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Enzymatic and Non enzymatic Antioxidant mechanism to defend oxidative stressEnzymatic and nonenzymatic antioxidants in algae.ASC(Ascorbate),APX,(Ascorbate peroxidase),CAT Catalase, DHA Dehydroascorbate,GSH (Glutathione), GR Glutathione reductase , GSSG (Glutathione disulfide ),MDHA (Monodehydroascorbate ),SOD (Superoxide dismutase ),DHA (Dehydroascorbate).
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Plants respond to various stresses during their lifecycle among which abiotic stress is the most severe one comprising heat, cold, drought, salinity, flooding, etc. which take a heavy toll on crop yield worldwide in every corresponding year. ROS has a dual role in abiotic stress mechanisms where, at high levels, they are toxic to cells while at the...
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... accomplish ROS removal from plant system plants consists of several ROS scavenging system which can be categorized into enzymatic and non-n enzymatic defense mechanism. Plants contain various antioxidant enzymes to mediate ROS scavenging mechanism which includes superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione peroxidase (GPX), catalase (CAT), monodehydroascorbate reductase (MDHAR or MDAR), dehydroascorbate reductase (DHAR or DAR) and glutathione reductase (GR) (Figure 2). These antioxidant enzymes ensure plant survival by minimizing the deleterious effect of ROS and prevent its overaccumulation. ...
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... genes have been characterized into different classes such as protein kinases and phosphatases, transcription factors, enzymes, molecular chaperones, and other functional proteins. The different genes involved in the regulation of ROS homeostasis and response to abiotic stresses have been categorized in plants (Figure 3; Table 2). ...
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... ROS can degrade plant cells through the oxidation of membranes [54] and the degradation of molecules, such as DNA [55]. The production of these ROS is mainly associated with the reduction of stomatal conductance, which is regulated by the action of ABA through stress signaling from the roots [56]. Therefore, in the hybrids, when compared to the lines, the notable increase in secondary metabolites such as flavonoids (Flav) and anthocyanins (Anth) could potentially provide an adaptive advantage over the parent plants. ...
Nitrogen is crucial for plant growth and development, and improving nitrogen use efficiency (NUE) is a viable strategy for reducing dependence on nitrogen inputs and promoting sustainability. While the benefits of heterosis in corn are well known, the physiological mechanisms underlying this phenomenon in popcorn are less understood. We aimed to investigate the effects of heterosis on growth and physiological traits in four popcorn lines and their hybrids under two contrasting nitrogen conditions. We evaluated morpho-agronomic and physiological traits such as leaf pigments, the maximum photochemical efficiency of PSII, and leaf gas exchange. Components associated with NUE were also evaluated. N deprivation caused reductions of up to 65% in terms of plant architecture, 37% in terms of leaf pigments, and 42% in terms of photosynthesis-related traits. Heterosis had significant effects on growth traits, NUE, and foliar pigments, particularly under low soil nitrogen conditions. N-utilization efficiency was found to be the mechanism favoring superior hybrid performance for NUE. Non-additive genetic effects were predominant in controlling the studied traits, indicating that exploring heterosis is the most effective strategy for obtaining superior hybrids to promote NUE. The findings are relevant and beneficial for agro farmers seeking sustainable agricultural practices and improved crop productivity through the optimization of nitrogen utilization.
... It also modulates the physiological processes of the plants such as photosynthesis, respiration, leaf water potential, mineral absorption, circadian rhythm and hormone regulation etc. (Seleiman et al., 2021;Wang et al., 2021;Ghani et al., 2022;Hemati et al., 2022). Drought stress increases the production of reactive oxygen species (ROS) such as superoxide (O 2 -), singlet oxygen (O 2 ), hydrogen peroxide (H 2 O 2 ), and hydroxyl radicals (OH -) to levels that are frequently greater than the plant's scavenging capability (Chitara et al., 2017;Kumari et al., 2021;Sachdev et al., 2021). ROS damages cells and cellular components, impair physiological and biochemical processes and can even cause plant death (Xie et al., 2019). ...
