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Molecular Plant Nov 2017The apoplast is an interconnected compartment with a thin water-film that alkalinizes under stress. This systemic pH increase may be a secondary effect without... (Review)
Review
The apoplast is an interconnected compartment with a thin water-film that alkalinizes under stress. This systemic pH increase may be a secondary effect without functional implications, arising from ion movements or proton-pump regulations. On the other hand, there are increasing indications that it is part of a mechanism to withstand stress. Regardless of this controversy, alkalinization of the apoplast has received little attention. The apoplastic pH (pH) increases not only during plant-pathogen interactions but also in response to salinity or drought. Not much is known about the mechanisms that cause the leaf apoplast to alkalinize, nor whether, and if so, how functional impact is conveyed. Controversial explanations have been given, and the unusual complexity of pH regulation is considered as the primary reason behind this lack of knowledge. A gathering of scattered information revealed that changes in pH convey functionality by regulating stomatal aperture via the effects exerted on abscisic acid. Moreover, apoplastic alkalinization may regulate growth under stress, whereas this needs to be verified. In this review, a comprehensive survey about several physiological mechanisms that alkalize the apoplast under stress is given, and the suitability of apoplastic alkalinization as transducing element for the transmission of sensory information is discussed.
Topics: Abscisic Acid; Hydrogen-Ion Concentration; Plant Proteins; Plant Stomata
PubMed: 28987886
DOI: 10.1016/j.molp.2017.09.018 -
Scientific Reports Jul 2023Nitrogen (N) and phosphorus (P) are important nutrients for plant growth and development. Soil alkalization is one of the main obstacles limiting the sustainable...
Nitrogen (N) and phosphorus (P) are important nutrients for plant growth and development. Soil alkalization is one of the main obstacles limiting the sustainable development of agriculture. Northern Ningxia is located in the arid and semi-arid region, with serious soil alkalinization. Alfalfa has the advantages of strong saline-alkali tolerance, high yield, high quality, and wide adaptability. It is an important forage for the comprehensive improvement and rational utilization of saline-alkali land and has great significance for solving land resource shortages, improving the ecological environment, and ensuring food security. It is important to study soil organic carbon (SOC), total N (TN), total P (TP), and stoichiometry of the rhizosphere and non-rhizosphere of alfalfa in alkaline soils. Therefore, N and P were added to the alkaline alfalfa field in the Yinchuan Plain of Hetao Basin in our experiment. Six treatments were set up, i.e., N-free (WN), medium N (MN) for 90 kg/hm, high N (HN) for 180 kg/hm, P-free (WP), medium P (MP) for 135 kg/hm, and high P (HP) for 270 kg/hm. The results are as follows: The N addition promotes SOC and TN but inhibits TP, and P addition promotes SOC and TP but inhibits TN of three soil layers. The N addition decreases C/N but increases C/P and N/P, while the P addition increases C/N but decreases C/P and N/P of three soil layers. The SOC, TN, TP, C/N, C/P, and N/P under HN and HP treatment reach the significance level (P < 0.05). Appropriate additions of N and P can improve rhizosphere and non-rhizosphere nutrients and stoichiometric structure, facilitating absorption and utilization by alfalfa and improve the production potential of alfalfa in alkaline soil.
Topics: Soil; Medicago sativa; Carbon; Nitrogen; Nutrients; Alkalies; China
PubMed: 37495627
DOI: 10.1038/s41598-023-39030-8 -
International Journal of Environmental... Sep 2022The high salt-alkalinity of bauxite residue (BR) hinders plant growth and revegetation of bauxite residue disposal areas (BRDA), which cause serious potential...
The high salt-alkalinity of bauxite residue (BR) hinders plant growth and revegetation of bauxite residue disposal areas (BRDA), which cause serious potential environmental and ecological risks. Bioneutralization is a promising method for improving the properties of BR and plant colonization. In the present study, a strong saline-alkali tolerant bacteria (ZH-1) was isolated from aged BR and identified as sp. The medium of ZH-1 was optimized by orthogonal tests, and ZH-1 could decrease the medium pH from 11.8 to 6.01 (agitated culture) and 6.48 (static culture) by secretion of citric acid, oxalic acid and tartaric acid. With the inoculation of ZH-1, the pH of BR decreased from 11.6 to 8.76, and the water-soluble salt in BR increased by 68.11%. ZH-1 also changed the aggregate size distribution of BR, the mechanical-stable aggregates and water-stable aggregates increased by 18.76% and 10.83%, respectively. At the same time, the stability of the aggregates obviously increased and the destruction rate decreased from 94.37% to 73.46%. In addition, the microbial biomass carbon increased from 425 to 2794 mg/kg with the inoculation of ZH-1. Bacterial community analysis revealed that Clostridia, Bacilli, Gammaproteobacteria, Betaproteobacteria and Alphaproteobacteria were the main classes in the naturalized BR, and the inoculation of ZH-1 increased the diversity of bacteria in the BR. Overall, ZH-1 has great potential for neutralization and improvement the properties of BR and may be greatly beneficial for the revegetation of BRDA.
