Distribution and redistribution of extension growth along vertical and horizontal gravireacting maize roots

Barlow, PW; Rathfelder, Erica L.

doi:10.1007/bf00392222

Cited by 61 publications

(41 citation statements)

References 17 publications

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“…Rather, the efflux appeared to be synchronized in the youngest cells of the elongation zone. The onset of proton efflux from the upper surface was just before or coincident with the onset of downward bending, which occurs 12 to 15 min after gravistimulation in maize (1,12,25), and two recent reports show that the early stages of the bending response may also develop simultaneously in the youngest cells of the elongation zone. Zieschang and Sievers (31) located a small group of cells at the beginning of the elongation zone in the upper epidermis of Phleum pratense roots where elongation was first seen, with the response detectable slightly later in cells on either side of this region.…”

Section: Gravistimulated Rootmentioning

confidence: 77%

Ionic Current Changes Associated with the Gravity-Induced Bending Response in Roots of Zea mays L.

Collings¹,

White²,

Overall³

1992

Plant Physiol.

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A vibrating probe was used to measure the changes in ionic currents around gravistimulated roots of Zea mays L. in an effort to determine whether these currents are involved in stimulus transduction from the root cap to the elongation zone. We did not observe a migration of the previously reported auxin-insensitive current efflux associated with gravity sensing (T. Bjorkman, A.C.Leopold [1987] Plant Physiol 84: 841-846) back from the root cap.Instead, beginning 10 to 15 min after gravistimulation, an asymmetry in current developed simultaneously along the root around the meristem and apical regions of the elongation zone. This asymmetry comprised a proton efflux from the upper surface, which was superimposed on the symmetrical pattern around the vertical root. The gravity-induced proton efflux was inhibited by the application of the auxin transport inhibitor, 2,3,5-triiodobenzoic acid, whereas the calcium channel blocker, lanthanum, had little effect. Because the onset of the gravity-induced current asymmetry coincided both spatially and temporally with the onset of the differential growth response, we suggest that this current efflux may result from auxin-requiring acid-growth phenomena in the upper root tissue. The implications of this simultaneous onset of both proton efflux and elongation for theories about gravity stimulus transduction are discussed.Studies of root gravitropism have focused on assessing the first stages of gravity perception by the sensing tissue (thought to be the columella cells in the root cap) and determining steps in the response that immediately precede discernible growth asymmetries in the elongation zone (8 and refs. therein). Recently, there has been considerable attention given to changes in root electrophysiology following gravity stimulation (4,5,19). The growing root tip is electrically active, and when it is placed in a conducting solution, ionic currents, measurable with the vibrating probe (14), typically enter the meristem and younger parts of the elongation zone and leave the remainder of the elongation zone and the more mature parts of the root (29).A gravitropic stimulus modifies the symmetrical current pattern found around the vertical root. Behrens et al. (4) measured changes in current parallel to the upper surface of Lepidium sativum roots. These changes were interpreted as

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Section: Gravistimulated Rootmentioning

confidence: 77%

Ionic Current Changes Associated with the Gravity-Induced Bending Response in Roots of Zea mays L.

Collings¹,

White²,

Overall³

1992

Plant Physiol.

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“…0n3 of stem length from the base, by which time the apex angle has reached 90m. Barlow & Rathfelder (1985), measuring the distribution of elemental growing rates along bending maize root, observed the bell-shape distribution, but concluded, that the peak of the curvature remained stationary during this gravitropic reaction. Computer-generated root images, based on this assumption, were considered to be realistic (Barlow, Brain & Adam, 1989).…”

Section: Local Curvature As a Two-parameter Function Of Position And mentioning

confidence: 99%

Mathematical modelling of morphogenesis in fungi: spatial organization of the gravitropic response in the mushroom stem of Coprinus cinereus

1998

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The purpose of this work was to establish how the distribution of local curvatures changed during the mushroom stem gravitropic reaction and to suggest a suitable mathematical model based on these new data.The gravitropic bending of base-and apex-pinned Coprinus cinereus (Fries) S. F. Gray stems was recorded on videotapes. The images were captured from the tapes after each 10 min, rotated by 45m and transformed into tables of changing co-ordinates of points for each stem. The non-linear regression of these points was performed using Legendre polynomials. From the resulting equations the patterns of changing local curvature for 50 subsections per stem during 400 min of gravitropic reaction were calculated.It was observed that base-pinned stems first bent from the apex, but later the curvature of this part decreased, and in the late stages the apex became nearly completely straight again. Subsections, located about one third of stem length from the base determined the main part of the final curvature. The free basal part of the apex-pinned stems bent upward and after a certain bending time also began to straighten. However, this process started significantly later and was weaker. Bending of the subsections close to the pinned apex did not stop when they reached the vertical position, and the final angle of gravitropic curvature could exceed 180m.Plotting various functions of local bending speed and its derivatives against each other and against local angle indicated that, if the hypothetical signal about reorientation arises in the apex, its propagation towards the base did not follow simple wave or simple diffusion laws. The importance of the local angle of all subsections both for signal origin and transmission was established and a signal transmission equation, involving local angle of each subsection, was derived. After creating a suitable program this partial differential equation was solved numerically. The generated shapes of the bending stem coincided in high degree with experimentally observed images.

