scholarly journals Cytoskeleton dynamics control early events of lateral root initiation in Arabidopsis

2019 ◽  
Author(s):  
Amaya Vilches Barro ◽  
Dorothee Stöckle ◽  
Martha Thellmann ◽  
Paola Ruiz-Duarte ◽  
Lotte Bald ◽  
...  
Keyword(s):  
Lateral Root ◽  
Lateral Roots ◽  
Asymmetric Division ◽  
List Type ◽  
Radial Expansion ◽  
Cellular Mechanisms ◽  
Differential Growth ◽  
Auxin Signalling ◽  
Genetic Perturbations ◽  
Founder Cells

SUMMARYHow plant cells re-establish differential growth to initiate organs is poorly understood. Morphogenesis of lateral roots relies on the tightly controlled radial expansion and asymmetric division of founder cells. The cellular mechanisms that license and ensure these features are unknown. Here, we quantitatively analyse F-actin and microtubule dynamics during LR initiation. Using mutants, pharmacological and tissue-specific genetic perturbations, we show that dynamic reorganisation of both microtubule and F-actin networks is required for the asymmetric expansion of the founder cells. This cytoskeleton remodelling intertwine with auxin signalling in the pericycle and endodermis in order for founder cells to acquire a basic polarity required for initiating LR development. Our results reveal the conservation of cell remodelling and polarisation strategies between the Arabidopsis zygote and lateral root founder cells. We propose that coordinated, auxin-driven reorganisation of the cytoskeleton licenses asymmetric cell growth and divisions during embryonic and post-embryonic organogenesis.HIGHLIGHTSFailure for lateral root founder cells to undergo asymmetric radial expansion before division, leads to aberrant organ formation.Cortical microtubules arrays reorganise to facilitate this asymmetric expansion and F-actin the asymmetric division.Cytoskeletal reorganisation depends on auxin signalling.New genetic tools allow to perturb microtubules or actin in an inducible and cell-type specific manner.

scholarly journals Clonal analysis reveals gradual recruitment of lateral root founder cells and a link between root initiation and cambium formation in Arabidopsis thaliana

2018 ◽  
Author(s):  
Joseph G. Dubrovsky
Keyword(s):  
Lateral Roots ◽  
Cell Activity ◽  
Cell Lineage ◽  
Clonal Analysis ◽  
List Type ◽  
Differentiation Zone ◽  
Pericycle Cell ◽  
Cell Clones ◽  
Gradual Process ◽  
Founder Cells

AbstractThe pericycle gives rise to lateral roots (LRs) and lateral meristems (LMs; cambium and phellogen), however, a thorough clonal analysis of pericycle cell lineage has not been investigated. This study fills in this gap and addresses pericycle impact in LR and LM development.Heath-shock inducible DS1 transposition in 35S-DS1-H2B:YFP; HS-Ac seedlings results in production of YFP-labelled cell clones. These clones in pericycle cell derivatives were identified with a confocal microscopy and subjected to 3D reconstructions and analysis.Participation of pericycle founder cells (FC) in LR formation is more variable than previously considered. LR initiation was found most commonly involved the specification of just one FC in the longitudinal and one or two cells in transverse direction. After LR initiation, FCs continue to be recruited in both directions from pre-existing cells. Anticlinal divisions in the pericycle resulting in LMs start already in the young differentiation zone where only the protoxylem is differentiated.The clonal analysis demonstrated that pericycle cell activity related to LR formation is not separated in time and space from that related to LM formation and that LR FC recruitment is a gradual process. The analysis demonstrated that immediate pericycle progeny lack self-renewal capacity.