Drought is a leading threat that impinges on plant growth and productivity. Nanotechnology is considered an adequate tool for resolving various environmental issues by offering avant-garde and pragmatic solutions. Using nutrients in the nano-scale including CaP-U NPs is a novel fertilization strategy for crops. The present study was conducted to develop and utilize environment-friendly urea nanoparticles (NPs) based nano-fertilizers as a crop nutrient. The high solubility of urea molecules was controlled by integrating them with a matrix of calcium phosphate nanoparticles (CaP NPs). CaP NPs contain high phosphorous and outstanding biocompatibility. Scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffraction analysis (XRD) were used to characterize the fabricated NPs. FE-SEM determined no areas of phase separation in urea and calcium phosphate, indicating the successful formation of an encapsulated nanocomposite between the two nano matrices. TEM examination confirmed a fiber-like structure of CaP-U NPs with 15 to 50 nm diameter and 100 to 200 nm length. The synthesized CaP-U NPs and bulk urea (0.0, 0.1% and 0.5%) were applied by foliar sprays at an interval of 15 days on pre-sowed VL-379 variety of finger millet (Eleusine coracana (L.) Gaertn.), under irrigated and drought conditions. The application of the CaP-U NPs significantly enhanced different plant growth attributes such as shoot length (29.4 & 41%), root length (46.4 & 51%), shoot fresh (33.6 & 55.8%) and dry weight (63 & 59.1%), and root fresh (57 & 61%) and dry weight (78 & 80.7%), improved pigment system (chlorophyll) and activated plant defense enzymes such as proline (35.4%), superoxide dismutase (47.7%), guaiacol peroxidase (30.2%), ascorbate peroxidase (70%) under both irrigated and drought conditions. Superimposition of five treatment combinations on drought suggested that CaP-U NPs at 0.5 followed by 0.1% provided the highest growth indices and defense-related enzymes, which were significantly different. Overall, our findings suggested that synthesized CaP-U NPs treatment of finger millet seeds improved plant growth and enzymatic regulation, particularly more in drought conditions providing insight into the strategy for not only finger millet but probably for other commercial cereals crops which suffer from fluctuating environmental conditions.
... It is well-acquainted fact that various redox and aerobic reactions in plant cellular organelles produce a considerable amount of ROS. However, under favorable conditions plant counteracts ROS production with various strategies to maintain redox homeostasis (Kumari et al. 2021). The lower ROS level within the cells can also act as secondary messengers that can participate in cell maintenance, division, differentiation, and organogenesis (Zeng et al. 2017;Fujita et al. 2006;Dvořák et al. 2021). ...
Reactive oxygen species (ROS) are the products of physiological metabolism in various cellular compartments such as mitochondria, peroxisomes, and chloroplasts. Under biotic and abiotic stress, ROS are significantly accumulated and can progressively induce oxidative damage and ultimately lead to cell death. Moreover, ROS generation is a fundamental process in plants to transmit and transport the signal toward the nucleus to increase tolerance against diverse conditions. The defense system against ROS not only consists of a scavenging system but is also comprised of an enzymatic and non-enzymatic defense system against various environmental issues. The enzymatic defense system against ROS includes various enzymes such as peroxidase (POD), superoxide dismutase (SOD), polyphenol oxidase (PPO), ascorbate peroxidase (APX), glutathione peroxidase (GPX), and catalase (CAT). This chapter covers a detailed study of the organelle-specific generation of ROS and existing enzymatic systems to balance the redox state. Moreover, the role of non-enzymatic and low-molecular-weight antioxidants in ROS detoxification and retrograde signaling will also be discussed. Plants have also evolved several interconnected signaling pathways to control the expression of different transcriptional factors and stress-responsive genes for producing various classes of proteins that result in stress regulation. More importantly, the relationship between ROS and epigenetic modifications to regulate gene expression will be precisely discussed in this chapter. Excess ROS accumulation can lead to the activation of cell death processes such as apoptosis which is crucial for plant development and survival. The role of apoptosis in maintaining normal cellular homeostasis under stress conditions is discussed in detail. In this chapter, the different mechanisms involved in ROS regulation that will offer a new platform for the improvement of abiotic stress tolerance in crops are summarized.KeywordsApoptosisEnzymatic antioxidantsGenesProteinsROS
... When the overproduction of ROS under stress conditions exceeds the cellular scavenging potential, the oxidative destruction of macromolecules, such as lipids and proteins, negatively impacts cellular metabolism leading to changes of membrane fluidity and ion transfer, loss of enzyme activities, inhibition of protein synthesis, damage of cellular components, and activation of a programmed cell death (Kumari et al., 2021). To minimize the oxidative injury, plants possess enzymatic and non-enzymatic antioxidants (AOXs) (Sharma et al., 2012). ...
