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\"The citrus industry is one of the world's most important fruit production industries, but global climate change, pests, diseases, and improper handling are affecting plant yields. CitrusProduction: Technological Advancements and Adaptation to Changing Climate presents information on advancements in the citrus industry examining various aspects of citrus from its production to harvest. It looks at the challenges and approaches in stress tolerance improvements, increasing citrus crop productivity, and reducing postharvest losses. The book details taxonomy, genetic diversity, and metabolic and molecular responses in citrus crops, as well as abiotic and biotic stresses affecting citrus production. Featuring numerous full-color illustrations throughout, this book poses new harvesting techniques along with postharvest physiology of citrus fruits, devising strategies to prevent crop losses. Citrus Production: Technological Advancements and Adaptation to Changing Climate is an essential resource for researchers, academicians, and scientists looking to expand their knowledge of citrus, particularly horticulturists, food scientists, and botanists\"-- Provided by publisher.

Abiotic stresses are the primary sources of crop losses globally. The identification of key mechanisms deployed and established by plants in response to abiotic stresses is necessary for the maintenance of their growth and persistence. Recent discoveries have revealed that phytohormones or plant growth regulators (PGRs), mainly jasmonic acid (JA), have increased our knowledge of hormonal signaling of plants under stressful environments. Jasmonic acid is involved in various physiological and biochemical processes associated with plant growth and development as well as plant defense mechanism against wounding by pathogen and insect attacks. Recent findings suggest that JA can mediate the effect of abiotic stresses and help plants to acclimatize under unfavorable conditions. As a vital PGR, JA contributes in many signal transduction pathways, i.e., gene network, regulatory protein, signaling intermediates and enzymes, proteins, and other molecules that act to defend cells from the harmful effects of various environmental stresses. However, JA does not work as an independent regulator, but acts in a complex signaling pathway along other PGRs. Further, JA can protect and maintain the integrity of plant cells under several stresses by up-regulating the antioxidant defense. In this review, we have documented the biosynthesis and metabolism of JA and its protective role against different abiotic stresses. Further, JA-mediated antioxidant potential and its crosstalk with other PGRs have also been discussed.

Climate change is an invisible, silent killer with calamitous effects on living organisms. As the sessile organism, plants experience a diverse array of abiotic stresses during ontogenesis. The relentless climatic changes amplify the intensity and duration of stresses, making plants dwindle to survive. Plants convert 1–2% of consumed oxygen into reactive oxygen species (ROS), in particular, singlet oxygen (1O2), superoxide radical (O2•–), hydrogen peroxide (H2O2), hydroxyl radical (•OH), etc. as a byproduct of aerobic metabolism in different cell organelles such as chloroplast, mitochondria, etc. The regulatory network comprising enzymatic and non-enzymatic antioxidant systems tends to keep the magnitude of ROS within plant cells to a non-damaging level. However, under stress conditions, the production rate of ROS increases exponentially, exceeding the potential of antioxidant scavengers instigating oxidative burst, which affects biomolecules and disturbs cellular redox homeostasis. ROS are similar to a double-edged sword; and, when present below the threshold level, mediate redox signaling pathways that actuate plant growth, development, and acclimatization against stresses. The production of ROS in plant cells displays both detrimental and beneficial effects. However, exact pathways of ROS mediated stress alleviation are yet to be fully elucidated. Therefore, the review deposits information about the status of known sites of production, signaling mechanisms/pathways, effects, and management of ROS within plant cells under stress. In addition, the role played by advancement in modern techniques such as molecular priming, systems biology, phenomics, and crop modeling in preventing oxidative stress, as well as diverting ROS into signaling pathways has been canvassed.

