Specialized Zones of Development in Roots

Ishikawa, Hideo; Evans, Michael L.

doi:10.1104/pp.109.3.725

Cited by 169 publications

(133 citation statements)

References 7 publications

(9 reference statements)

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“…The length of this region thus represents about 5.5% of the entire growth zone. Subsequent studies confirmed the uniqueness of the cells located in the PIG zone, not only from a morphometrical point of view, but also on account of their specific cytological and physiological properties (Barlow et al, 1991;BaluSka et al, l992,1994BaluSka et al, l992, ,1996aBaluSka et al, l992, , 1996cIshikawa and Evans, 1992, 1993, 1995.…”

mentioning

confidence: 73%

“…Recently, Ishikawa and Evans (1995) focused attention on the immediately postmitotic growth zone of plant roots and indicated its importance in root growth in response to interna1 and externa1 factors. This previously unrecognized region of the root, intercalated between the apical meristem and the zone of rapid cell elongation, was originally discovered as the result of a morphometric analysis of the breadthlength ratios of cells along the length of the maize root (BaluSka et al, 1990).…”

mentioning

confidence: 99%

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Specialized Zones of Development in Roots: View from the Cellular Level

Baluška¹,

Volkmann²,

Barlow³

1996

Plant Physiology

132

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mentioning

confidence: 73%

mentioning

confidence: 99%

Specialized Zones of Development in Roots: View from the Cellular Level

Baluška¹,

Volkmann²,

Barlow³

1996

Plant Physiology

132

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“…Circadian effects on gene expression were taken into account by always germinating and harvesting roots of the same length at the same time of the day (germination, 6 PM; harvest, 10 AM). This sampling strategy was chosen because in maize, lateral roots are initiated in the differentiation zone (Ishikawa and Evans, 1995), although the site of lateral root formation in this zone cannot be predicted (Bell and McCully, 1970). Since elongation and differentiation zones in maize are partly overlapping, only pericycle cells from these two zones were collected.…”

Section: Pericycle-specific Transcriptome Profilingmentioning

confidence: 99%

“…Polar auxin transport was determined in 2-cm-long proximal fragments of the primary root (3 DAG) excluding at least 0.4 cm of the root tip, which contains the meristematic and distal elongation zone (Ishikawa and Evans, 1995), and in 1-cm fragments of the basal part of the coleoptile (5 DAG) after removing at least 0.3 cm of the coleoptile tip in paper rolls at 28°C in the dark. Only seedlings with a primary root length of about 2.5 cm were used for the experiments.…”

Section: Measurement Of Auxin Transportmentioning

confidence: 99%

Isolation, Characterization, and Pericycle-Specific Transcriptome Analyses of the Novel Maize Lateral and Seminal Root Initiation Mutant rum1

Woll

Borsuk²,

Stransky³

et al. 2005

Plant Physiology

179

190

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The monogenic recessive maize (Zea mays) mutant rootless with undetectable meristems 1 (rum1) is deficient in the initiation of the embryonic seminal roots and the postembryonic lateral roots at the primary root. Lateral root initiation at the shoot-borne roots and development of the aerial parts of the mutant rum1 are not affected. The mutant rum1 displays severely reduced auxin transport in the primary root and a delayed gravitropic response. Exogenously applied auxin does not induce lateral roots in the primary root of rum1. Lateral roots are initiated in a specific cell type, the pericycle. Cell-type-specific transcriptome profiling of the primary root pericycle 64 h after germination, thus before lateral root initiation, via a combination of laser capture microdissection and subsequent microarray analyses of 12k maize microarray chips revealed 90 genes preferentially expressed in the wild-type pericycle and 73 genes preferentially expressed in the rum1 pericycle (fold change .2; P-value ,0.01; estimated false discovery rate of 13.8%). Among the 51 annotated genes predominately expressed in the wild-type pericycle, 19 genes are involved in signal transduction, transcription, and the cell cycle. This analysis defines an array of genes that is active before lateral root initiation and will contribute to the identification of checkpoints involved in lateral root formation downstream of rum1.

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“…Supportive evidence for an auxin asymmetry in the EZ after gravistimulation has come from the analyses of radio-labeled auxin distribution, or differential induction of auxin-response promoters (4). It has been questioned, however, whether auxin gradients are necessary or sufficient to cause root gravitropism (3,5). Furthermore, it is not clear as to how the gravisensing events in the columella cells can give rise to changes in auxin concentration in the EZ.…”

mentioning

confidence: 99%

Gravity-regulated differential auxin transport from columella to lateral root cap cells

Ottenschläger

Wolff

Wolverton

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

497

387

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Gravity-induced root curvature has long been considered to be regulated by differential distribution of the plant hormone auxin. However, the cells establishing these gradients, and the transport mechanisms involved, remain to be identified. Here, we describe a GFP-based auxin biosensor to monitor auxin during Arabidopsis root gravitropism at cellular resolution. We identify elevated auxin levels at the root apex in columella cells, the site of gravity perception, and an asymmetric auxin flux from these cells to the lateral root cap (LRC) and toward the elongation zone after gravistimulation. We differentiate between an efflux-dependent lateral auxin transport from columella to LRC cells, and an effluxand influx-dependent basipetal transport from the LRC to the elongation zone. We further demonstrate that endogenous gravitropic auxin gradients develop even in the presence of an exogenous source of auxin. Live-cell auxin imaging provides unprecedented insights into gravity-regulated auxin flux at cellular resolution, and strongly suggests that this flux is a prerequisite for root gravitropism.gravitropic root curvature ͉ polar auxin transport ͉ auxin carrier proteins G ravity plays a major role in plant morphogenesis by determining the directional growth of plant organs (gravitropism). Roots orient at a preferred angle with respect to gravity [their gravitropic set-point angle (GSA); ref. 1], allowing efficient exploration of the soil (root gravitropism). Main roots of Arabidopsis seedlings, for instance, have a GSA of 0°and grow parallel to the gravity vector. Changes in gravity vector orientation (gravistimulation) induce root curvature, resulting in realignment of the root tip to the GSA. Root curvature is a consequence of gravity signal perception, involving amyloplast sedimentation in the columella cells of the root cap (2), and differential growth induced on opposite flanks in the elongation zone (EZ). In the 1920s, the Cholodny-Went hypothesis and various interpretations of it ever since have proposed that this differential growth within the EZ is mediated by an asymmetric distribution of the plant hormone auxin (3). Supportive evidence for an auxin asymmetry in the EZ after gravistimulation has come from the analyses of radio-labeled auxin distribution, or differential induction of auxin-response promoters (4). It has been questioned, however, whether auxin gradients are necessary or sufficient to cause root gravitropism (3, 5). Furthermore, it is not clear as to how the gravisensing events in the columella cells can give rise to changes in auxin concentration in the EZ. Recently, the gravity-dependent relocation of an auxin efflux carrier protein in columella cells suggested gravity-regulated changes of auxin transport right at the site of gravity perception in the root cap (6). However, differential auxin fluxes through the cap cells and their contribution to gravitropic root curvature remain to be demonstrated. In the work presented here, we applied a GFP-based auxin biosensor to study gravity-induced ...

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Specialized Zones of Development in Roots

Cited by 169 publications

References 7 publications

Specialized Zones of Development in Roots: View from the Cellular Level

Specialized Zones of Development in Roots: View from the Cellular Level

Isolation, Characterization, and Pericycle-Specific Transcriptome Analyses of the Novel Maize Lateral and Seminal Root Initiation Mutant rum1

Gravity-regulated differential auxin transport from columella to lateral root cap cells

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