Lateral root initiation by asymmetrical transverse divisions of pericycle cells in adventitious roots ofAllium cepa

PROTOPLASMA ◽  
1993 ◽  
Vol 176 (3-4) ◽  
pp. 138-144 ◽  
Author(s):  
P. J. Casero ◽  
I. Casimiro ◽  
L. Rodr�guez-Gallardo ◽  
G. Mart�n-Partido ◽  
P. G. Lloret
Keyword(s):  
Lateral Root ◽  
Adventitious Roots ◽  
Root Initiation ◽  
Lateral Root Initiation ◽  
Ofallium Cepa ◽  
Pericycle Cells

Pericycle proliferation pattern during the lateral root initiation in adventitious roots ofAllium cepa

PROTOPLASMA ◽  
1996 ◽  
Vol 191 (3-4) ◽  
pp. 136-147 ◽  
Author(s):  
P. J. Casero ◽  
I. Casimiro ◽  
P. G. Lloret
Keyword(s):  
Lateral Root ◽  
Adventitious Roots ◽  
Root Initiation ◽  
Lateral Root Initiation ◽  
Ofallium Cepa

Formation of lateral root meristems is a two-stage process

Development ◽  
1995 ◽  
Vol 121 (10) ◽  
pp. 3303-3310 ◽  
Author(s):  
M.J. Laskowski ◽  
M.E. Williams ◽  
H.C. Nusbaum ◽  
I.M. Sussex
Keyword(s):  
Lateral Root ◽  
Lateral Roots ◽  
Initial Period ◽  
Subsequent Stage ◽  
Root Initiation ◽  
Root Meristems ◽  
Lateral Root Initiation ◽  
Cell Layers ◽  
Stage Process ◽  
Pericycle Cells

In both radish and Arabidopsis, lateral root initiation involves a series of rapid divisions in pericycle cells located on the xylem radius of the root. In Arabidopsis, the number of pericycle cells that divide to form a primordium was estimated to be about 11. To determine the stage at which primordia are able to function as root meristems, primordia of different stages were excised and cultured without added hormones. Under these conditions, primordia that consist of 2 cell layers fail to develop while primordia that consist of at least 3–5 cell layers develop as lateral roots. We hypothesize that meristem formation is a two-step process involving an initial period during which a population of rapidly dividing, approximately isodiametric cells that constitutes the primordium is formed, and a subsequent stage during which meristem organization takes place within the primordium.

scholarly journals EXPANSIN A1-mediated radial swelling of pericycle cells positions anticlinal cell divisions during lateral root initiation

2019 ◽  
Vol 116 (17) ◽  
pp. 8597-8602 ◽  
Author(s):  
Priya Ramakrishna ◽  
Paola Ruiz Duarte ◽  
Graham A. Rance ◽  
Martin Schubert ◽  
Vera Vordermaier ◽  
...  
Keyword(s):  
Lateral Root ◽  
Asymmetric Cell Division ◽  
Lateral Roots ◽  
Root Initiation ◽  
Asymmetric Cell Divisions ◽  
Cell Divisions ◽  
Lateral Root Initiation ◽  
Root Organogenesis ◽  
A Cell ◽  
Pericycle Cells

In plants, postembryonic formation of new organs helps shape the adult organism. This requires the tight regulation of when and where a new organ is formed and a coordination of the underlying cell divisions. To build a root system, new lateral roots are continuously developing, and this process requires the tight coordination of asymmetric cell division in adjacent pericycle cells. We identified EXPANSIN A1 (EXPA1) as a cell wall modifying enzyme controlling the divisions marking lateral root initiation. Loss ofEXPA1leads to defects in the first asymmetric pericycle cell divisions and the radial swelling of the pericycle during auxin-driven lateral root formation. We conclude that a localized radial expansion of adjacent pericycle cells is required to position the asymmetric cell divisions and generate a core of small daughter cells, which is a prerequisite for lateral root organogenesis.

scholarly journals Phloem-associated auxin response maxima determine radial positioning of lateral roots in maize

