Growth distribution and surface pH patterns along maize roots

Pilet, Paul‐Emile; Versel, Jean-Marc; Mayor, Guy

doi:10.1007/bf00397731

Cited by 77 publications

(53 citation statements)

References 30 publications

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“…However, in this study we found that there was strong acidification of external solution around the elongation region (pH, 4.8 instead of the bulk solution 5.2). This is in agreement with other reports (Pilet et al, 1983;Zieschang et al, 1993) and requires the active extrusion of H+ via H+-ATPases, which also generates the large negative membrane potential. Both passive and active H+ transport systems seem to be sensitive to external pH, changes.…”

Section: Gsupporting

confidence: 94%

Oscillations in H+ and Ca2+ Ion Fluxes around the Elongation Region of Corn Roots and Effects of External pH

1997

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Section: Gsupporting

confidence: 94%

Oscillations in H+ and Ca2+ Ion Fluxes around the Elongation Region of Corn Roots and Effects of External pH

1997

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“…Proton extrusion along individual roots of intact plants is well documented in relation to root extension growth (18,28) and geotropism (15). In both instances the proton extrusion is confined to the subapical root zones where extension growth takes place.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, electrogenic proton pumps can serve as the driving force for energy-dependent transmembrane movement of solutes, such as ions, sugars or amino acids. Furthermore, proton pumps are involved in the hormone-induced plant cell enlargement (17,18) as well as in regulation of cytoplasmic pH (24).…”

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confidence: 99%

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Localization and Capacity of Proton Pumps in Roots of Intact Sunflower Plants

Römheld¹,

Müller²,

Marschner³

1984

Plant Physiol.

193

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Proton extrusion by roots of intact sunflower plants (Helianthus annuas L.) was studied in nutrient solutions or in agar media with a pH indicator. Proton extrusion was enhanced by either iron deficiency, addition of fusicoccin, or single salt solutions of ammonium or potassium salts. The three types of proton extrusion differ in both localization along the roots and capacity. From their sensitivity to ATPase inhibitors it seems justified to characterize them as proton pumps driven by plasma membrane APTases.Enhanced proton extrusion induced by preferential cation uptake from (NH.)2SO4 or K2SO4 was uniformly distributed over the whole root system. In contrast, the enhancement effect of fusicoccin was confied to the basal root zones and that of iron deficiency to the apical root zones. Also the rates of proton extrusion per unit of root fresh weight differed remarkably and increased in the order. Fusicoccin << K2SO4< (NH4hSO4 < iron deficiency.Under iron deficiency the average values of proton extrusion for the whole root system are 5.6 micromoles H' per gram fresh weight per hour, however, for the apical root zones values of about 28 micromoles H can be calculated. This high capacity is most probably related to the iron deficiency-induced formation of rhizodermal transfer cells in the apical root zones. It can be assumed that the various types of root-induced acidification of the rhizosphere are of considerable ecological importance for the plant-soil relationships in general and for mobilization of mineral nutrients from sparingly soluble sources in particular.In higher plants, electrogenic proton pumps are localized in various membranes, such as the plasma membranes, tonoplast or mitochondrial membranes (1-4, 7). It importance. Acidification ofthe soil/root interface (rhizosphere) not only mobilizes mineral nutrients (e.g. P, Fe, Zn; [5,20]) but also affects the activity of microorganisms such as Rhizobium (16) or pathogenic fungi (23,27). This acidification of the rhizosphere can be easily demonstrated by agar techniques and depends on plant species, plant age, form and level of nutrient supply, and buffer capacity of the soil (13). Furthermore, deficiency of phosphorous (8) In this paper we report on results with intact sunflower plants on both the rate of proton extrusion and localization of proton pumps along roots as induced by iron deficiency, FC2 and different nutrient supply. In a following paper the properties of the iron deficiency-induced proton pumps will be described in more detail. MATERIALS AND METHODSGrowth of plants. Seeds of sunflower (Helianthus annuus L. cv Sobrid) were germinated for 3 d in quartz sand moistened with saturated CaS04 solution and subsequently transferred to a continuously aerated nutrient solution (25 plants per 1.5-L plas-

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“…Recent findings that cell wall acidification is associated with auxin effects on seed embryo growth (Rober-Kleber et al, 2003) and with early growth responses to gravistimulation of root cells (Taylor et al, 1996;Fasano et al, 2001) support the existence of a close relationship between wall acidification and cell expansion. Similarly, the spatial profile of growth rate along the elongation zone of maize roots has been shown to coincide with the spatial profile of rootsurface acidification (Pilet et al, 1983;Peters and Felle, 1999). Changes in cell wall acidification profiles could result from regulated changes in the activity of outward proton pumping H1 ATPase in the plasma membrane.…”

mentioning

confidence: 84%

The Spatially Variable Inhibition by Water Deficit of Maize Root Growth Correlates with Altered Profiles of Proton Flux and Cell Wall pH

Fan

Neumann

2004

Plant Physiology

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Growth of elongating primary roots of maize (Zea mays) seedlings was approximately 50% inhibited after 48 h in aerated nutrient solution under water deficit induced by polyethylene glycol 6000 at 20.5 MPa water potential. Proton flux along the root elongation zone was assayed by high resolution analyses of images of acid diffusion around roots contacted for 5 min with pH indicator gel. Profiles of root segmental elongation correlated qualitatively and quantitatively (r 2 5 0.74) with proton flux along the surface of the elongation zone from water-deficit and control treatments. Proton flux and segmental elongation in roots under water deficit were remarkably well maintained in the region 0 to 3 mm behind the root tip and were inhibited from 3 to 10 mm behind the tip. Associated changes in apoplastic pH inside epidermal cell walls were measured in three defined regions along the root elongation zone by confocal laser scanning microscopy using a ratiometric method. Finally, external acidification of roots was shown to specifically induce a partial reversal of growth inhibition by water deficit in the central region of the elongation zone. These new findings, plus evidence in the literature concerning increases induced by acid pH in wall-extensibility parameters, lead us to propose that the apparently adaptive maintenance of growth 0 to 3 mm behind the tip in maize primary roots under water deficit and the associated inhibition of growth further behind the tip are related to spatially variable changes in proton pumping into expanding cell walls.

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Growth distribution and surface pH patterns along maize roots

Cited by 77 publications

References 30 publications

Oscillations in H+ and Ca2+ Ion Fluxes around the Elongation Region of Corn Roots and Effects of External pH

Oscillations in H+ and Ca2+ Ion Fluxes around the Elongation Region of Corn Roots and Effects of External pH

Localization and Capacity of Proton Pumps in Roots of Intact Sunflower Plants

The Spatially Variable Inhibition by Water Deficit of Maize Root Growth Correlates with Altered Profiles of Proton Flux and Cell Wall pH

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