Electrical currents associated with arbuscular mycorrhizal interactions

Berbara, Ricardo Luís Louro; Morris, B. M.; Fonseca, Henrique M.A.C.; Reid, Brian; Gow, Neil A. R.; Daft, M. J.

doi:10.1111/j.1469-8137.1995.tb04314.x

Cited by 36 publications

(22 citation statements)

References 44 publications

(74 reference statements)

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“…Our observations that external acidic pH of 4.0 to 4.5 caused multiple and successive formation of germ tubes with limited growth could be in agreement with the assumption of an ATPase proton-pump regulatory mechanism (Harold, 1994;Berbara et al, 1995). Under these acidic conditions, the germ-tube metabolism may have been energetically insufficient for supporting the alkalinization action of the H ϩ -ATPase pumps (Gout et al, 1992).…”

Section: Characteristic Ph Profilesupporting

confidence: 76%

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Intracellular pH in Arbuscular Mycorrhizal Fungi1

et al. 1998

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A method was developed to perform real-time analysis of cytosolic pH of arbuscular mycorrhizal fungi in culture using dye and ratiometric measurements (490/450 nm excitations). The study was mainly performed using photometric analysis, although some data were confirmed using image analysis. The use of nigericin allowed an in vivo calibration. Experimental parameters such as loading time and concentration of the dye were determined so that pH measurements could be made for a steady-state period on viable cells. A characteristic pH profile was observed along hyphae. For Gigaspora margarita, the pH of the tip (0-2 m) was typically 6.7, increased sharply to 7.0 behind this region (9.5 m), and decreased over the next 250 m to a constant value of 6.6. A similar pattern was obtained for Glomus intraradices. The pH profile of G. margarita germ tubes was higher when cultured in the presence of carrot (Daucus carota) hairy roots (nonmycorrhizal). Similarly, extraradical hyphae of G. intraradices had a higher apical pH than the germ tubes. The use of a paper layer to prevent the mycorrhizal roots from being in direct contact with the medium selected hyphae with an even higher cytosolic pH. Results suggest that this method could be useful as a bioassay for studying signal perception and/or H ؉ cotransport of nutrients by arbuscular mycorrhizal hyphae.

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Section: Characteristic Ph Profilesupporting

confidence: 76%

“…Working on mycorrhizal interactions, Berbara et al (1995) showed an inward current at the tip of young G. margarita germ tubes. Since electrical currents are thought to be carried mainly by Figure 8.…”

Section: Characteristic Ph Profilementioning

confidence: 99%

Intracellular pH in Arbuscular Mycorrhizal Fungi1

et al. 1998

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“…This would explain the small currents seen in Gi. margarita (Berbara et al, 1995) and might explain the variability in p.d. observed between germ tubes ( (Leigh et al, 1994) that cytoplasmic [K + ] concentration would be allowed to fall below c. 50 mM to the low concentrations ( 15 mM) required to balance the Nernst relationship.…”

Section: Effect Of Changing External [K + ]mentioning

confidence: 99%

“…margarita was chosen for these experiments because its spores are large ( 100 µm diameter) and because it has been used in other studies of germtube physiology (Thomson et al, 1990 ;Lei et al, 1991 ;Berbara et al, 1995).…”

Section: Germ Tubesmentioning

confidence: 99%

Transmembrane electric potential difference of germ tubes of arbuscular mycorrhizal fungi responds to external stimuli

Ayling

Smith

2000

New Phytologist

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Measurements of the electric potential difference across the hyphal wall and the cell membrane were made on external hyphae of three species of arbuscular mycorrhizal fungus Gigaspora margarita, Scutellospora calospora and Glomus coronatum and on germ tubes of Gi. margarita. The values of transmembrane electric potential difference recorded ("k40 mV) are less negative than those previously reported from hyphae of arbuscular mycorrhizal fungi closely associated with roots and from filamentous fungi. The external hyphae of arbuscular mycorrhizal fungi grown in soil had similar values of electric potential difference to those grown in soil-less culture, and to germ tubes. Thermodynamic calculations showed that despite these low values of electric potential difference, efficient high-affinity uptake of phosphate is possible. The transmembrane electric potential difference of germ tubes of Gi. margarita became more negative when plant root extract was added to the medium, showing for the first time that the early stages of interaction between plant and fungus occur via direct effects on the plasma membrane rather than via effects on gene expression. Addition of K + reversibly depolarized the transmembrane electric potential difference of germ tubes of Gi. margarita, indicating that despite the low electric potential difference the fungus has control over the permeability of the plasmamembrane to K + .

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“…Roots supplemented with humic substances present varying responses, including: positive influence on transportation and facilitation of the uptake of ions; increased respiration and rates of reactions that occur in the Krebs cycle, ensuring an increase in adenosine triphosphate (ATP) production; increased synthesis of nucleic acids and chlorophyll content and also an increase or inhibition of enzymes (Nannipieri et al 1993;Façanha et al 2002). In addition, biochemical mechanisms, such as ATPase activity, are stimulated by certain levels of HA (Varanini et al 1993;Berbara et al 1995;Façanha et al 2002;Canellas et al 2002).…”

Section: Resultsmentioning

confidence: 99%

Biostimulation of inoculation with Glomus proliferum and application of humic acid in the in vitro growth of Lunularia cruciata

et al. 2013

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In this study, we evaluated the growth of the liverwort Lunularia cruciata, inoculated or not with the arbuscular mycorrhizal fungi (AMF) Glomus proliferum (15 spores per Petri dish), in Strullu-Romand Variant (SRV) medium modified and enriched with humic acid (HA) at different concentrations (0, 20, 40 and 80 mg C L −1 ), as well as the sporulation of the AMF. We assessed the absolute growth rate (AGR) and relative growth rate (RGR) at inoculation, as well as at 7, 14, 21, 28, 43, 52 and 60 days after inoculation (DAI), whereas we assessed sporulation at 25, 43, 60 and 70 DAI. The main determinant of L. cruciata growth was the presence of AMF. With and without G. proliferum inoculation, respectively, the AGR peaked at 39 and 42 DAI, and the RGR was 0.0474 and 0.0387 cm 2 cm −2 d −1 . Doses of 20 and 80 mg C L −1 of HA had a positive influence on the growth of L. cruciata. With and without HA, respectively, the AGR peaked at 38 and 39 DAI, and the RGR was 0.0484 and 0.0422 cm 2 cm −2 d −1 . The sporulation of G. proliferum, which was as high as 199 spores plate −1 , was influenced by HA, especially at 20 and 80 mg C L −1 .

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Electrical currents associated with arbuscular mycorrhizal interactions

Cited by 36 publications

References 44 publications

Intracellular pH in Arbuscular Mycorrhizal Fungi1

Intracellular pH in Arbuscular Mycorrhizal Fungi1

Transmembrane electric potential difference of germ tubes of arbuscular mycorrhizal fungi responds to external stimuli

Biostimulation of inoculation with Glomus proliferum and application of humic acid in the in vitro growth of Lunularia cruciata

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