Organic anions in the rhizosphere of Al-tolerant and Al-sensitive wheat lines grown in an acid soil in controlled and field environments

Soil Research ◽  
2008 ◽  
Vol 46 (3) ◽  
pp. 257 ◽  
Author(s):  
C. R. Schefe ◽  
M. Watt ◽  
W. J. Slattery ◽  
P. M. Mele

Several sampling methods were investigated for the quantification of organic anions in the rhizosphere of Al-tolerant (ET8) and Al-sensitive (ES8) wheat plants in soil systems. Controlled environment studies used anion exchange membranes to collect rhizosphere organic anions (from root tips and mature regions of nodal roots) from ET8 and ES8 plants at the 6-leaf stage in a glasshouse environment. Using the anion exchange membranes, a selection of organic anions were detected on the tips and mature regions of roots, with ET8 and ES8 having similar rhizosphere organic anion profiles. The field experiment used 2 established methods of organic anion collection: rhizosphere soil and root washings. The ET8 and ES8 wheat lines had similar levels of organic anions, including malate, in the rhizosphere (using soil shaken from roots and root washings) at 3 sampling times (4 and 6 leaves, and flowering). The rhizosphere organic anions differed significantly from the bulk soil, with the concentration and range of organic anions in the rhizosphere decreasing towards flowering, presumably due to physiological changes in plant and root growth. This study used several techniques to investigate organic anion exudation by roots, with organic anions detected using all techniques. However, technical limitations of these techniques were recognised: (i) the lack of simultaneous exposure of root tips to both the anion exchange membrane and the chemical stimulant, e.g. Al3+; and (ii) the inability to derive the origin of organic anions measured in rhizosphere soil and root washings. The challenge for future soil-based organic anion research is to identify the dominant stress that has triggered an exudation response (i.e. Al toxicity, P deficiency), and to clearly differentiate between plant- and microbial-derived contributions to exudation.

2018 ◽  
Author(s):  
Yanliang Wang ◽  
Erik Lysøe ◽  
Tegan Armarego-Marriott ◽  
Alexander Erban ◽  
Lisa Paruch ◽  
...  

AbstractRoot and root-released organic anions play important roles in uptake of phosphorus (P), an essential macronutrient for food production. Oat, ranking sixth in the world’s cereal production, contains valuable nutritional compounds and can withstand poor soil conditions. The aim of this research was to investigate root transcriptional and metabolic responses of oat grown under P-deficient and P-sufficient conditions. We conducted a hydroponic experiment and measured root morphology, organic anions exudation, and analysed changes in the transcriptome and metabolome, to understand oat root adaptation to P deficiency. We found that oat roots showed enhanced citrate and malate exudation after four weeks of P-deficiency. After 10 days of P-deficiency, we identified 9371 differentially expressed transcripts with a two-fold or greater change (p < 0.05): forty-eight sequences predicted to be involved in organic anion biosynthesis and efflux were consistently up-regulated; twenty-four up-regulated transcripts in oat were also found up-regulated upon P starvation in rice and wheat under similar conditions. Phosphorylated metabolites (i.e. glucose-6-phosphate, myo-inositol-phosphate) reduced dramatically, while citrate and malate, some sugars and amino acids increased slightly in P-deficient oat roots. Our data provide new insights into the root responses to P deficiency and root-released organic anions in oat.HighlightWe found oat- a monocot food crop, showed high exudation rate of citrate under phosphorus deficiency; root transcriptome and metabolome were then investigated to understand oat adaptation to P deficiency.


2004 ◽  
Vol 31 (11) ◽  
pp. 1075 ◽  
Author(s):  
Ayalew Ligaba ◽  
Mineo Yamaguchi ◽  
Hong Shen ◽  
Takayuki Sasaki ◽  
Yoko Yamamoto ◽  
...  

The response of greater purple lupin (Lupinus pilosus L.) to a combination of phosphorus (P) deficiency and aluminium (Al) toxicity is unknown, and the mechanisms involved in the exudation of organic anions from greater purple lupin have not been reported. Therefore, plants grown with (+P) or without (–P) 250 µm P were exposed to 0 or 50 µm AlCl3 and the amount of organic anions exuded and the activities of plasma membrane H+-ATPase (E.C 3.6.3.6) and H+-pumps were investigated. Twenty days of P deficiency resulted in significantly reduced shoot growth and increased proteoid root formation. Exposure to 50 µm AlCl3 did not induce citrate exudation but did induce some malate exudation in –P plants. In contrast, P deficiency did induce exudation of citrate. Enhanced citrate exudation was attributed to the large increase in the activity of plasma membrane H+-ATPase and associated H+ transport. This was shown by the inhibitory effect of vanadate on plasma membrane H+-ATPase activity in vitro and on citrate exudation in vivo. However, vanadate did not suppress the exudation of malate. During 9 h of Al exposure, exudation of citrate showed a continuing increase for both –P and +P plants, while malate exudation increased only during the first 3 h, after which it rapidly declined. The total amount of organic anion exudation was significantly higher for –P plants. In the presence of 50 µm anion channel blockers [anthracene-9-carboxylic acid (A-9-C), niflumic acid (NIF) and phenylglyoxal (PG)], the exudation of citrate and malate was reduced by 25–40%. It was concluded that P deficiency induces citrate exudation by enhancing the activity of plasma membrane H+-ATPase and H+ export. In L. pilosus, exudation of organic anions occurs primarily in response to P deficiency but not Al toxicity. This contrasts with previous results obtained in Brassica napus L.