Lateral root formation and nutrients: nitrogen in the spotlight

2021 ◽  
Author(s):  
Pierre-Mathieu Pélissier ◽  
Hans Motte ◽  
Tom Beeckman
Keyword(s):  
Signaling Pathways ◽  
Root System ◽  
Root Development ◽  
Lateral Root ◽  
Molecular Mechanisms ◽  
Root Formation ◽  
Lateral Roots ◽  
Nutrient Use Efficiency ◽  
Lateral Root Formation ◽  
Lateral Root Development

Abstract Lateral roots are important to forage for nutrients due to their ability to increase the uptake area of a root system. Hence, it comes as no surprise that lateral root formation is affected by nutrients or nutrient starvation, and as such contributes to the root system plasticity. Understanding the molecular mechanisms regulating root adaptation dynamics towards nutrient availability is useful to optimize plant nutrient use efficiency. There is at present a profound, though still evolving, knowledge on lateral root pathways. Here, we aimed to review the intersection with nutrient signaling pathways to give an update on the regulation of lateral root development by nutrients, with a particular focus on nitrogen. Remarkably, it is for most nutrients not clear how lateral root formation is controlled. Only for nitrogen, one of the most dominant nutrients in the control of lateral root formation, the crosstalk with multiple key signals determining lateral root development is clearly shown. In this update, we first present a general overview of the current knowledge of how nutrients affect lateral root formation, followed by a deeper discussion on how nitrogen signaling pathways act on different lateral root-mediating mechanisms for which multiple recent studies yield insights.

TMK1-mediated auxin signalling regulates differential growth of the apical hook

Nature ◽  
2019 ◽  
Vol 568 (7751) ◽  
pp. 240-243 ◽  
Author(s):  
Min Cao ◽  
Rong Chen ◽  
Pan Li ◽  
Yongqiang Yu ◽  
Rui Zheng ◽  
...  
Keyword(s):  
Differential Growth ◽  
Apical Hook ◽  
Auxin Signalling

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 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.

scholarly journals Influence of Root Morphology on Ecological Slope Protection

2020 ◽  
Vol 198 ◽  
pp. 04036
Author(s):  
JI Xiaolei ◽  
XU Lanlan ◽  
YANG Guoping
Keyword(s):  
Root Morphology ◽  
Lateral Root ◽  
Lateral Roots ◽  
Soil Mass ◽  
Soil Reinforcement ◽  
Main Root ◽  
Protection Effect ◽  
Included Angle ◽  
Theoretical Support ◽  
Object Based

Ecological slope protection is of great importance for preventing the water and soil loss on bare slopes, improving the ecological environment, and realizing the sustainable ecosystem development. The root-soil composite slope consisting of homogenous soil mass and oleander root system was taken as the study object. Based on the mechanics principle of soil reinforcement by roots in ecological slope protection, the influences of the lateral root quantity of plants and included angle between main root and lateral root on the slope protection were investigated via the finite element (FE) software ABAQUS. The simulation results show that the larger the quantity of lateral roots, the more obvious the displacement reduction of the soil mass on the slope surface will be. The slope protection effect varies with the root morphology, the included angle between main root and lateral root is an important factor influencing the slope protection effect of plants, and the slope protection effect at included angle of 30° is apparently superior to that at 90°. The research results can provide a theoretical support for the plant selection in the ecological slope protection.

Lateral root initiation in Marsilea quadrifolia. I. Origin and histogenesis of lateral roots

1991 ◽  
Vol 69 (1) ◽  
pp. 123-135 ◽  
Author(s):  
Bai-Ling Lin ◽  
V. Raghavan
Keyword(s):  
Lateral Root ◽  
Single Cells ◽  
Lateral Roots ◽  
Central Axis ◽  
Root Initiation ◽  
Vascular Connection ◽  
Lateral Root Initiation ◽  
Marsilea Quadrifolia ◽  
Lateral Root Primordium ◽  
Root Primordium

In Marsilea quadrifolia, lateral roots arise from modified single cells of the endodermis located opposite the protoxylem poles within the meristematic region of the parent root. The initial cell divides in four specific planes to establish a fivecelled lateral root primordium, with a tetrahedral apical cell in the centre and the oldest merophytes and the root cap along the sides. The cells of the merophyte divide in a precise pattern to give rise to the cells of the cortex, endodermis, pericycle, and vascular tissues of the emerging lateral root. Although the construction of the parent root is more complicated than that of lateral roots, patterns of cell division and tissue formation are similar in both types of roots, with the various tissues being arranged in similar positions in relation to the central axis. Vascular connection between the lateral root primordium and the parent root is derived from the pericycle cells lying between the former and the protoxylem members of the latter. It is proposed that the central axis of the root is not only a geometric centre, but also a physiological centre which determines the fate of the different cell types. Key words: lateral root initiation, Marsilea quadrifolia, root histogenesis.

