scholarly journals Transport of organic anions in root cells and its role in cell signaling in higher plants

2021 ◽  
Vol 65 (3) ◽  
pp. 320-329
Author(s):  
V. V. Demidchik ◽  
P. V. Hryvusevich ◽  
M. A. Vaitsiakhovich ◽  
J. V. Talkachova ◽  
A. V. Kulinkovich ◽  
...  
Keyword(s):  
Higher Plants ◽  
Organic Anion ◽  
Plant Stress ◽  
Anion Channel ◽  
Organic Anions ◽  
Anion Channels ◽  
Patch Clamp Technique ◽  
Long Distance ◽  
Root Cells ◽  
Rapid Activation

The organic anion balance is critical for metabolic, bioenergetic, and electrochemical processes in plant cells, controlling the quality and quantity of yield and plant stress resistance. Nevertheless, the redistribution and membrane transport of these substances in plant tissues have not been investigated in detail. The mechanism of passive anion efflux from a plant cell through the ion channels has not been established so far. Here, using the patch-clamp technique, we have characterized the ion channel-mediated conductances of ascorbate, malate, gluconate, citrate, fumarate, and pronionate in the root cells of Arabidopsis thaliana, Triticum aestivum, and Helianthus annuus. These conductances showed high permeability to ascorbate, malate, and citrate, as well as low permeability to fumarate, propionate, and gluconate. Anion channel conductances of root cells showed rapid activation kinetics and low potential dependence. They were also inhibited by 9-anthracenecarboxylic acid, suggesting that they belong to the ALMT family of anion channels found only in higher plants. Aequorin chemilu minometry was used to test the effect of organic anions on the Ca2+ signaling in root cells. Among four organic anions tested, only ascorbate induced a significant increase in the cytosolic Ca2+ activity at physiological levels (1 and 10 mM). This effect may underlie the previously unknown functions of exogenous ascorbate related to short- and long-distance signaling in higher plants.

scholarly journals Chloride as a Beneficial Macronutrient in Higher Plants: New Roles and Regulation

2019 ◽  
Vol 20 (19) ◽  
pp. 4686 ◽  
Author(s):  
José M. Colmenero-Flores ◽  
Juan D. Franco-Navarro ◽  
Paloma Cubero-Font ◽  
Procopio Peinado-Torrubia ◽  
Miguel A. Rosales
Keyword(s):  
Higher Plants ◽  
Optimal Growth ◽  
Long Distance ◽  
Root Cells ◽  
Long Distance Transport ◽  
New Genes ◽  
Genes Encoding ◽  
Cell Turgor ◽  
Use Efficiency ◽  
High Concentrations

Chloride (Cl−) has traditionally been considered a micronutrient largely excluded by plants due to its ubiquity and abundance in nature, its antagonism with nitrate (NO3−), and its toxicity when accumulated at high concentrations. In recent years, there has been a paradigm shift in this regard since Cl− has gone from being considered a harmful ion, accidentally absorbed through NO3− transporters, to being considered a beneficial macronutrient whose transport is finely regulated by plants. As a beneficial macronutrient, Cl− determines increased fresh and dry biomass, greater leaf expansion, increased elongation of leaf and root cells, improved water relations, higher mesophyll diffusion to CO2, and better water- and nitrogen-use efficiency. While optimal growth of plants requires the synchronic supply of both Cl− and NO3− molecules, the NO3−/Cl− plant selectivity varies between species and varieties, and in the same plant it can be modified by environmental cues such as water deficit or salinity. Recently, new genes encoding transporters mediating Cl− influx (ZmNPF6.4 and ZmNPF6.6), Cl− efflux (AtSLAH3 and AtSLAH1), and Cl− compartmentalization (AtDTX33, AtDTX35, AtALMT4, and GsCLC2) have been identified and characterized. These transporters have proven to be highly relevant for nutrition, long-distance transport and compartmentalization of Cl−, as well as for cell turgor regulation and stress tolerance in plants.

scholarly journals A Theoretical Analysis of Relations between Pressure Changes along Xylem Vessels and Propagation of Variation Potential in Higher Plants

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 372
Author(s):  
Ekaterina Sukhova ◽  
Elena Akinchits ◽  
Sergey V. Gudkov ◽  
Roman Y. Pishchalnikov ◽  
Vladimir Vodeneev ◽  
...  
Keyword(s):  
Higher Plants ◽  
Initial Point ◽  
Electrical Signal ◽  
Terminal Point ◽  
Hydraulic Pressure ◽  
Long Distance ◽  
Variation Potential ◽  
Damaged Zone ◽  
Pressure Dynamics ◽  
The Impact