Topics: Alkalies; Aluminum Oxide; Bacteria; Carbon; Oxalic Acid; Plants; Soil; Water
PubMed: 36141868
DOI: 10.3390/ijerph191811590 -
Biochimica Et Biophysica Acta Nov 2005The capacity of bacteria to survive and grow at alkaline pH values is of widespread importance in the epidemiology of pathogenic bacteria, in remediation and industrial... (Review)
Review
The capacity of bacteria to survive and grow at alkaline pH values is of widespread importance in the epidemiology of pathogenic bacteria, in remediation and industrial settings, as well as in marine, plant-associated and extremely alkaline ecological niches. Alkali-tolerance and alkaliphily, in turn, strongly depend upon mechanisms for alkaline pH homeostasis, as shown in pH shift experiments and growth experiments in chemostats at different external pH values. Transcriptome and proteome analyses have recently complemented physiological and genetic studies, revealing numerous adaptations that contribute to alkaline pH homeostasis. These include elevated levels of transporters and enzymes that promote proton capture and retention (e.g., the ATP synthase and monovalent cation/proton antiporters), metabolic changes that lead to increased acid production, and changes in the cell surface layers that contribute to cytoplasmic proton retention. Targeted studies over the past decade have followed up the long-recognized importance of monovalent cations in active pH homeostasis. These studies show the centrality of monovalent cation/proton antiporters in this process while microbial genomics provides information about the constellation of such antiporters in individual strains. A comprehensive phylogenetic analysis of both eukaryotic and prokaryotic genome databases has identified orthologs from bacteria to humans that allow better understanding of the specific functions and physiological roles of the antiporters. Detailed information about the properties of multiple antiporters in individual strains is starting to explain how specific monovalent cation/proton antiporters play dominant roles in alkaline pH homeostasis in cells that have several additional antiporters catalyzing ostensibly similar reactions. New insights into the pH-dependent Na(+)/H(+) antiporter NhaA that plays an important role in Escherichia coli have recently emerged from the determination of the structure of NhaA. This review highlights the approaches, major findings and unresolved problems in alkaline pH homeostasis, focusing on the small number of well-characterized alkali-tolerant and extremely alkaliphilic bacteria.
Topics: Alkalies; Escherichia coli; Escherichia coli Proteins; Gene Expression Regulation, Bacterial; Genes, Bacterial; Homeostasis; Hydrogen-Ion Concentration; Ion Transport; Sodium-Hydrogen Exchangers
PubMed: 16277975
DOI: 10.1016/j.bbamem.2005.09.010 -
International Journal of Molecular... Dec 2022Saline-alkali stress is a widespread adversity that severely affects plant growth and productivity. Saline-alkaline soils are characterized by high salt content and high... (Review)
Review
Saline-alkali stress is a widespread adversity that severely affects plant growth and productivity. Saline-alkaline soils are characterized by high salt content and high pH values, which simultaneously cause combined damage from osmotic stress, ionic toxicity, high pH and HCO/CO stress. In recent years, many determinants of salt tolerance have been identified and their regulatory mechanisms are fairly well understood. However, the mechanism by which plants respond to comprehensive saline-alkali stress remains largely unknown. This review summarizes recent advances in the physiological, biochemical and molecular mechanisms of plants tolerance to salinity or salt- alkali stress. Focused on the progress made in elucidating the regulation mechanisms adopted by plants in response to saline-alkali stress and present some new views on the understanding of plants in the face of comprehensive stress. Plants generally promote saline-alkali tolerance by maintaining pH and Na homeostasis, while the plants responding to HCO/CO stress are not exactly the same as high pH stress. We proposed that pH-tolerant or sensitive plants have evolved distinct mechanisms to adapt to saline-alkaline stress. Finally, we highlight the areas that require further research to reveal the new components of saline-alkali tolerance in plants and present the current and potential application of key determinants in breed improvement and molecular breeding.
