The environmental stress is a major area of scientific concern because it constraints plant as well as crop productivity. This situation has been further worsened by anthropogenic activities. ...Therefore, there is a much scientific saddle on researchers to enhance crop productivity under environmental stress in order to cope with the increasing food demands. The abiotic stresses such as salinity, drought, cold, and heat negatively influence the survival, biomass production and yield of staple food crops. According to an estimate of FAO, over 6 % of the world’s land is affected by salinity. Thus, salinity stress appears to be a major constraint to plant and crop productivity. Here, we review our understanding of salinity impact on various aspects of plant metabolism and its tolerance strategies in plants.
Heavy metal contamination of soil and water causing toxicity/stress has become one important constraint to crop productivity and quality. This situation has further worsened by the increasing ...population growth and inherent food demand. It has been reported in several studies that counterbalancing toxicity due to heavy metal requires complex mechanisms at molecular, biochemical, physiological, cellular, tissue, and whole plant level, which might manifest in terms of improved crop productivity. Recent advances in various disciplines of biological sciences such as metabolomics, transcriptomics, proteomics, etc., have assisted in the characterization of metabolites, transcription factors, and stress-inducible proteins involved in heavy metal tolerance, which in turn can be utilized for generating heavy metal-tolerant crops. This review summarizes various tolerance strategies of plants under heavy metal toxicity covering the role of metabolites (metabolomics), trace elements (ionomics), transcription factors (transcriptomics), various stress-inducible proteins (proteomics) as well as the role of plant hormones. We also provide a glance of some strategies adopted by metal-accumulating plants, also known as "metallophytes."
Abiotic stresses collectively are responsible for crop losses worldwide. Among various abiotic stresses, drought and salinity are the most destructive. Different strategies have been adopted for the ...management of these stresses. Being complex traits, conventional breeding approaches have shown less success in improving salinity and drought stress tolerance. Roles of compatible solutes in salinity and drought stress tolerance have been studied extensively. At physiological level, osmotic adjustment is an adaptive mechanism involved in drought and/or salinity tolerance and permits the maintenance of turgor pressure under stress conditions. Increasing evidences from series of in vivo and in vitro studies involving physiological, biochemical, genetic, and molecular approaches strongly suggest that osmolytes such as ammonium compounds (polyamines, glycinebetaine, b-alanine betaine, dimethyl-sulfonio propionate and choline-O-sulfate), sugars and sugar alcohols (fructan, trehalose, mannitol, D-ononitol and sorbitol) and amino acids (proline and ectoine) perform important function in adjustment of plants against salinity and drought stresses. Thus, aim of this review is to expose how to osmoprotectants detoxify adverse effect of reactive oxygen species and alleviate drought and salinity stresses. An understanding of the relationship between these two sets of parameters is needed to develop measures for mitigating the damaging impacts of salinity and drought stresses.
Understanding the adverse impact of nanoparticles in crop plants has emerged as one of the most interesting fields of plant research. Therefore, this study has been conducted to investigate the ...impact of silver nanoparticles (AgNps) on Pisium sativum seedlings. Besides this, we have also tested whether nitric oxide (NO) is capable of reducing toxicity of AgNps or not. NO has been found as one of the most fascinating molecules, capable of enhancing plant tolerance to different environmental stresses. The results of the present study showed that AgNps treatments (1000 μM and 3000 μM) significantly declined growth parameters, photosynthetic pigments and chlorophyll fluorescence of pea seedlings, which could be correlated with increased accumulation of Ag in root and shoot of pea seedlings. In contrast, addition of SNP (100 μM; a donor of NO) successfully ameliorated AgNp-induced adverse effects on these parameters as it reduced accumulation of Ag and repaired damaged tissues. Levels of oxidative stress markers (SOR, H2O2 and MDA) were enhanced while their levels significantly reduced under SNP addition. AgNps (1000 μM and 3000 μM) significantly stimulated the activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) while inhibited activities of glutathione reductase (GR) and dehydroascorbate reductase (DHAR). AgNps also considerably declined the total ascorbate and glutathione contents and severely damaged leaf and root anatomical structures. On the other hand, addition of SNP further increased the level of SOD, APX, GR and DHAR and significantly increased the decreased levels of total ascorbate and glutathione contents, and repaired anatomical structures. In conclusion, this study suggests that AgNps treatments adversely decreased growth, pigments and photosynthesis due to enhanced level of Ag and oxidative stress. However, SNP addition successfully ameliorates adverse impact of AgNps on pea seedlings by regulating the Ag uptake, antioxidant system, oxidative stress and anatomical structures of root and shoot.