Variation potential (VP) is an important long-distance electrical signal in higher plants that is induced by local damages, influences numerous physiological processes, and participates in plant adaptation to stressors. The transmission of increased hydraulic pressure through xylem vessels is the probable mechanism of VP propagation in plants; however, the rates of the pressure transmission and VP propagation can strongly vary. We analyzed this problem on the basis of a simple mathematical model of the pressure distribution along a xylem vessel, which was approximated by a tube with a pressure gradient. It is assumed that the VP is initiated if the integral over pressure is more than a threshold one, taking into account that the pressure is transiently increased in the initial point of the tube and is kept constant in the terminal point. It was shown that this simple model can well describe the parameters of VP propagation in higher plants, including the increase in time before VP initiation and the decrease in the rate of VP propagation with an increase in the distance from the zone of damage. Considering three types of the pressure dynamics, our model predicts that the velocity of VP propagation can be stimulated by an increase in the length of a plant shoot and also depends on pressure dynamics in the damaged zone. Our results theoretically support the hypothesis about the impact of pressure variations in xylem vessels on VP propagation.

scholarly journals OsNAC45 is Involved in ABA Response and Salt Tolerance in Rice

Rice ◽  
2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Xiang Zhang ◽  
Yan Long ◽  
Jingjing Huang ◽  
Jixing Xia
Keyword(s):  
Transcription Factors ◽  
Salt Stress ◽  
Salt Tolerance ◽  
Stress Responses ◽  
Crop Yields ◽  
Plant Stress ◽  
Root Cells ◽  
Nac Transcription Factors ◽  
Rice Plants ◽  
Plant Stress Responses

Abstract Background Salt stress threatens crop yields all over the world. Many NAC transcription factors have been reported to be involved in different abiotic stress responses, but it remains unclear how loss of these transcription factors alters the transcriptomes of plants. Previous reports have demonstrated that overexpression of OsNAC45 enhances salt and drought tolerance in rice, and that OsNAC45 may regulate the expression of two specific genes, OsPM1 and OsLEA3–1. Results Here, we found that ABA repressed, and NaCl promoted, the expression of OsNAC45 in roots. Immunostaining showed that OsNAC45 was localized in all root cells and was mainly expressed in the stele. Loss of OsNAC45 decreased the sensitivity of rice plants to ABA and over-expressing this gene had the opposite effect, which demonstrated that OsNAC45 played an important role during ABA signal responses. Knockout of OsNAC45 also resulted in more ROS accumulation in roots and increased sensitivity of rice to salt stress. Transcriptome sequencing assay found that thousands of genes were differently expressed in OsNAC45-knockout plants. Most of the down-regulated genes participated in plant stress responses. Quantitative real time RT-PCR suggested that seven genes may be regulated by OsNAC45 including OsCYP89G1, OsDREB1F, OsEREBP2, OsERF104, OsPM1, OsSAMDC2, and OsSIK1. Conclusions These results indicate that OsNAC45 plays vital roles in ABA signal responses and salt tolerance in rice. Further characterization of this gene may help us understand ABA signal pathway and breed rice plants that are more tolerant to salt stress.

scholarly journals Action potentials induce biomagnetic fields in carnivorous Venus flytrap plants

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anne Fabricant ◽  
Geoffrey Z. Iwata ◽  
Sönke Scherzer ◽  
Lykourgos Bougas ◽  
Katharina Rolfs ◽  
...  
Keyword(s):  
Electrical Activity ◽  
Action Potentials ◽  
Plant Stress ◽  
Optically Pumped ◽  
Long Distance ◽  
Noninvasive Diagnostics ◽  
Venus Flytrap ◽  
Dionaea Muscipula ◽  
Cell Arrays ◽  
Electrical Signaling

AbstractUpon stimulation, plants elicit electrical signals that can travel within a cellular network analogous to the animal nervous system. It is well-known that in the human brain, voltage changes in certain regions result from concerted electrical activity which, in the form of action potentials (APs), travels within nerve-cell arrays. Electro- and magnetophysiological techniques like electroencephalography, magnetoencephalography, and magnetic resonance imaging are used to record this activity and to diagnose disorders. Here we demonstrate that APs in a multicellular plant system produce measurable magnetic fields. Using atomic optically pumped magnetometers, biomagnetism associated with electrical activity in the carnivorous Venus flytrap, Dionaea muscipula, was recorded. Action potentials were induced by heat stimulation and detected both electrically and magnetically. Furthermore, the thermal properties of ion channels underlying the AP were studied. Beyond proof of principle, our findings pave the way to understanding the molecular basis of biomagnetism in living plants. In the future, magnetometry may be used to study long-distance electrical signaling in a variety of plant species, and to develop noninvasive diagnostics of plant stress and disease.