The present study investigates the possible regulatory role of exogenous nitric oxide (NO) in mitigating oxidative stress in wheat seedlings exposed to arsenic (As). Seedlings were treated with NO donor (0.25 mM sodium nitroprusside, SNP) and As (0.25 and 0.5 mM Na 2 HAsO 4 ·7H 2 O) separately and/or in combination and grown for 72 h. Relative water content (RWC) and chlorophyll (chl) content were decreased by As treatment but proline (Pro) content was increased. The ascorbate (AsA) content was decreased significantly with increased As concentration. The imposition of As caused marked increase in the MDA and H 2 O 2 content. The amount of reduced glutathione (GSH) and glutathione disulfide (GSSG) significantly increased with an increase in the level of As (both 0.25 and 0.5 mM), while the GSH/GSSG ratio decreased at higher concentration (0.5 mM). The ascorbate peroxidase and glutathione S -transferase activities consistently increased with an increase in the As concentration, while glutathione reductase (GR) activities increased only at 0.25 mM. The monodehydroascorbate reductase (MDHAR) and catalase (CAT) activities were not changed upon exposure to As. The activities of dehydroascorbate reductase (DHAR) and glyoxalase I (Gly I) decreased at any levels of As, while glutathione peroxidase (GPX) and glyoxalase II (Gly II) activities decreased only upon 0.5 mM As. Exogenous NO alone had little influence on the non-enzymatic and enzymatic components compared to the control seedlings. These inhibitory effects of As were markedly recovered by supplementation with SNP; that is, the treatment with SNP increased the RWC, chl and Pro contents; AsA and GSH contents and the GSH/GSSG ratio as well as the activities of MDHAR, DHAR, GR, GPX, CAT, Gly I and Gly II in the seedlings subjected to As stress. These results suggest that the exogenous application of NO rendered the plants more tolerant to As-induced oxidative damage by enhancing their antioxidant defense and glyoxalase system.

Industrialization and inevitable mining have resulted in the release of some metals in environment, which have different uses on the one hand and also showed environmental toxicity. Lithium (Li) is one of them; however, its excess use in different fields or inappropriate disposal methods resulted in high Li accumulation in soil and groundwater. This subsequently is affecting our environment and more potentially our arable crop production system. In humans, Li has been extensively studied and causes numerous detrimental effects at different organ levels. Moreover, increases in Li in groundwater and food items, cases for mental disorders have been reported in different regions of the world. In plants, only a few studies have been reported about toxic effects of lithium in plants. Moreover, plant products (fruits, grains or other plant parts) could be a major source of Li toxicity in our food chain. Therefore, it is more imperative to understand how plants can be developed more tolerant to Li toxicity. In this short mini-review article, we primarily highlighted and speculated Li uptake, translocation and Li storage mechanism in plants. This article provides considerable information for breeders or environmentalist in identifying and developing Li hyperaccumulators plants and environment management.

In order to observe the possible regulatory role of selenium (Se) in relation to the changes in ascorbate (AsA) glutathione (GSH) levels and to the activities of antioxidant and glyoxalase pathway enzymes, rapeseed (Brassica napus) seedlings were grown in Petri dishes. A set of 10-day-old seedlings was pretreated with 25 μM Se (Sodium selenate) for 48 h. Two levels of drought stress (10% and 20% PEG) were imposed separately as well as on Se-pretreated seedlings, which were grown for another 48 h. Drought stress, at any level, caused a significant increase in GSH and glutathione disulfide (GSSG) content; however, the AsA content increased only under mild stress. The activity of ascorbate peroxidase (APX) was not affected by drought stress. The monodehydroascorbate reductase (MDHAR) and glutathione reductase (GR) activity increased only under mild stress (10% PEG). The activity of dehydroascorbate reductase (DHAR), glutathione S-transferase (GST), glutathione peroxidase (GPX), and glyoxalase I (Gly I) activity significantly increased under any level of drought stress, while catalase (CAT) and glyoxalase II (Gly II) activity decreased. A sharp increase in hydrogen peroxide (H2O2) and lipid peroxidation (MDA content) was induced by drought stress. On the other hand, Se-pretreated seedlings exposed to drought stress showed a rise in AsA and GSH content, maintained a high GSH/GSSG ratio, and evidenced increased activities of APX, DHAR, MDHAR, GR, GST, GPX, CAT, Gly I, and Gly II as compared with the drought-stressed plants without Se. These seedlings showed a concomitant decrease in GSSG content, H2O2, and the level of lipid peroxidation. The results indicate that the exogenous application of Se increased the tolerance of the plants to drought-induced oxidative damage by enhancing their antioxidant defense and methylglyoxal detoxification systems.

Unfavorable environmental conditions such as heat, cold, drought, metal/metalloid toxicity, and pathogens enhance production of intra-and inter-cellular levels of reactive oxygen species (ROS) in plants. ROS, acting as signaling molecules, activate signal transduction pathways in response to various stresses. Alternatively, ROS cause irreversible cellular damage due to lipid peroxidation, oxidation of protein, inactivation of enzymes, DNA damage, and interact with other vital constituents of plant cells through their strong oxidative properties, which drastically alter plant morphological structures, becoming disadvantageous for survival and productivity. Higher plants have complex defense systems to scavenge ROS. Being a central molecule of the defense system, gamma-aminobutyric acid (GABA) is ubiquitous from prokaryotes to eukaryotes cells. GABA helps mitigate ROS in plants and GABA shunt pathway plays a key role either as metabolites or endogenous signaling molecules in several regulatory mechanisms under stress conditions. The GABA transporters (GATs) being activated with the attachment of GABA under environmental stress stimuli facilitate high content of Ca2+ into the cytosol. Ca2+ combines with calmodulin (CaM) -binding domain that activates the glutamate decarboxylase (GAD) enzyme for the conversion of glutamate into GABA. This synchronized process regulates GABA shunt gene expressions under stress conditions and improves defense mechanisms in plants. This review highlights the regulatory aspects of GABA shunt pathway for ROS production as well as in the defense mechanism of plants.