The Activity of a Tobacco Basic Chitinase Promotor in Transgenic White Clover Provides Insights into Plant Development and Symbiosis

1997 ◽  
Vol 24 (5) ◽  
pp. 555 ◽  
Author(s):  
Christopher Pittock ◽  
Jeremy J. Weinman ◽  
Barry G. Rolfe
Keyword(s):  
White Clover ◽  
Lateral Root ◽  
Transgene Expression ◽  
Lateral Roots ◽  
Developmental Expression ◽  
Nodule Formation ◽  
Post Inoculation ◽  
Environmental Response ◽  
Root Epidermis ◽  
Root Meristems

White clover was transformed with a tobacco basic chitinase promoter:GUS fusion. Basic chitinase promoter activity was detected by histochemical staining. Comparison of the spatial and temporal expression of the chitinase promoter-driven GUS gene in tobacco to that in white clover indicates that transcription from the promoter is induced by similar developmental and environmental response programs in each species. Wound-responsiveness of the white clover transgene was rapid and localised following mechanical and aphid (Family Aphididae) wounding. Developmental expression of the transgene during root morphogenesis reveals strong expression in tap and lateral root meristems but expression in lateral root meristems was observed only after the emergence through the tap root epidermis. No expression of the transgene was detected in the pericycle or the dividing cells of the developing lateral root. The expression of the tobacco basic chitinase promoter:GUS transgene in white clover was then used as a marker to examine the differences between the early developmental pathways leading to lateral root formation and those involoved in nodule formation in response to Rhizobium inoculation. Inoculation of the zone of emerging root hairs with a nodulation-competent Rhizobium strain ANU845(pRI4003), triggered transient transgene expression 2 to 4 h post-inoculation. No transgene expression was detectable after inoculation with purified Nod factor from strain ANU843. Our results suggest that lateral roots and nodules differ both in some of the mechanisms required to initiate cell division, and in their ongoing development after the emergence from the root epidermis.

NaCl salinity affects lateral root development in Plantago maritima

2004 ◽  
Vol 31 (8) ◽  
pp. 775 ◽  
Author(s):  
Michael Rubinigg ◽  
Julia Wenisch ◽  
J. Theo M. Elzenga ◽  
Ineke Stulen
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Root Length ◽  
Lateral Root ◽  
Lateral Roots ◽  
Third Order ◽  
Lateral Root Primordia ◽  
Relative Growth ◽  
Length Growth ◽  
Lateral Root Length

Root growth and morphology were assessed weekly in hydroponically-grown seedlings of the halophyte Plantago maritima L. during exposure to 0, 50, 100 and 200 mm NaCl for 21 d. Relative growth rate was reduced by 25% at 200 mm NaCl. The lower NaCl treatments did not affect relative growth rates. Primary and lateral roots responded differently to NaCl. While primary-root length increased at all NaCl concentrations, total lateral-root length increased at 50 and was not affected at 100 mm but was considerably reduced at 200 mm NaCl. NaCl concentrations of 50 and 100 mm, which had no effect on relative growth rate or total lateral-root length, severely affected root branching pattern in that the number of first, second and third order laterals was reduced. At 200 mm NaCl third order laterals were not formed at all. However, mean lateral-root length was increased at all NaCl concentrations and was highest at 200 mm NaCl. We conclude that the increase in total lateral-root length in plants at 50 and 100 mm NaCl was mainly caused by increased length growth, while the decrease in total lateral-root length at 200 mm was the consequence of inhibition of lateral root primordia and / or the activation of apical meristems rather than reduced length growth.

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