More than just a pressure relief valve: physiological roles of volume-regulated LRRC8 anion channels

2019 ◽  
Vol 400 (11) ◽  
pp. 1481-1496 ◽  
Author(s):  
Lingye Chen ◽  
Benjamin König ◽  
Tianbao Liu ◽  
Sumaira Pervaiz ◽  
Yasmin S. Razzaque ◽  
...  
Keyword(s):  
Volume Regulation ◽  
Regulatory Volume Decrease ◽  
Anion Channel ◽  
Therapy Resistance ◽  
Cell Swelling ◽  
Organic Osmolytes ◽  
Anion Channels ◽  
Relief Valve ◽  
Wide Range ◽  
And Migration

Abstract The volume-regulated anion channel (VRAC) is a key player in the volume regulation of vertebrate cells. This ubiquitously expressed channel opens upon osmotic cell swelling and potentially other cues and releases chloride and organic osmolytes, which contributes to regulatory volume decrease (RVD). A plethora of studies have proposed a wide range of physiological roles for VRAC beyond volume regulation including cell proliferation, differentiation and migration, apoptosis, intercellular communication by direct release of signaling molecules and by supporting the exocytosis of insulin. VRAC was additionally implicated in pathological states such as cancer therapy resistance and excitotoxicity under ischemic conditions. Following extensive investigations, 5 years ago leucine-rich repeat-containing family 8 (LRRC8) heteromers containing LRRC8A were identified as the pore-forming components of VRAC. Since then, molecular biological approaches have allowed further insight into the biophysical properties and structure of VRAC. Heterologous expression, siRNA-mediated downregulation and genome editing in cells, as well as the use of animal models have enabled the assessment of the proposed physiological roles, together with the identification of new functions including spermatogenesis and the uptake of antibiotics and platinum-based cancer drugs. This review discusses the recent molecular biological insights into the physiology of VRAC in relation to its previously proposed roles.

Increased sensitivity of frog skeletal muscle to procaine in the presence of organic anions

1978 ◽  
Vol 56 (5) ◽  
pp. 739-746 ◽  
Author(s):  
J. G. Foulks ◽  
F. A. Perry
Keyword(s):  
Action Potentials ◽  
Time Course ◽  
Organic Anion ◽  
Organic Anions ◽  
Depressant Effect ◽  
Alkyl Sulfonates ◽  
Carboxylate Anions ◽  
Increased Sensitivity ◽  
Local Anaesthetic Action ◽  
Anaesthetic Action

In solutions containing an organic anion in place of chloride, frog toe muscles displayed increased sensitivity to the local anaesthetic action of procaine. Twitch inhibition by procaine in all media was accompanied by suppression of action potentials without change in membrane resting potentials. The twitch depressant effect of procaine was greater in solutions with carboxylate anions than with alkyl sulfonates. The intensity and the rapidity of onset of the effects of organic anions was related to the size of their hydrophobic component.Procaine accentuated acetate-induced reductions in the [K]0 required to produce K contractures and in the time course of submaximum K contractures. These effects were not shared by benzocaine. They were antagonized by increased [Ca]0.The results indicate that separate agents can exert mutually enhancing actions from opposite surfaces of the sarcolemma to facilitate the inactivation of depolarization-induced excitation–contraction coupling as well as that of the potential-dependent sodium channel.

Modulation of frequency and height of cytosolic calcium spikes by plasma membrane anion channels in guard cells

2021 ◽  
Author(s):  
Md Tahjib-Ul-Arif ◽  
Shintaro Munemasa ◽  
Toshiyuki Nakamura ◽  
Yoshimasa Nakamura ◽  
Yoshiyuki Murata
Keyword(s):  
Plasma Membrane ◽  
Stomatal Closure ◽  
Anion Channel ◽  
Guard Cells ◽  
Cytosolic Calcium ◽  
Peak Height ◽  
Extracellular Calcium ◽  
Wild Type ◽  
Anion Channels ◽  
In The Wild

Abstract Cytosolic calcium ([Ca2+]cyt) elevation activates plasma membrane anion channels in guard cells, which is required for stomatal closure. However, involvement of the anion channels in the [Ca2+]cyt elevation remains unclear. We investigated the involvement using Arabidopsis thaliana anion channel mutants, slac1-4 slah3-3 and slac1-4 almt12-1. Extracellular calcium induced stomatal closure in the wild-type plants but not in the anion channel mutant plants whereas extracellular calcium induced [Ca2+]cyt elevation both in the wild-type guard cells and in the mutant guard cells. The peak height and the number of the [Ca2+]cyt spike were lower and larger in the slac1-4 slah3-3 than in the wild-type and the height and the number in the slac1-4 almt12-1 were much lower and much larger than in the wild-type. These results suggest that the anion channels are involved in the regulation of [Ca2+]cyt elevation in guard cells.

scholarly journals Voltage-dependent block of endothelial volume-regulated anion channels by calix[4]arenes