•AgNps adversely affects growth and photosynthesis in Pisum sativum.•It happens because of enhanced accumulation of AgNps and ROS.•NO (SNP) protects pea seedlings against AgNps by regulating accumulation of Ag and ROS, and antioxidants.
Cyanobacteria and algae having complex photosynthetic systems can channelize absorbed solar energy into other forms of energy for production of food and metabolites. In addition, they are promising ...biocatalysts and can be used in the field of "white biotechnology" for enhancing the sustainable production of food, metabolites, and green energy sources such as biodiesel. In this review, an endeavor has been made to uncover the significance of various metabolites like phenolics, phytoene/terpenoids, phytols, sterols, free fatty acids, photoprotective compounds (MAAs, scytonemin, carotenoids, polysaccharides, halogenated compounds, etc.), phytohormones, cyanotoxins, biocides (algaecides, herbicides, and insecticides) etc. Apart from this, the importance of these metabolites as antibiotics, immunosuppressant, anticancer, antiviral, anti-inflammatory agent has also been discussed. Metabolites obtained from cyanobacteria and algae have several biotechnological, industrial, pharmaceutical, and cosmetic uses which have also been discussed in this review along with the emerging technology of their harvesting for enhancing the production of compounds like bioethanol, biofuel etc. at commercial level. In later sections, we have discussed genetically modified organisms and metabolite production from them. We have also briefly discussed the concept of bioprocessing highlighting the functioning of companies engaged in metabolites production as well as their cost effectiveness and challenges that are being addressed by these companies.
Reactive oxygen species (ROS) are generated inevitably in the redox reactions of plants, including respiration and photosynthesis. In earlier studies, ROS were considered as toxic by-products of ...aerobic pathways of the metabolism. But in recent years, concept about ROS has changed because they also participate in developmental processes of plants by acting as signaling molecules. In plants, ROS regulate many developmental processes such as cell proliferation and differentiation, programmed cell death, seed germination, gravitropism, root hair growth and pollen tube development, senescence, etc. Despite much progress, a comprehensive update of advances in the understanding of the mechanisms evoked by ROS that mediate in cell proliferation and development are fragmentry and the matter of ROS perception and the signaling cascade remains open. Therefore, keeping in view the above facts, an attempt has been made in this article to summarize the recent findings regarding updates made in the regulatory action of ROS at various plant developmental stages, which are still not well-known.
•NO and ROS regulate formation of NARs and PRBA under AsV stress.•Redox couple of ascorbate and cell cycle dynamics also play a role in the formation of NARs and PRBA.•NARs and PRBA are an ...arrangement for diluting AsV.
Nitric oxide (NO) and reactive oxygen species (ROS) are important signaling molecules regulating development of plants. However under metal stress, in developmental processes of plants their implications are not largely known. Therefore, in the present study, role of NO and ROS crosstalk in the regulation of formation of new adventitious roots (NARs) and primary root biomass accumulation (PRBA) has been investigated in rice seedlings under arsenate (AsV) stress. Addition of sodium nitroprusside (SNP, a donor of NO) induced formation of NARs, increased PRBA, and maintained the redox status of ascorbate and cell cycle dynamics. However, addition of NG-nitro-l-arginine methyl ester (L-NAME, an inhibitor of nitric oxide synthase) and 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO, a NO scavenger) either in presence of SNP or in its absence blocked formation of NARs and reduced PRBA. Further, to decipher crosstalk of NO and ROS, we used diphenylene iodonium (DPI, an inhibitor of NADPH oxidase), and even in presence of SNP it blocked formation of NARs which indicate that ROS are also essential for formation of NARs. Further a connection of NO-ROS signaling with the redox status of ascorbate and the cell cycle dynamics, governing formation of NARs and PRBA in rice seedlings under AsV stress is discussed.