2012 ◽  
Vol 367 (1595) ◽  
pp. 1525-1533 ◽  
Author(s):  
Leentje Jansen ◽  
Ianto Roberts ◽  
Riet De Rycke ◽  
Tom Beeckman
Keyword(s):  
Lateral Root ◽  
Vascular Tissue ◽  
Lateral Roots ◽  
Root Tip ◽  
Root Initiation ◽  
Auxin Response ◽  
Lateral Root Initiation ◽  
Evolutionarily Conserved ◽  
Chemical Inhibition ◽  
Pericycle Cells

In Arabidopsis thaliana , lateral-root-forming competence of pericycle cells is associated with their position at the xylem poles and depends on the establishment of protoxylem-localized auxin response maxima. In maize, our histological analyses revealed an interruption of the pericycle at the xylem poles, and confirmed the earlier reported proto-phloem-specific lateral root initiation. Phloem-pole pericycle cells were larger and had thinner cell walls compared with the other pericycle cells, highlighting the heterogeneous character of the maize root pericycle. A maize DR5::RFP marker line demonstrated the presence of auxin response maxima in differentiating xylem cells at the root tip and in cells surrounding the proto-phloem vessels. Chemical inhibition of auxin transport indicated that the establishment of the phloem-localized auxin response maxima is crucial for lateral root formation in maize, because in their absence, random divisions of pericycle and endodermis cells occurred, not resulting in organogenesis. These data hint at an evolutionarily conserved mechanism, in which the establishment of vascular auxin response maxima is required to trigger cells in the flanking outer tissue layer for lateral root initiation. It further indicates that lateral root initiation is not dependent on cellular specification or differentiation of the type of vascular tissue.

scholarly journals Interacting Glutamate Receptor-Like Proteins in Phloem Regulate Lateral Root Initiation in Arabidopsis

2013 ◽  
Vol 25 (4) ◽  
pp. 1304-1313 ◽  
Author(s):  
Eric D. Vincill ◽  
Arielle E. Clarin ◽  
Jennifer N. Molenda ◽  
Edgar P. Spalding
Keyword(s):  
Glutamate Receptor ◽  
Lateral Root ◽  
Root Initiation ◽  
Lateral Root Initiation

scholarly journals Auxin minimum defines a developmental window for lateral root initiation

2011 ◽  
Vol 191 (4) ◽  
pp. 970-983 ◽  
Author(s):  
Joseph G. Dubrovsky ◽  
Selene Napsucialy-Mendivil ◽  
Jérme Duclercq ◽  
Yan Cheng ◽  
Svetlana Shishkova ◽  
...  
Keyword(s):  
Lateral Root ◽  
Root Initiation ◽  
Lateral Root Initiation ◽  
Developmental Window

scholarly journals AT-HOOK MOTIF NUCLEAR LOCALISED PROTEIN 18 as a Novel Modulator of Root System Architecture

2020 ◽  
Author(s):  
Marek Šírl ◽  
Tereza Šnajdrová ◽  
Dolores Gutiérrez-Alanís ◽  
Joseph G. Dubrovsky ◽  
Jean Phillipe Vielle-Calzada ◽  
...  
Keyword(s):  
Root System ◽  
System Architecture ◽  
Lateral Root ◽  
Apical Meristem ◽  
Lateral Roots ◽  
Primary Root ◽  
Root System Architecture ◽  
Root Apical Meristem ◽  
Root Initiation ◽  
Lateral Root Initiation

The AT-HOOK MOTIF NUCLEAR LOCALIZED PROTEIN (AHL) gene family encodes embryophyte-specific nuclear proteins with DNA binding activity. They modulate gene expression and affect various developmental processes in plants. We identify AHL18 (At3G60870) as a developmental modulator of root system architecture and growth. AHL18 regulates the length of the proliferation domain and number of dividing cells in the root apical meristem and thereby, cell production. Both primary root growth and lateral root development respond according to AHL18 transcription level. The ahl18 knock-out plants show reduced root systems due to a shorter primary root and a lower number of lateral roots. This change results from a higher number of arrested and non-developing lateral root primordia (LRP) rather than from decreased initiation. Overexpression of AHL18 results in a more extensive root system, longer primary roots, and increased density of lateral root initiation events. Formation of lateral roots is affected during the initiation of LRP and later development. AHL18 regulate root apical meristem activity, lateral root initiation and emergence, which is in accord with localization of its expression.

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