Modification of rhizosphere pH by the symbiotic legume Aspalathus linearis growing in a sandy acidic soil

2000 ◽  
Vol 27 (12) ◽  
pp. 1169 ◽  
Author(s):  
Mmboneni L. Muofhe ◽  
Felix. D. Dakora
Keyword(s):  
Nutrient Solution ◽  
Low Ph ◽  
Rhizosphere Ph ◽  
Rhizosphere Soils ◽  
A Value ◽  
Aspalathus Linearis ◽  
Legume Symbiosis ◽  
Solution Bathing ◽  
Uninoculated Control ◽  
Tea Production

Aspalathus linearis is a N2-fixing legume used for tea production, and grows in highly acidic soils (pH 3–5.3) of the Cederberg mountains in South Africa. Field and glasshouse studies revealed significantly higher pH in rhizosphere than non-rhizosphere soils. However, when six non-legume species were studied in adjacent fields, there were no differences in pH between rhizosphere and non-rhizosphere soils. The culture of A. linearis plants in sterile Leonard jars similarly showed a marked increase of 2.8 pH units in the nutrient solution bathing the roots of inoculated (nodulated) plants, compared to 1.5 pH units in uninoculated control. The uptake and reduction of NO3– by plants fed 2 mM NO3– also raised the rhizosphere pH by 3.5 units, a value comparable to that of the nodulated plants. The use of titrimetric methods showed that OH– and HCO3– were the components of alkalinity in the nutrient solution bathing roots of A. linearis, and were directly responsible for the increase in rhizosphere pH. These findings suggest that the ability to raise rhizosphere pH is an adaptative feature of this legume symbiosis that overcomes the adverse effects of low pH in enhancing nutrient acquisition and reducing trace element toxicity.

The stability of onoratoite, Sb8O11Cl2, in the supergene environment

2014 ◽  
Vol 78 (7) ◽  
pp. 1671-1675 ◽  
Author(s):  
Adam J. Roper ◽  
Peter Leverett ◽  
Timothy D. Murphy ◽  
Peter A. Williams
Keyword(s):  
Significant Influence ◽  
Secondary Phase ◽  
Low Ph ◽  
Stable Phase ◽  
Supergene Zone ◽  
A Value ◽  
Solubility Studies ◽  
The Stability ◽  
Very High

AbstractSynthesis and solubility studies of onoratoite have been undertaken to determine the role of this rare secondary phase in the immobilization of Sb and the conditions responsible for its formation in the supergene zone. Solubility studies were undertaken at 298.15 K. A value of ΔGfθ (Sb8O11Cl2, s, 298.15 K) = –2576 ±12 kJ mol–1 was derived. Calculations involving sénarmontite, Sb2O3, klebelsbergite, Sb4O4SO4(OH)2 and schafarzikite, FeSb2O4, show that onoratoite is a thermodynamically stable phase only at negligible activities of SO42–(aq) and low activities of Fe2+(aq), at low pH and very high activities of Cl–(aq). This explains why onoratoite is such a rare secondary phase and why it cannot exert any significant influence on the dispersion of Sb in the supergene environment.

scholarly journals Evaluasi Ketahanan Plasma Nutfah Kenaf terhadap Cekaman Fe pada pH Masam Evaluation of Kenaf Germplasm to High Fe Concentration and Low pH Resistance

2016 ◽  
Vol 1 (1) ◽  
pp. 28
Author(s):  
Rully Dyah Purwati ◽  
. Marjani
Keyword(s):  
Plant Breeding ◽  
Nutrient Solution ◽  
Block Design ◽  
Dry Weight ◽  
Low Ph ◽  
Green House ◽  
Neutral Ph ◽  
Excess Fe