Reactive oxygen species (ROS), a by-product of aerobic metabolism were initially studied in context to their damaging effect but recent decades witnessed significant advancements in understanding the ...role of ROS as signaling molecules. Contrary to earlier views, it is becoming evident that ROS production is not necessarily a symptom of cellular dysfunction but it might represent a necessary signal in adjusting the cellular machinery according to the altered conditions. Stomatal movement is controlled by multifaceted signaling network in response to endogenous and environmental signals. Furthermore, the stomatal aperture is regulated by a coordinated action of signaling proteins, ROS-generating enzymes, and downstream executors like transporters, ion pumps, plasma membrane channels, which control the turgor pressure of the guard cell. The earliest hallmarks of stomatal closure are ROS accumulation in the apoplast and chloroplasts and thereafter, there is a successive increase in cytoplasmic Ca2+ level which rules the multiple kinases activity that in turn regulates the activity of ROS-generating enzymes and various ion channels. In addition, ROS also regulate the action of multiple proteins directly by oxidative post translational modifications to adjust guard cell signaling. Notwithstanding, an active progress has been made with ROS signaling mechanism but the regulatory action for ROS signaling processes in stomatal movement is still fragmentary. Therefore, keeping in view the above facts, in this mini review the basic concepts and role of ROS signaling in the stomatal movement have been presented comprehensively along with recent highlights.
Abiotic stress is considered as the main culprit for reduction of global food production. Recent studies have reported GABA as a major regulator of abiotic stress and thus opening new avenues in ...research on emerging roles of GABA in abiotic stress acclimation in plants.
Diabetic Retinopathy (DR) is an emerging public health issue, leading to severe visual impairment or blindness. Early identification and prompt treatment play a key role in achieving good visual ...outcomes. The objective of the study was to estimate the effectiveness of SCREEN package on improving referral compliance from peripheral centres to a tertiary eye centre in Nepal.
In this facility-based cluster-randomized trial, ten out of 19 referring centres of the tertiary eye care centre in Lumbini zone, Nepal were randomized into intervention and control groups. A SCREEN packagewereprovided as intervention for DR patients who require advanced treatment in the tertiary centres and was compared with the current practice of the control arm, where structured counselling and follow-up mechanism are absent. Compliance was estimated by a weekly follow-up between the referring centre and the referred hospital.
We recruited 302 participantsof whom 153 were in the intervention arm. The mean age of the participants was 57.8 years (Standard deviation SD±11.7 years). With implementation of SCREEN package71.2% (n=109) in the intervention group and 42.9% (n=64) in the control group were compliant till three months of follow-up (Difference 28.3%, 95% CI: 17.6- 39.0, p<0.05). Compliance was 43% (n=66) with counselling alone, and 66% (n=103) with first telephonic follow-up in the intervention arm. The mean duration to reach the referral centre was 14.7 days (SD± 9.4 days) and 18.2 days (SD± 9.1 days) in the intervention and the control arm, respectively (Difference 3.5 days, 95% CI: 0.7 to 6.4 days).
Counselling& follow-up to patients is the key factor to improve the utilization of the health services by patients with DR. Health systems must be strengthened by optimizing the existing referral structure in Nepal.
ClinicalTrials.gov Protocol Registration and Results System, ClinicalTrials.gov Identifier: NCT04834648 , 08/04/2021.
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