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“…La réaction gravitropique peut se réaliser par un des mécanismes suivants : 1 · inhibition différentielle de la croissance des faces supérieures et inférieure des racines placées en position horizontale, la croissance de la face racinaire supérieure étant moins inhibihée que celle de la face inférieure (Konings, 1964 ;Perbal, 1973 ;Pilet et Ney, 1981 ;Nelson et Evans, 1986) ; 2 -stimulation de l'élongation de la face supérieure des racines orientées horizontalement et par inhibition de l'élongation de la face racinaire inférieure (Pilet et Ney, 1981 ;Barlow et Rathfelder, 1985) ; 3 ·stimulation de la croissance de la face supérieure des racines en position horizontale, sans modification de comportement de la face racinaire inférieure (Keeble et coll., 1931 ;Veen, 1964;Darbelley et coll., 1986 b).…”

Section: Introductionunclassified

Effets de la stimulation gravitropique et de la microgravité sur la prolifération et la différenciation cellulaires dans les racines primaires

Darbelley¹

1988

Bulletin de la Société Botanique de France. Lettres Botaniques

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Résumé.-Lorsque les racines de Lentille (Lens culinaris L., variété large blonde} sont gravistimulées en position horizontale durant 2h, les cellules corticales s'allongent plus rapidement dans la moitié supérieure que dans la moitié inférieure de la zone de courbure. La zone de graviréaction s'étend dans le méristème sensu stricto et dans la partie proximale de la zone d'élongation cellulaire.Dans le méristème, la courbure gravitropique se réalise par stimulation de l'élongation des cellules de la moitié supérieure. Dans la zone d'élongation cellulaire, la courbure est dûe à une inhibition de l'allongement des cellules de la moitié inférieure. L'analyse semi-quantitative de l'ultrastructure des cellules graviréactives révèle que la différenciation des organites est modifiée et que les modifications les plus remarquables concernent les cellules graviréactives méristématiques.La graviréaction entraîne une augmentation de l'activité mitotique dans l'ensemble de la ré-gion proximale et dans la moitié inférieure de la région distale de la zone méristématique. De plus, la gravistimulation provoque une augmentation des synthèses d'ADN nucléaire des cellules corticales dans la moitié supérieure de la région méristématique distale. Le cycle des cellules corticales est donc modifié lors de la cÔurbure gravitropique. Il est proposé que l'inhibiteur de croissance, responsable de la graviréaction racinaire, est un inhibiteur de la différenciation cellulaire et qu'un autre facteur hormonal, favorisant l'entrée en mitose, serait impliqué dans la réponse gravitropique.Dans les racines du Zea mays, dont la croissance s'est effectuée à bord du satellite COSMOS 1667, l'activité de prolifération des cellules corticales est plus intense et leur différenciation est plus rapide que dans les contrôles terrestres. Ces phénomènes sont comparés à ceux observés dans la réac-tion gravitropique de la racine de Lentille.Summary.-When lentil roots (Lens culinaris L., cv. large blonde} are gravistimulated in horizontal position for 2h, the length of the cortical cells is greater in the upper than in the lower hait of the zone of the gravitropic curvature. The bending begins in the meristem sensu stricto and is exten· ded to the proximal part of the cell elongation zone. ln the meristem, the curvature is due to astimulation of cell elongation in its upper half. ln the proximal part of the cell elongation zone, the curvature results from an inhibition of cell growth in its lower half. The semi-quantitative analyse of the ultrastructure of the gravireacting cells shows that the differentiation of organelles is changed during the gravireaction and the modifications are the greatest for the gravireacting meristematic ce lis.The gravireaction leads to an increase of the mitotic activity in the whole proximal part of the meristematic zone and also in the lower half of its distal part. Moreover, the gravistimulation brings about an increase of nuclear DNA synthesis of cortical cells in the upper half of the distal part of the meristematic zone. The ce...

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Distribution and redistribution of extension growth along vertical and horizontal gravireacting maize roots

Cited by 61 publications

References 17 publications

Ionic Current Changes Associated with the Gravity-Induced Bending Response in Roots of Zea mays L.

Ionic Current Changes Associated with the Gravity-Induced Bending Response in Roots of Zea mays L.

Mathematical modelling of morphogenesis in fungi: spatial organization of the gravitropic response in the mushroom stem of Coprinus cinereus

Effets de la stimulation gravitropique et de la microgravité sur la prolifération et la différenciation cellulaires dans les racines primaires

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