Topics: Alkalies; Salt Tolerance; Plant Breeding; Plants; Salt Stress; Saline Solution
PubMed: 36555693
DOI: 10.3390/ijms232416048 -
Comprehensive Reviews in Food Science... Jul 2020Alkalization, also known as "Dutching," is an optional, but very useful, step taken in the production chain of cocoa to darken its color, modify its taste, and increase... (Review)
Review
Alkalization, also known as "Dutching," is an optional, but very useful, step taken in the production chain of cocoa to darken its color, modify its taste, and increase natural cocoa solubility. Over the years, various attempts have been made to design new and more effective alkalization methods. Moreover, different authors have attempted to elucidate the impact of alkalization on the physicochemical, nutritional, functional, microbiological, and sensory characteristics of alkalized cocoa. The aim of this review is to provide a clear guide about not only the conditions that can be applied to alkalize cocoa, but also the reported effects of alkalization on the nutritional, functional, microbiological, and sensory characteristics of cocoa. The first part of this review describes different cocoa alkalization systems and how they can be tuned to induce specific changes in cocoa properties. The second part is a holistic analysis of the effects of the alkalization process on different cocoa features, performed by emphasizing the biochemistry behind all these transformations.
Topics: Alkalies; Cacao; Color; Food Handling; Nutritive Value; Taste
PubMed: 33337074
DOI: 10.1111/1541-4337.12581 -
Annales de Biologie Clinique 2007Cystinuria is an autosomal recessive disorder characterized by an impaired transport of cystine and dibasic aminoacids, lysine, arginine and ornithine in the proximal... (Review)
Review
Cystinuria is an autosomal recessive disorder characterized by an impaired transport of cystine and dibasic aminoacids, lysine, arginine and ornithine in the proximal renal tubule and in the epithelial cells of the gastrointestinal tract. Recurrent cystine nephrolithiasis is the main clinical feature. Mutations in SLC3A1 and/or SLC7A9 genes, which are encoding respectively the rBAT and the b(0,+)AT proteins of the amino acid transport system, are responsible of this disorder thus inducing a high dibasic amino acid excretion. Diagnostic is based on stone analysis by infrared spectroscopy or microscopic examination of urine which may reveal typical cystine crystals. Quantitative cystine excretion, which may be assessed by aminoacid chromatography, is higher in cystinic patients. Molecular approach can identify mutations which are responsible of this pathology. Medical treatment is mainly based on hydratation and urine alkalinisation, with the addition of thiol derivative only in refractory cases. Follow-up based on pH and specific gravity determination in urine samples and cystine crystal volume measurement are used to optimally monitor the medical treatment of cystinuric patients. Even with medical management, long-term outcome is poor due to insufficient efficacy and low patient compliance. Many patients suffer from renal insufficiency as a result of recurrent stone formation and repeated surgical procedures.
Topics: Alkalies; Cystinuria; Fluid Therapy; Follow-Up Studies; Humans; Hydrogen-Ion Concentration; Patient Care Planning; Specific Gravity
PubMed: 17913667
DOI: No ID Found -
International Journal of Molecular... Nov 2023Ensuring food security for the global population is a ceaseless and critical issue. However, high-salinity and high-alkalinity levels can harm agricultural yields... (Review)
Review
Ensuring food security for the global population is a ceaseless and critical issue. However, high-salinity and high-alkalinity levels can harm agricultural yields throughout large areas, even in largely agricultural countries, such as China. Various physical and chemical treatments have been employed in different locations to mitigate high salinity and alkalinity but their effects have been minimal. Numerous researchers have recently focused on developing effective and environmentally friendly biological treatments. Endophytes, which are naturally occurring and abundant in plants, retain many of the same characteristics of plants owing to their simultaneous evolution. Therefore, extraction of endophytes from salt-tolerant plants for managing plant growth in saline-alkali soils has become an important research topic. This extraction indicates that the soil environment can be fundamentally improved, and the signaling pathways of plants can be altered to increase their defense capacity, and can even be inherited to ensure lasting efficacy. This study discusses the direct and indirect means by which plant endophytes mitigate the effects of plant salinity stress that have been observed in recent years.
Topics: Endophytes; Salinity; Alkalies; Salt Tolerance; Salt-Tolerant Plants
PubMed: 38069239
DOI: 10.3390/ijms242316917 -
MBio Dec 2021Trypanosoma cruzi, the agent of Chagas disease, accumulates polyphosphate (polyP) and Ca inside acidocalcisomes. The alkalinization of this organelle stimulates polyP...