<p>Penelitian bertujuan untuk mendapatkan informasi ketahanan plasma nutfah kenaf pada lingkungan konsentrasi Fe yang ekstrim dan pH masam telah dilaksanakan di Laboratorium dan Rumah Kaca Pemuliaan Balittas, Malang, mulai bulan Januari–Desember 2008. Penelitian dilaksanakan dengan menggunakan ran-cangan acak kelompok yang diulang 3 kali. Bahan penelitian terdiri dari 100 aksesi kenaf yang diuji di labo-ratorium pada tingkat bibit. Pada setiap ulangan, masing-masing aksesi kenaf diuji sebanyak 20 bibit ber-umur 3–4 hari, yang ditanam pada stereo-<em>foam</em> berlapiskan kasa strimin. Bibit dipelihara pada larutan nu-trien ”<em>Yoshida”</em> dan diberi perlakuan konsentrasi unsur Fe 350 ppm dan pH 4. Sebagai pembanding diguna-kan nutrien yang sama dengan konsentrasi Fe = 0 ppm dan pH netral. Pengamatan dilakukan terhadap pan-jang akar, panjang hipokotil, berat kering akar, dan berat kering hipokotil. Hasil penelitian menunjukkan bahwa ketahanan 100 aksesi kenaf yang diuji terhadap kelebihan Fe pada pH masam bervariasi; tetapi ada 8 aksesi yang tergolong tahan, yaitu aksesi nomer 449, 461, 476, 782, 785, 833, 836, dan 839.</p><p>The objective of this experiment was to find out information of kenaf germplasm resistance to high Fe con-centration and low pH of media. The experiment was conducted in laboratory and green house of plant breeding division, IToFCRI, Malang from January to December 2008. The experiment was designed in ran-domized block design with three replications. One hundred accessions of kenaf seedlings were evaluated in laboratory. Each accession in each replicate consisted of 20 seedlings (3–4 days old) were planted in stereo-foam trays with plastic gauze layer. Seedlings were maintained in “Yoshida” nutrient solution and treated with 350 ppm Fe concentration and pH 4. The same media with 0 ppm Fe and neutral pH was used as a control. The parameters observed were root and hypocotyls length, root and hypocotyls dry weight. Results of this experiment showed that the resistance to excess Fe in low pH of 100 accessions evaluated were va-ried. Out of 100 accessions, eight accessions were categorised as resistant i.e. accession no. 449, 461, 476, 782, 785, 833, 836, and 839.</p>

Ba++ on the resting frog stomach: effects on electrical and secretory parameters

1975 ◽  
Vol 228 (2) ◽  
pp. 511-517 ◽  
Author(s):  
PK Rangachari
Keyword(s):  
Acid Secretion ◽  
Nutrient Solution ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Secretory Rate ◽  
Frog Stomach ◽  
Solution Bathing ◽  
Per Se

Ba++ added to the nutrient solution bathing the resting frog stomach increased resistance, decreased the PD, and stimulated acid secretion. Under short-circuit conditions, the increase in H+-secretory rate was accompanied by a decrease in short-circuit current (I-sc). These changes were reversed by NaSCN (10 mM), suggesting that Ba++ had not impaired the current-generating mechanism per se. Histamine-induced acid secretion was associated with an increase in net Cl- flux, particularly in the N yields S flux (JNS). Ba++ increased acid secretion with no increase in JNS and a decrease in net Cl- flux. The effects of Ba++ were amplified by low-Cl- solutions. Histamine, in the presence of Ba++ and low-Cl- solutions, increased acid secretion and transmucosal resistance, suggesting the operation of a neutral pump in the secretion of HCl. It is concluded that Ba++ limits Cl- entry and also acts as a secretagogue.

Synergistic Degradation of Acid Scarlet Dyeing Wastewater by the Ultrasound/Fenton Method

2013 ◽  
Vol 448-453 ◽  
pp. 34-37
Author(s):  
Tong Liu ◽  
Feng Wei He ◽  
Ya Qin Zhang
Keyword(s):  
Degradation Rate ◽  
Low Ph ◽  
Mass Ratio ◽  
Dyeing Wastewater ◽  
Fenton Reagent ◽  
Initial Concentration ◽  
A Value ◽  
Ultrasonic Technology ◽  
Initial Ph ◽  
Synergistic Degradation

Degradation of simulated acid scarlet (GR) wastewater by ultrasonic technology , Fenton reagentoxidation , and a combination of the two processes was studied. It was found that extent of degradation by ultrasonic technology or Fenton reagent oxidation alone was poor , with values of 4 % and 40 % respectively. The extent of degradation was significantly enhanced when the two processes were combined , with a value of up to 90 % , which shows that these two processes have a good synergistic effect and can shorten the reaction time.Also discussed the initial concentration, initial pH, Fe2+ and H2O2 dosage and other factors on the degradation of acid scarlet. The results show that the degradation rate of pH significant effect on the low pH is conducive to degradation. Degradation rate with the dosage of H2O2 and FeSO4 temperature increased, but when acid scarlet with H2O2 and Fe2+ the mass ratio of 100:15:41, the degradation rate reached 96.6%.

