Distribution of growth and proton efflux in gravireactive roots of maize (Zea mays L.)

Versel, Jean-Marc; Pilet, Paul‐Emile

doi:10.1007/bf00446364

Cited by 27 publications

(18 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Other studies indicate accelerated growth along the upper side with no change along the lower side (Pilet and Nougarede 1974;Hofer et al 1976). In studies by Pilet and Ney (1981) and Versel and Pilet (1986) deceleration along the bottom accompanied by slight enhancement along the top was observed. Barlow and Rathfelder (1985) also reported a pattern of acceleration on the top and deceleration on the bottom during gravitropism in maize roots.…”

Section: Introductionmentioning

confidence: 79%

Computer-based video digitizer analysis of surface extension in maize roots

Ishikawa¹,

Hasenstein

Evans³

1991

Planta

107

View full text Add to dashboard Cite

We used a video digitizer system to measure surface extension and curvature in gravistimulated primary roots of maize (Zea mays L.). Downward curvature began about 25 +/- 7 min after gravistimulation and resulted from a combination of enhanced growth along the upper surface and reduced growth along the lower surface relative to growth in vertically oriented controls. The roots curved at a rate of 1.4 +/- 0.5 degrees min-1 but the pattern of curvature varied somewhat. In about 35% of the samples the roots curved steadily downward and the rate of curvature slowed as the root neared 90 degrees. A final angle of about 90 degrees was reached 110 +/- 35 min after the start of gravistimulation. In about 65% of the samples there was a period of backward curvature (partial reversal of curvature) during the response. In some cases (about 15% of those showing a period of reverse bending) this period of backward curvature occurred before the root reached 90 degrees. Following transient backward curvature, downward curvature resumed and the root approached a final angle of about 90 degrees. In about 65% of the roots showing a period of reverse curvature, the roots curved steadily past the vertical, reaching maximum curvature about 205 +/- 65 min after gravistimulation. The direction of curvature then reversed back toward the vertical. After one or two oscillations about the vertical the roots obtained a vertical orientation and the distribution of growth within the root tip became the same as that prior to gravistimulation. The period of transient backward curvature coincided with and was evidently caused by enhancement of growth along the concave and inhibition of growth along the convex side of the curve, a pattern opposite to that prevailing in the earlier stages of downward curvature. There were periods during the gravitropic response when the normally unimodal growth-rate distribution within the elongation zone became bimodal with two peaks of rapid elongation separated by a region of reduced elongation rate. This occurred at different times on the convex and concave sides of the graviresponding root. During the period of steady downward curvature the elongation zone along the convex side extended farther toward the tip than in the vertical control. During the period of reduced rate of curvature, the zone of elongation extended farther toward the tip along the concave side of the root. The data show that the gravitropic response pattern varies with time and involves changes in localized elongation rates as well as changes in the length and position of the elongation zone. Models of root gravitropic curvature based on simple unimodal inhibition of growth along the lower side cannot account for these complex growth patterns.

show abstract

Section: Introductionmentioning

confidence: 79%

Computer-based video digitizer analysis of surface extension in maize roots

Ishikawa¹,

Hasenstein

Evans³

1991

Planta

107

View full text Add to dashboard Cite

show abstract

“…On the other hand, several studies clearly related the locally restricted acidification along the roots of maize to the acid-growth mechanism (Peters 2004;Pilet et al 1983;Versel and Mayor 1985;Versel and Pilet 1986). These studies linked a local acidification 2-4 mm behind the root apex of maize roots to the highest level of root growth of this particular region.…”

Section: Discussionmentioning

confidence: 99%

Rhizosphere pH dynamics in trace-metal-contaminated soils, monitored with planar pH optodes

Bloßfeld

Perriguey²,

Sterckeman³

et al. 2009

Plant Soil

View full text Add to dashboard Cite

The present study presents new insights into pH dynamics in the rhizosphere of alpine pennycress (Noccaea caerulescens (J. Presl & C. Presl) F.K. Mey), maize (Zea mays L.) and ryegrass (Lolium perenne L.), when growing on three soils contaminated by trace metals with initial pH values varying from 5.6 to 7.4. The pH dynamics were recorded, using a recently developed 2D imaging technique based on planar pH optodes. This showed that alpine pennycress and ryegrass alkalinized their rhizosphere by up to 1.7 and 1.5 pH units, respectively, whereas maize acidified its rhizosphere by up to −0.7 pH units. The alkalinization by the roots of alpine pennycress and ryegrass was permanent and not restricted to specific root zones, whereas the acidification along the maize roots was restricted to the elongation zone and thus only temporary. Calculations showed that such pH changes should have noticeable effects on the solubility of the trace metal in the rhizosphere, and therefore on their uptake by the plants. As a result, it is suggested that models for trace metal uptake should include precise knowledge of rhizospheric pH conditions.

show abstract

“…Thus the expansion of the whole root would appear to be regulated by the cells of the cortex, in particular those of the inner layer. The gravitropic response in maize roots was suggested to be due to a differential acidification across the root, presumably producing a radial gradient in wall properties (Versel & Pilet, 1986), although this was not measured directly.…”

Section: Radial Location Of the Load-bearing Layersmentioning

confidence: 99%

The control of cell expansion in roots

Pritchard¹

1994

New Phytologist

153

View full text Add to dashboard Cite

SUMMARY The expansion of roots is considered at the level of the single cell. The water relations of cell expansion are discussed. Water entry, solute import and cell wall properties are considered as possible regulatory points. It is argued that root cell expansion can be understood in terms of cell turgor pressure and the physical properties of the cell wall, provided solute supply is not limiting. Various measurements of cell wall properties in roots are presented and the assumptions underlying their measurements are presented. It is concluded that cell wall properties must be measured over short time periods to prevent alterations in wall properties during the experiment. The radial location of the load‐bearing layers is discussed and it is concluded that, unlike aerial tissue, growth is limited by the properties of the inner layer of the root cortex. Evidence is presented to show that cell wall properties can change both during development and following turgor perturbation. In general, however, turgor itself is tightly regulated, particularly towards the root tip. A number of environmental situations are presented in which root growth is altered. The mechanism of the alteration is discussed at the single cell level. These 'stresses’include osmotic stress, low temperature and soil compaction. In many cases the alteration of root growth is consistent with changes in the ceil wall properties of the growing ceils. Severe stress, resulting in near cessation of root cell extension, can result in a change (usually an increase) in turgor pressure. The change in turgor pressure of the cells in the growing zone is smaller than that which would be expected from a continuation of an unstressed solute import rate. This exemplifies both the change in cell wall properties and the tight turgor homeostasis of root tips. The biochemical processes which underlie the modulation of cell wall properties are presented as they are currently understood in roots. Measurements of the chemical composition of the wall have not revealed any useful differences which can explain the developmental or stress‐induced changes in cell wall properties. Recent work on cell wall enzymes and proteins may provide information about control of cross‐linkages within the wall. In the last section the relative importance of apoplastic and symplastic solute transport to the expanding cells is considered. At present the consensus appears to favour the symplastic route, but the apoplastic pathway may also operate, possibly as a scavenging mechanism for leaked ions. The regulation of turgor pressure by linking solute import with wall loosening is discussed.

show abstract

Distribution of growth and proton efflux in gravireactive roots of maize (Zea mays L.)

Cited by 27 publications

References 24 publications

Computer-based video digitizer analysis of surface extension in maize roots

Computer-based video digitizer analysis of surface extension in maize roots

Rhizosphere pH dynamics in trace-metal-contaminated soils, monitored with planar pH optodes

The control of cell expansion in roots

Contact Info

Product

Resources

About