In this review we summarize the current knowledge about the changes in Hypericum secondary metabolism induced by biotic/abiotic stressors. It is known that the extreme environmental conditions activate signaling pathways leading to triggering of enzymatic and non-enzymatic defense systems, which stimulate production of secondary metabolites with antioxidant and protective effects. Due to several groups of bioactive compounds including naphthodianthrones, acylphloroglucinols, flavonoids, and phenylpropanes, the world-wide Hypericum perforatum represents a high-value medicinal crop of Hypericum genus, which belongs to the most diverse genera within flowering plants. The summary of the up-to-date knowledge reveals a relationship between the level of defense-related phenolic compounds and interspecific differences in the stress tolerance. The chlorogenic acid, and flavonoids, namely the amentoflavone, quercetin or kaempferol glycosides have been reported as the most defense-related metabolites associated with plant tolerance against stressful environment including temperature, light, and drought, in association with the biotic stimuli resulting from plant-microbe interactions. As an example, the species-specific cold-induced phenolics profiles of 10 Hypericum representatives of different provenances cultured in vitro are illustrated in the case-study. Principal component analysis revealed a relationship between the level of defense-related phenolic compounds and interspecific differences in the stress tolerance indicating a link between the provenance of Hypericum species and inherent mechanisms of cold tolerance. The underlying metabolome alterations along with the changes in the activities of ROS-scavenging enzymes, and non-enzymatic physiological markers are discussed. Given these data it can be anticipated that some Hypericum species native to divergent habitats, with interesting high-value secondary metabolite composition and predicted high tolerance to biotic/abiotic stresses would attract the attention as valuable sources of bioactive compounds for many medicinal purposes.
... ASA and GSH are two vital antioxidants which can assist antioxidant enzymes in H 2 O 2 metabolism, thus scavenging ROS overproduction [44]. In this study, exogenous H 2 S application led to a significant increase in ASA and GSH contents during adventitious rooting under NaCl stress (Figure 7). ...
As a gas signal molecule, hydrogen sulfide (H2S) can enhance plant stress resistance. Here, cucumber (Cucumis sativus ‘Xinchun NO. 4’) explants were used to investigate the role of H2S in adventitious root development under salt stress. The results show that sodium chloride (NaCl) at 10 mM produced moderate salt stress. The 100 µM sodium hydrosulfide (NaHS) treatment, a H2S donor, increased root number and root length by 38.37% and 66.75%, respectively, indicating that H2S effectively promoted the occurrence of adventitious roots in cucumber explants under salt stress. The results show that under salt stress, NaHS treatment reduced free proline content and increased the soluble sugar and soluble protein content during rooting. Meanwhile, NaHS treatment enhanced the activities of antioxidant enzymes [peroxidase (POD), superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT)], increased the content of ascorbic (ASA) and glutathione (GSH), reduced the content of hydrogen peroxide (H2O2) and the rate of superoxide radical (O2−) production, and decreased relative electrical conductivity (REC) and the content of malondialdehyde (MDA). However, the NaHS scavenger hypotaurine (HT) reversed the above effects of NaHS under salt stress. In summary, H2S promoted adventitious root development under salt stress through regulating osmotic substance content and enhancing antioxidant ability in explants.
Nitric oxide (NO) is a signaling molecule which controls a variety of biological functions and plays important roles in plant physiology. NO is involved in the majority of plant responses to biotic and abiotic stress, either indirectly through gene activation or interaction with hormones and reactive oxygen species (ROS), or directly as a result of altering enzyme activities primarily through S-nitrosylation. Protein S-nitrosylation is a redox-based post-translational modification that involves covalent attaching of a NO molecule to a reactive cysteine thiol of a target protein. This modification performs many significant physiological functions of NO. However, S-nitrosylation is a conserved evolutionary mechanism that regulates various facts of cellular signaling such as hormone signaling and responses to pathogens. It is challenging to find S-nitrosylated proteins since the S-NO bond is labile and therefore, methods to identify these modified proteins becomes difficult under different pathological conditions. Biotin switch method is well known in identifying S-nitrosylated proteins. S-nitrosylation of proteins plays important role in regulating different cellular processes like signal transduction, autophagy, SUMOylation and also impacts pathogen’s virulence. However, much about S-nitrosylation is known due to abiotic stress. This short review highlights S-nitrosylation in response to biotic disturbances.