Aspalathus linearis(Rooibos tea) as potential phytoremediation agent: a review on tolerance mechanisms for aluminum uptake

2013 ◽  
Vol 21 (2) ◽  
pp. 85-92 ◽  
Author(s):  
Sheku A. Kanu ◽  
Jonathan O. Okonkwo ◽  
Felix D. Dakora
Keyword(s):  
Contaminated Soils ◽  
Arbuscular Mycorrhizae ◽  
Am Fungi ◽  
Aluminum Concentration ◽  
Cluster Roots ◽  
Rhizosphere Ph ◽  
Acidic Soils ◽  
Economic Implications ◽  
Aspalathus Linearis ◽  
Rooibos Tea

Aspalathus linearis (Burm. F.) R. Dahlg., commonly referred to as Rooibos tea, grows naturally in nutrient-poor, sandy, acidic soils (pH 3–5.3) with high aluminum concentration ranging from 110 to 275 μg Al g−1in the Cederberg’s mountainous areas in South Africa. Earlier studies found significant differences in Al concentration in organs of A. linearis, with roots having higher amounts (1262–4078 μg Al g−1), suggesting that the plant is capable of accumulating excess Al in acidic soils. Identification of the mineralogical constituents of organs of A. linearis using X-ray diffraction (XRD) analysis revealed the presence of an Al–Si complex (aluminosilicate or hydroxyaluminosilicate (HAS) species) in the shoot and root, possibly to internally ameliorate Al toxicity. In addition, A. linearis has specialized cluster roots that exude Al-chelating organic acid ligands such as citric, malic, and malonic acids. Organic acids can bind strongly to Al in the plant and rhizosphere to reverse its phytotoxic effects to the plants. Field and glasshouse studies revealed significant differences in pH between rhizosphere and nonrhizosphere soils of A. linearis and also showed that roots of the plant release OH−and HCO3−anions to raise rhizosphere pH possibly to immobilize Al through complexation. Furthermore, A. linearis is easily infected by arbuscular mycorrhizae (AM) fungi, but mycorrhizal associations are known to inhibit transport of metallic cations into plant roots. These features of A. linearis are perceived as good indicators for bioremediation; and the plant could, therefore, be a suitable candidate for phytoremediation technologies such as phytoaccumulation, phytostabilization, and phytodegradation. The environmental and economic implications of the potential of A. linearis to bioremediate Al-contaminated soils are briefly discussed. Furthermore, this review briefly highlights future studies investigating the utilization of the shoot of A. linearis as adsorbent for the removal of trace and (or) heavy metal from aqueous solutions.

scholarly journals Influence of Aluminum at Low pH on the Rhizosphere Processes of Masson Pine (Pinus Massoniana Lamb)

2021 ◽  
Author(s):  
Wang Ping ◽  
Zhou Sijie ◽  
Li Ao ◽  
Xie Linbei
Keyword(s):  
Amino Acids ◽  
Secondary Metabolites ◽  
Oxalic Acid ◽  
Malic Acid ◽  
Low Ph ◽  
Al Toxicity ◽  
Rhizosphere Ph ◽  
Endogenous Hormones ◽  
Masson Pine ◽  
Rhizosphere Acidification

