介绍了Kirk—Othmer Encyclopedia of Chemical Technology（化工技术百科全书）（第五版）电子图书网络版数据库，并对该数据库使用方法和检索途径作出了说明，且结合实例简单地介绍了该数据库的检索方法。

Kirk-Othmer Encyclopedia of Chemical Technology数据库介绍及实例

Reactive oxygen species (ROS) generation is a usual phenomenon in a plant both under a normal and stressed condition. However, under unfavorable or adverse conditions, ROS production exceeds the capacity of the antioxidant defense system. Both non-enzymatic and enzymatic components of the antioxidant defense system either detoxify or scavenge ROS and mitigate their deleterious effects. The Ascorbate-Glutathione (AsA-GSH) pathway, also known as Asada–Halliwell pathway comprises of AsA, GSH, and four enzymes viz. ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase, play a vital role in detoxifying ROS. Apart from ROS detoxification, they also interact with other defense systems in plants and protect the plants from various abiotic stress-induced damages. Several plant studies revealed that the upregulation or overexpression of AsA-GSH pathway enzymes and the enhancement of the AsA and GSH levels conferred plants better tolerance to abiotic stresses by reducing the ROS. In this review, we summarize the recent progress of the research on AsA-GSH pathway in terms of oxidative stress tolerance in plants. We also focus on the defense mechanisms as well as molecular interactions.

https://www.mdpi.com/2076-3921/8/9/384/pdf

Regulation of Ascorbate-Glutathione Pathway in Mitigating Oxidative Damage in Plants under Abiotic Stress

Nanotechnology is a promising field of interdisciplinary research. It opens up a wide array of opportunities in various fields like medicine, pharmaceuticals, electronics and agriculture. The potential uses and benefits of nanotechnology are enormous. The current global population is nearly 7 */billion with 50% living in Asia. A large proportion of those living in developing countries face daily food shortages as a result of environmental impacts or political instability, while in the developed world there is surplus of food. For developing countries, the drive is to develop drought and pest resistant crops, which also maximize yield. The potential of nanotechnology to revolutionise the health care, textile, materials, information and communication technology, and energy sectors has been well publicized. The application of nanotechnology to agriculture and food industries is also getting attention nowadays. Investments in agriculture and food nanotechnologies carry increasing weight because their potential benefits range from improved food quality and safety to reduced agricultural inputs and improved processing and nutrition. While most investment is made primarily in developed countries, research advancements provide glimpses of potential applications in agricultural, food, and water safety that could have significant impacts on rural populations in developing countries. This review is concentrated on modern strategies used for the management of water, pesticides, limitations in the use of chemical pesticides and potential of nano-materials in sustainable agriculture management as modern approaches of nanotechnology. 
 
   
 
 Key words: Agriculture, nanotechnology, nanofertilizer, nanoencapsulation, nanoherbicides.

Nanotechnology in sustainable agriculture: Present concerns and future aspects

In plant cells the free radical nitric oxide (NO) interacts both with anti- as well as prooxidants. This review provides a short survey of the central roles of ascorbate and glutathione – the latter alone or in conjunction with S-nitrosoglutathione reductase – in controlling NO bioavailability. Other major topics include the regulation of antioxidant enzymes by NO and the interplay between NO and reactive oxygen species (ROS). Under stress conditions NO regulates antioxidant enzymes at the level of activity and gene expression, which can cause either enhancement or reduction of the cellular redox status. For instance chronic NO production during salt stress induced the antioxidant system thereby increasing salt tolerance in various plants. In contrast, rapid NO accumulation in response to strong stress stimuli was occasionally linked to inhibition of antioxidant enzymes and a subsequent rise in hydrogen peroxide levels. Moreover, during incompatible Arabidopsis thaliana-Pseudomonas syringae interactions ROS burst and cell death progression were shown to be terminated by S-nitrosylation-triggered inhibition of NADPH oxidases, further highlighting the multiple roles of NO during redox-signalling. In chemical reactions between NO and ROS reactive nitrogen species arise with characteristics different from their precursors. Recently, peroxynitrite formed by the reaction of NO with superoxide has attracted much attention. We will describe putative functions of this molecule and other NO derivatives in plant cells. Non-symbiotic hemoglobins (nsHb) were proposed to act in NO degradation. Additionally, like other oxidases nsHb is also capable of catalysing protein nitration through a nitrite- and hydrogen peroxide-dependent process. The physiological significance of the described findings under abiotic and biotic stress conditions will be discussed with a special emphasis on pathogen-induced programmed cell death.