Trypanosoma cruzi, the agent of Chagas disease, accumulates polyphosphate (polyP) and Ca inside acidocalcisomes. The alkalinization of this organelle stimulates polyP hydrolysis and Ca release. Here, we report that histidine ammonia lyase (HAL), an enzyme that catalyzes histidine deamination with production of ammonia (NH) and urocanate, is responsible for acidocalcisome alkalinization. Histidine addition to live parasites expressing HAL fused to the pH-sensitive emission biosensor green fluorescent protein (GFP) variant pHluorin induced alkalinization of acidocalcisomes. PolyP decreased HAL activity of epimastigote lysates or the recombinant protein but did not cause its polyphosphorylation, as determined by the lack of HAL electrophoretic shift on NuPAGE gels using both and conditions. We demonstrate that HAL binds strongly to polyP and localizes to the acidocalcisomes and cytosol of the parasite. Four lysine residues localized in the HAL C-terminal region are instrumental for its polyP binding, its inhibition by polyP, its function inside acidocalcisomes, and parasite survival under starvation conditions. Expression of HAL in yeast deficient in polyP degradation decreased cell fitness. This effect was enhanced by histidine and decreased when the lysine-rich C-terminal region was deleted. In conclusion, this study highlights a mechanism for stimulation of acidocalcisome alkalinization linked to amino acid metabolism. Trypanosoma cruzi is the etiologic agent of Chagas disease and is characterized by the presence of acidocalcisomes, organelles rich in phosphate and calcium. Release of these molecules, which are necessary for growth and cell signaling, is induced by alkalinization, but a physiological mechanism for acidocalcisome alkalinization was unknown. In this work, we demonstrate that a histidine ammonia lyase localizes to acidocalcisomes and is responsible for their alkalinization.
Topics: Alkalies; Amino Acid Motifs; Calcium; Chagas Disease; Histidine; Histidine Ammonia-Lyase; Humans; Organelles; Polyphosphates; Protozoan Proteins; Trypanosoma cruzi
PubMed: 34724827
DOI: 10.1128/mBio.01981-21 -
BMC Microbiology Sep 2021Saline and alkaline stresses damages the health of soil systems. Meanwhile, little is known about how saline or alkaline stress affects soil nitrifier and denitrifier...
BACKGROUND
Saline and alkaline stresses damages the health of soil systems. Meanwhile, little is known about how saline or alkaline stress affects soil nitrifier and denitrifier communities. Therefore, we compared the responses of gene-based nitrifier and denitrifier communities to chloride (CS), sulfate (SS), and alkaline (AS) stresses with those in a no-stress control (CK) in pots with a calcareous desert soil.
RESULTS
Compared with CK, saline and alkaline stress decreased potential nitrification rate (PNR) and NO-N; increased pH, salinity, water content, and NH-N; and decreased copy numbers of amoA-AOA and amoA-AOB genes but increased those of denitrifier nirS and nosZ genes. Copies of nirK increased in SS and AS but decreased in CS. There were more copies of amoA-AOB than of amoA-AOA and of nirS than of nirK or nosZ. Compared with CK, SS and AS decreased operational taxonomic units (OTUs) of amoA-AOB but increased those of nirS and nosZ, whereas CS decreased nirK OTUs but increased those of nosZ. The numbers of OTUs and amoA-AOB genes were greater than those of amoA-AOA. There were positive linear relations between PNR and amoA-AOA and amoA-AOB copies. Compared with CK, the Chao 1 index of amoA-AOA and amoA-AOB decreased in AS, that of nirK increased in CS and SS, but that of nirS and nosZ increased in all treatments. The Shannon index of amoA-AOB decreased but that of nirS increased in CS and SS, whereas the index of nirK decreased in all treatments. Saline and alkaline stress greatly affected the structure of nitrifier and denitrifier communities and decreased potential biomarkers of nirS-type; however, AS increased those of nirK- and nosZ-type, and SS decreased those of nosZ-type. Soil water content, pH, and salinity were important in shaping amoA-AOA and denitrifier communities, whereas soil water and pH were important to amoA-AOB communities.
CONCLUSION
These results indicate that the nitrifier and denitrifier communities respond to saline and alkaline stresses conditions. Communities of amoA-AOA and amoA-AOB contribute to nitrification in alluvial gray desert soil, and those of nirS are more important in denitrification than those of nirK or nosZ.
Topics: Alkalies; Archaea; Desert Climate; Microbiota; Nitrification; Salt Stress; Soil; Soil Microbiology
PubMed: 34521348
DOI: 10.1186/s12866-021-02313-z