Abstract Trees in general are very tolerant of aluminum (Al, mainly Al3+ at pH ≦ 5.0), and the small effects seen in the contaminated soils may mislead people that the contamination is unimportant. We believe that the assessments with Al-sensitive Masson pine could have revealed a bigger difference. The key point of this study was to characterize the Al toxicity for Masson Pine. The objectives were to discover the specific eco-physiological relationship between pine roots and rhizosphere Al, and to investigate the Al effects on several parameters, measured in the rhizosphere of Masson pine. Masson pine seedlings were cultivated on a hydroponic setup. Through comprehensive laboratory dose-gradient experiments, Al-triggered composition of the root-released compounds and several rhizospheric parameters were determined by chromatography or spectroscopy. This study gives an important evidence of the Al-toxicity effects on the composition of root-released compounds and the root growth of Masson pine. Results showed that higher rhizospheric Al at pH 4.5 might contribute to increased release of sugars, and also could stimulate the release of oxalic acid and malic acid. The total of secreted amino acids were correlated with the rhizosphere Al. Zero additional Al induced no rhizosphere pH elevation, but Al-induced rhizosphere acidification (pH from 4.50 to 4.22) was observed at Al 100 µM. Greater additions of Al (>300 µM) suppressed the rhizosphere acidification at pH 3.92. Added Al had a negative effect on the dry weight of pine roots, but an opposite effect on Al accumulated in the roots was observed. The four endogenous hormones were also determined in the pine roots. Gibberellic acid (GA3) decreased, whereas abscisic acid (ABA) increased simultaneously with the addition of Al. Their inflexional concentrations were most frequently observed at 100 µM, which might be the threshold of Al toxicity for Masson pine. The secondary metabolites assayed have been studied in relation to the rhizospheric Al. The rhizosphere Al species at low pH can trigger pine roots to release the sugars (glucose, fructose + aldose), organic acids (oxalic acid, and malic acid), amino acids, secondary metabolites, and endogenous hormones during their growth. Meanwhile it also affected the growth of pine roots. This is an extensive study, which can help understanding the toxicity of Al to this important pioneer species of acid forest soils in south China.

scholarly journals Relationship between hemagglutinin stability and influenza virus persistence after exposure to low pH or supraphysiological heating

2021 ◽  
Vol 17 (9) ◽  
pp. e1009910
Author(s):  
Guohua Yang ◽  
Chet R. Ojha ◽  
Charles J. Russell
Keyword(s):  
Thermal Stability ◽  
Influenza A ◽  
Point Mutations ◽  
Low Ph ◽  
Surface Glycoprotein ◽  
Luciferase Reporter ◽  
Reporter Assay ◽  
Ph Values ◽  
A Value ◽  
Animal Isolates

The hemagglutinin (HA) surface glycoprotein is triggered by endosomal low pH to cause membrane fusion during influenza A virus (IAV) entry yet must remain sufficiently stable to avoid premature activation during virion transit between cells and hosts. HA activation pH and/or virion inactivation pH values less than pH 5.6 are thought to be required for IAV airborne transmissibility and human pandemic potential. To enable higher-throughput screening of emerging IAV strains for “humanized” stability, we developed a luciferase reporter assay that measures the threshold pH at which IAVs are inactivated. The reporter assay yielded results similar to TCID50 assay yet required one-fourth the time and one-tenth the virus. For four A/TN/09 (H1N1) HA mutants and 73 IAVs of varying subtype, virion inactivation pH was compared to HA activation pH and the rate of inactivation during 55°C heating. HA stability values correlated highly with virion acid and thermal stability values for isogenic viruses containing HA point mutations. HA stability also correlated with virion acid stability for human isolates but did not correlate with thermal stability at 55°C, raising doubt in the use of supraphysiological heating assays. Some animal isolates had virion inactivation pH values lower than HA activation pH, suggesting factors beyond HA stability can modulate virion stability. The coupling of HA activation pH and virion inactivation pH, and at a value below 5.6, was associated with human adaptation. This suggests that both virologic properties should be considered in risk assessment algorithms for pandemic potential.

scholarly journals The Rhizobium-Legume Symbiosis: Co-opting Successful Stress Management

2022 ◽  
Vol 12 ◽  
Author(s):  
Justin P. Hawkins ◽  
Ivan J. Oresnik
Keyword(s):  
Model System ◽  
Low Ph ◽  
Complex Signal ◽  
Tolerance Mechanisms ◽  
Positive Interaction ◽  
Bacterial Response ◽  
Plant Peptides ◽  
Legume Symbiosis ◽  
Growth Inhibiting ◽  
Signal Exchange

The interaction of bacteria with plants can result in either a positive, negative, or neutral association. The rhizobium-legume interaction is a well-studied model system of a process that is considered a positive interaction. This process has evolved to require a complex signal exchange between the host and the symbiont. During this process, rhizobia are subject to several stresses, including low pH, oxidative stress, osmotic stress, as well as growth inhibiting plant peptides. A great deal of work has been carried out to characterize the bacterial response to these stresses. Many of the responses to stress are also observed to have key roles in symbiotic signaling. We propose that stress tolerance responses have been co-opted by the plant and bacterial partners to play a role in the complex signal exchange that occurs between rhizobia and legumes to establish functional symbiosis. This review will cover how rhizobia tolerate stresses, and how aspects of these tolerance mechanisms play a role in signal exchange between rhizobia and legumes.

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