1998 ◽  
Vol 275 (3) ◽  
pp. C646-C652 ◽  
Author(s):  
Guy Droogmans ◽  
Jean Prenen ◽  
Jan Eggermont ◽  
Thomas Voets ◽  
Bernd Nilius
Keyword(s):  
Open Channel ◽  
Single Channel ◽  
Anion Channel ◽  
Anion Channels ◽  
Channel Conductance ◽  
Open Channel Block ◽  
Maximum Inhibition ◽  
Voltage Dependent ◽  
A Site ◽  
Maximal Block

We have studied the effects of calix[4]arenes on the volume-regulated anion channel (VRAC) currents in cultured calf pulmonary artery endothelial cells. TS- and TS-TM-calix[4]arenes induced a fast inhibition at positive potentials but were ineffective at negative potentials. Maximal block occurred at potentials between 30 and 50 mV. Lowering extracellular pH enhanced the block and shifted the maximum inhibition to more negative potentials. Current inhibition was also accompanied by an increased current noise. From the analysis of the calix[4]arene-induced noise, we obtained a single-channel conductance of 9.3 ± 2.1 pS ( n = 9) at +30 mV. The voltage- and time-dependent block were described using a model in which calix[4]arenes bind to a site at an electrical distance of 0.25 inside the channel with an affinity of 220 μM at 0 mV. Binding occludes VRAC at moderately positive potentials, but calix[4]arenes permeate the channel at more positive potentials. In conclusion, our data suggest an open-channel block of VRAC by calix[4]arenes that also depends on the protonation of the binding site within the pore.

Intracellular compartmentation of organic anions within renal cells

1993 ◽  
Vol 264 (5) ◽  
pp. R882-R890 ◽  
Author(s):  
D. S. Miller ◽  
D. E. Stewart ◽  
J. B. Pritchard
Keyword(s):  
Organic Anion ◽  
Basolateral Membrane ◽  
Organic Anions ◽  
Epifluorescence Microscopy ◽  
Renal Cells ◽  
Bladder Epithelium ◽  
Opossum Kidney ◽  
Ok Cells ◽  
Intracellular Compartments ◽  
Energy Dependent

Epifluorescence microscopy and video-image analysis were used to measure the distribution of the monovalent organic anion fluorescein (FL) within the cells of three organic anion-secreting renal epithelia: crab urinary bladder (a proximal tubule analogue), opossum kidney (OK) cells in culture, and intact teleost proximal tubules. In all three preparations the intracellular FL distribution was nonuniform. Two distinct intracellular compartments were detected, one being diffuse and cytoplasmic and the other punctate. With low FL concentrations in the medium (1 microM and below) dye accumulation in the punctate compartment exceeded that of the cytoplasm. In crab bladder epithelium FL uptake into both compartments was inhibited by external probenecid, p-aminohippurate (PAH), and LiCl and stimulated by 10-50 microM external glutarate, suggesting that the punctate compartment loaded by a two-step mechanism: transport into the cytoplasm at the basolateral membrane, followed by accumulation at specific intracellular sites. Experiments in which FL was microinjected into OK cells directly demonstrated movement of FL from the cytoplasmic to the punctate compartment. Accumulation in the latter was specific, i.e., inhibitable by coinjected PAH and probenecid, and energy dependent. Together, these findings indicate that during secretion organic anions are sequestered within renal cells. The role of sequestration in overall transport remains to be determined.

Role of organic anions in renal response to dietary acid and base loads

1989 ◽  
Vol 257 (2) ◽  
pp. F170-F176 ◽  
Author(s):  
J. C. Brown ◽  
R. K. Packer ◽  
M. A. Knepper
Keyword(s):  
Organic Anion ◽  
Organic Anions ◽  
Acid Excretion ◽  
Acid Base Balance ◽  
Acid Base ◽  
Urine Ph ◽  
Renal Response ◽  
Base Balance ◽  
Net Acid Excretion

Bicarbonate is formed when organic anions are oxidized systemically. Therefore, changes in organic anion excretion can affect systemic acid-base balance. To assess the role of organic anions in urinary acid-base excretion, we measured urinary excretion in control rats, NaHCO3-loaded rats, and NH4Cl-loaded rats. Total organic anions were measured by the titration method of Van Slyke. As expected, NaHCO3 loading increased urine pH and decreased net acid excretion (NH4+ + titratable acid - HCO3-), whereas NH4Cl loading had the opposite effect. Organic anion excretion was increased in response to NaHCO3 loading and decreased in response to NH4Cl loading. We quantified the overall effect of organic ion plus inorganic buffer ion excretion on acid-base balance. The amounts of organic anions excreted by all animals in this study were greater than the amounts of NH4+, HCO3-, or titratable acidity excreted. In addition, in response to acid and alkali loading, changes in urinary organic anion excretion were 40-50% as large as changes in net acid excretion. We conclude that, in rats, regulation of organic anion excretion can contribute importantly to the overall renal response to acid-base disturbances.

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