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Nitric oxide, antioxidants and prooxidants in plant defence responses

Post-translational modifications (PTMs) mediated by nitric oxide (NO)-derived molecules have become a new area of research, as they can modulate the function of target proteins. Proteomic data have shown that ascorbate peroxidase (APX) is one of the potential targets of PTMs mediated by NO-derived molecules. Using recombinant pea cytosolic APX, the impact of peroxynitrite (ONOO-) and S-nitrosoglutathione (GSNO), which are known to mediate protein nitration and S-nitrosylation processes, respectively, was analysed. While peroxynitrite inhibits APX activity, GSNO enhances its enzymatic activity. Mass spectrometric analysis of the nitrated APX enabled the determination that Tyr5 and Tyr235 were exclusively nitrated to 3-nitrotyrosine by peroxynitrite. Residue Cys32 was identified by the biotin switch method as S-nitrosylated. The location of these residues on the structure of pea APX reveals that Tyr235 is found at the bottom of the pocket where the haem group is enclosed, whereas Cys32 is at the ascorbate binding site. Pea plants grown under saline (150 mM NaCl) stress showed an enhancement of both APX activity and S-nitrosylated APX, as well as an increase of H2O2, NO, and S-nitrosothiol (SNO) content that can justify the induction of the APX activity. The results provide new insight into the molecular mechanism of the regulation of APX which can be both inactivated by irreversible nitration and activated by reversible S-nitrosylation.

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Dual regulation of cytosolic ascorbate peroxidase (APX) by tyrosine nitration and S-nitrosylation

Effect of exogenous application of nitric oxide on salt stress responses of soybean

Salinity stress causes ionic stress (mainly from high Na⁺ and Cl⁻ levels) and osmotic stress (as a result of inhibition of water uptake by roots and amplified water loss from plant tissue), resulting in cell death and inhibition of growth and ultimately adversely reducing crop productivity In this report, changes in root nitric oxide content, shoot and root biomass, root H₂O₂ content, root lipid peroxidation, root cell death, root caspase-like enzymatic activity, root antioxidant enzymatic activity and root ascorbate and glutathione contents/redox states were investigated in maize (Zea mays L cv Silverking) after long-term (21 d) salt stress (150 mM NaCl) with or without exogenously applied nitric oxide generated from the nitric oxide donor 2,2'-(Hydroxynitrosohydrazano)bis-ethane In addition to reduced shoot and root biomass, salt stress increased the nitric oxide and H₂O₂ contents in the maize roots and resulted in elevated lipid peroxidation, caspase-like activity and cell death in the roots Altered antioxidant enzymatic activities, along with changes in ascorbate and glutathione contents/redox status were observed in the roots in response to salt stress The detrimental effects of salt stress in the roots were reversed by exogenously applied nitric oxide These results demonstrate that exogenously applied nitric oxide confers salt stress tolerance in maize by reducing salt stress-induced oxidative stress and caspase-like activity through a process that limits accumulation of reactive oxygen species via enhanced antioxidant enzymatic activity

Caspase-like enzymatic activity and the ascorbate-glutathione cycle participate in salt stress tolerance of maize conferred by exogenously applied nitric oxide

Nitric oxide synthase activity is required for development of functional nodules in soybean.

Exogenous nitric oxide limits salt-induced oxidative damage in maize by altering superoxide dismutase activity

Ascorbate peroxidase is one of the major enzymes regulating the levels of H2O2 in plants and plays a crucial role in maintaining root nodule redox status. We used fully developed and mature nitrogen fixing root nodules from soybean plants to analyse the effect of exogenously applied nitric oxide, generated from the nitric oxide donor 2,2′-(hydroxynitrosohydrazono)bis-ethanimine, on the enzymatic activity of soybean root nodule ascorbate peroxidase. Nitric oxide caused an increase in the total enzymatic activity of ascorbate peroxidase. The nitric oxide-induced changes in ascorbate peroxidase enzymatic activity were coupled to altered nodule H2O2 content. Further analysis of ascorbate peroxidase enzymatic activity identified three ascorbate peroxidase isoforms for which augmented enzymatic activity occurred in response to nitric oxide. Our results demonstrate that nitric oxide regulates soybean root nodule ascorbate peroxidase activity. We propose a role of nitric oxide in regulating ascorbate-dependent re...

Marshall Keyster

Papers

Effect of exogenous application of nitric oxide on salt stress responses of soybean

Caspase-like enzymatic activity and the ascorbate-glutathione cycle participate in salt stress tolerance of maize conferred by exogenously applied nitric oxide

Nitric oxide synthase activity is required for development of functional nodules in soybean.

Exogenous nitric oxide limits salt-induced oxidative damage in maize by altering superoxide dismutase activity

Nitric oxide increases the enzymatic activity of three ascorbate peroxidase isoforms in soybean root nodules