and brain functions, Subject index, Author index.