2008 ◽  
Vol 311 (1-2) ◽  
pp. 336-348 ◽  
Author(s):  
Chao-Shuan Chang ◽  
Ho-Sheng Ni ◽  
Shing-Yi Suen ◽  
Wen-Chi Tseng ◽  
Hsin-Cheng Chiu ◽  
...  

2011 ◽  
Vol 36 (11) ◽  
pp. 1521-1557 ◽  
Author(s):  
Guillaume Couture ◽  
Ali Alaaeddine ◽  
Frédéric Boschet ◽  
Bruno Ameduri

2021 ◽  
Author(s):  
Joshua Osuofa ◽  
Daniel Henn ◽  
Jinxiang Zhou ◽  
Anna Forsyth ◽  
Scott M. Husson

Membranes ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 311
Author(s):  
Muhammad Imran Khan ◽  
Majeda Khraisheh ◽  
Fares AlMomani

Recycling of acid from aqueous waste streams is crucial not only from the environmental point of view but also for maturing the feasible method (diffusion dialysis). Anion exchange membrane (AEM)–based diffusion dialysis process is one of the beneficial ways to recover acid from aqueous waste streams. In this article, the synthesis of a series of brominated poly (2, 6–dimethyl-1, 4–phenylene oxide) (BPPO)-based anion exchange membranes (AEMs) through quaternization with triphenylphosphine (TPP) were reported for acid recovery via diffusion dialysis process. The successful synthesis of the prepared membranes was confirmed by Fourier transform infrared (FTIR) spectroscopy. The as-synthesized anion exchange membranes represented water uptake (WR) of 44 to 66%, ion exchange capacity of (IEC) of 1.22 to 1.86 mmol/g, and linear swelling ratio (LSR) of 8 to 20%. They exhibited excellent thermal, mechanical, and acid stability. They showed homogeneous morphology. The acid recovery performance of the synthesized AEMs was investigated in a two compartment stack using simulated mixture of HCl and FeCl2 as feed solution at room temperature. For the synthesized anion exchange membranes TPP–43 to TPP–100, the diffusion dialysis coefficient of acid (UH+) was in the range of 6.7 to 26.3 (10−3 m/h) whereas separation factor (S) was in the range of 27 to 49 at 25 °C. Obtained results revealed that diffusion dialysis performance of the synthesized AEMs was higher than the commercial membrane DF–120B (UH+ = 0.004 m/h, S = 24.3) at room temperature. It showed that the prepared AEMs here could be excellent candidates for the diffusion dialysis process.


2021 ◽  
Vol 22 (3) ◽  
pp. 1415
Author(s):  
Veronika Sarapulova ◽  
Natalia Pismenskaya ◽  
Valentina Titorova ◽  
Mikhail Sharafan ◽  
Yaoming Wang ◽  
...  

The interplay between the ion exchange capacity, water content and concentration dependences of conductivity, diffusion permeability, and counterion transport numbers (counterion permselectivity) of CJMA-3, CJMA-6 and CJMA-7 (Hefei Chemjoy Polymer Materials Co. Ltd., China) anion-exchange membranes (AEMs) is analyzed using the application of the microheterogeneous model to experimental data. The structure–properties relationship for these membranes is examined when they are bathed by NaCl and Na2SO4 solutions. These results are compared with the characteristics of the well-studied homogenous Neosepta AMX (ASTOM Corporation, Japan) and heterogeneous AMH-PES (Mega a.s., Czech Republic) anion-exchange membranes. It is found that the CJMA-6 membrane has the highest counterion permselectivity (chlorides, sulfates) among the CJMAED series membranes, very close to that of the AMX membrane. The CJMA-3 membrane has the transport characteristics close to the AMH-PES membrane. The CJMA-7 membrane has the lowest exchange capacity and the highest volume fraction of the intergel spaces filled with an equilibrium electroneutral solution. These properties predetermine the lowest counterion transport number in CJMA-7 among other investigated AEMs, which nevertheless does not fall below 0.87 even in 1.0 eq L−1 solutions of NaCl or Na2SO4. One of the reasons for the decrease in the permselectivity of CJMAED membranes is the extended macropores, which are localized at the ion-exchange material/reinforcing cloth boundaries. In relatively concentrated solutions, the electric current prefers to pass through these well-conductive but nonselective macropores rather than the highly selective but low-conductive elements of the gel phase. It is shown that the counterion permselectivity of the CJMA-7 membrane can be significantly improved by coating its surface with a dense homogeneous ion-exchange film.


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