Climate change has devastating effects on plant growth and yield. During ontogenesis, plants are subjected to a variety of abiotic stresses, including drought and salinity, affecting the crop loss (20–50%) and making them vulnerable in terms of survival. These stresses lead to the excessive production of reactive oxygen species (ROS) that damage nucleic acid, proteins, and lipids. Plant growth-promoting bacteria (PGPB) have remarkable capabilities in combating drought and salinity stress and improving plant growth, which enhances the crop productivity and contributes to food security. PGPB inoculation under abiotic stresses promotes plant growth through several modes of actions, such as the production of phytohormones, 1-aminocyclopropane-1-carboxylic acid deaminase, exopolysaccharide, siderophore, hydrogen cyanide, extracellular polymeric substances, volatile organic compounds, modulate antioxidants defense machinery, and abscisic acid, thereby preventing oxidative stress. These bacteria also provide osmotic balance; maintain ion homeostasis; and induce drought and salt-responsive genes, metabolic reprogramming, provide transcriptional changes in ion transporter genes, etc. Therefore, in this review, we summarize the effects of PGPB on drought and salinity stress to mitigate its detrimental effects. Furthermore, we also discuss the mechanistic insights of PGPB towards drought and salinity stress tolerance for sustainable agriculture.

Salinity and metal stress are significant abiotic factors that negatively influence plant growth and development. These factors lead to diminished agricultural yields on a global scale. Organic amendments have emerged as a potential solution for mitigating the adverse effects of salinity and metal stress on plants. When plants experience these stresses, they produce reactive oxygen species, which can impair protein synthesis and damage cellular membranes. Organic amendments, including biochar, vermicompost, green manure, and farmyard manure, have been shown to facilitate soil nitrogen uptake, an essential component for protein synthesis, and enhance various plant processes such as metabolism, protein accumulation, and antioxidant activities. Researchers have observed that the application of organic amendments improves plant stress tolerance, plant growth, and yield. They achieve this by altering the plant’s ionic balance, enhancing the photosynthetic machinery, boosting antioxidant systems, and reducing oxidative damage. The potential of organic amendments to deal effectively with high salinity and metal concentrations in the soil is gaining increased attention and is becoming an increasingly popular practice in the field of agriculture. This review aims to provide insights into methods for treating soils contaminated with salinity and heavy metals by manipulating their bioavailability through the use of various soil amendments.

Oxygen (O2) is the most crucial substrate for numerous biochemical processes in plants. Its deprivation is a critical factor that affects plant growth and may lead to death if it lasts for a long time. However, various biotic and abiotic factors cause O2 deprivation, leading to hypoxia and anoxia in plant tissues. To survive under hypoxia and/or anoxia, plants deploy various mechanisms such as fermentation paths, reactive oxygen species (ROS), reactive nitrogen species (RNS), antioxidant enzymes, aerenchyma, and adventitious root formation, while nitrate (NO3−), nitrite (NO2−), and nitric oxide (NO) have shown numerous beneficial roles through modulating these mechanisms. Therefore, in this review, we highlight the role of reductive pathways of NO formation which lessen the deleterious effects of oxidative damages and increase the adaptation capacity of plants during hypoxia and anoxia. Meanwhile, the overproduction of NO through reductive pathways during hypoxia and anoxia leads to cellular dysfunction and cell death. Thus, its scavenging or inhibition is equally important for plant survival. As plants are also reported to produce a potent greenhouse gas nitrous oxide (N2O) when supplied with NO3− and NO2−, resembling bacterial denitrification, its role during hypoxia and anoxia tolerance is discussed here. We point out that NO reduction to N2O along with the phytoglobin-NO cycle could be the most important NO-scavenging mechanism that would reduce nitro-oxidative stress, thus enhancing plants’ survival during O2-limited conditions. Hence, understanding the molecular mechanisms involved in reducing NO toxicity would not only provide insight into its role in plant physiology, but also address the uncertainties seen in the global N2O budget.