scholarly journals Tornado1 and tornado2 are required for the specification of radial and circumferential pattern in the Arabidopsis root

Development ◽  
2000 ◽  
Vol 127 (15) ◽  
pp. 3385-3394
Author(s):  
G. Cnops ◽  
X. Wang ◽  
P. Linstead ◽  
M. Van Montagu ◽  
M. Van Lijsebettens ◽  
...  
Keyword(s):  
Root Hair ◽  
Lateral Root ◽  
Cell Function ◽  
Primary Root ◽  
Root Cap ◽  
Radial Pattern ◽  
Root Hair Cell ◽  
Cell Layers ◽  
Default State ◽  
Hair Cell Differentiation

The cell layers of the Arabidopsis primary root are arranged in a simple radial pattern. The outermost layer is the lateral root cap and lies outside the epidermis that surrounds the ground tissue. The files of epidermal and lateral root cap cells converge on a ring of initials (lateral root cap/epidermis initial) from which the epidermal and lateral root cap tissues of the seedling are derived, once root growth is initiated after germination. Each initial gives rise to a clone of epidermal cells and a clone of lateral root cap cells. These initial divisions in the epidermal/lateral root cap initial are defective in tornado1 (trn1) and trn2 plants indicating a requirement for TRN1 and TRN2 for initial cell function. Furthermore, lateral root cap cells develop in the epidermal position in trn1 and trn2 roots indicating that TRN1 and TRN2 are required for the maintenance of the radial pattern of cell specification in the root. The death of these ectopic lateral root cap cells in the elongation zone (where lateral root cap cells normally die) results in the development of gaps in the epidermis. These observations indicate that TRN1 and TRN2 are required to maintain the distinction between the lateral root cap and epidermis and suggest that lateral root cap fate is the default state. It also suggests that TRN1 and TRN2 repress lateral root cap fate in cells in the epidermal location. Furthermore, the position-dependent pattern of root hair and non-root hair cell differentiation in the epidermis is defective in trn1 and trn2 mutants. Together these results indicate that TRN1 and TRN2 are required for the maintenance of both the radial pattern of tissue differentiation in the root and for the subsequent circumferential pattern within the epidermis.

scholarly journals Deep Sequencing Reveals Early Reprogramming of Arabidopsis Root Transcriptomes Upon Ralstonia solanacearum Infection

2019 ◽  
Vol 32 (7) ◽  
pp. 813-827 ◽  
Author(s):  
Cuizhu Zhao ◽  
Huijuan Wang ◽  
Yao Lu ◽  
Jinxue Hu ◽  
Ling Qu ◽  
...  
Keyword(s):  
Differentially Expressed Genes ◽  
Root Hair ◽  
Ralstonia Solanacearum ◽  
Lateral Root ◽  
Molecular Mechanisms ◽  
Temporal Dynamics ◽  
Primary Root ◽  
Differentially Expressed ◽  
Root Growth Inhibition ◽  
Successful Infection

Bacterial wilt caused by the bacterial pathogen Ralstonia solanacearum is one of the most devastating crop diseases worldwide. The molecular mechanisms controlling the early stage of R. solanacearum colonization in the root remain unknown. Aiming to better understand the mechanism of the establishment of R. solanacearum infection in root, we established four stages in the early interaction of the pathogen with Arabidopsis roots and determined the transcriptional profiles of these stages of infection. A total 2,698 genes were identified as differentially expressed genes during the initial 96 h after infection, with the majority of changes in gene expression occurring after pathogen-triggered root-hair development observed. Further analysis of differentially expressed genes indicated sequential activation of multiple hormone signaling cascades, including abscisic acid (ABA), auxin, jasmonic acid, and ethylene. Simultaneous impairment of ABA receptor genes promoted plant wilting symptoms after R. solanacearum infection but did not affect primary root growth inhibition or root-hair and lateral root formation caused by R. solanacearum. This indicated that ABA signaling positively regulates root defense to R. solanacearum. Moreover, transcriptional changes of genes involved in primary root, lateral root, and root-hair formation exhibited high temporal dynamics upon infection. Taken together, our results suggest that successful infection of R. solanacearum on roots is a highly programmed process involving in hormone crosstalk.

scholarly journals Reactive oxygen species signalling is involved in alkamide-induced altered root development.

2021 ◽  
Author(s):  
Tonatiu Campos García ◽  
Jorge Molina-Torres ◽  
Kirk L Overmyer
Keyword(s):  
Root Hair ◽  
Lateral Root ◽  
Root Architecture ◽  
Primary Root ◽  
Heterotrimeric G Proteins ◽  
Reverse Genetic ◽  
Transcriptional Reprogramming ◽  
Protein Mutants ◽  
Induced Changes

Alkamides are alpha unsaturated N-acylamides structurally related to N-acyl ethanolamides (NAEs) and N-acyl-L-homoserine lactones (AHLs). Studies have shown that alkamides induce prominent changes in root architecture, a significant metabolic readjustment, and transcriptional reprogramming. Some alkamide responses have been associated with redox signalling; however, this involvement and ROS sources have not been fully described. We utilized a genetic approach to address ROS signalling in alkamide-induced processes and found that in Arabidopsis, treatment with the alkamide affinin (50μM) increased the in-situ accumulation of H2O2 in lateral root emergence sites and reduced H2O2 accumulation in primary root meristems implying that altered root growth was dependent on endogenous H2O2. Results show that ROS sourced from PRX34, RBOHC and RBOHD were involved in promotion of lateral root emergence by alkamides. RBOHC was required for affinin-induced enhanced root hair expansion. Furthermore, affinin-induced changes in lateral root emergence, but not root hair length, were dependent on a change in extracellular pH. Finally, reverse genetic experiments suggest heterotrimeric G-proteins were involved in plant response to alkamides; nevertheless, further studies with additional higher order G-protein mutants will be required to resolve this question. These results support that alkamides recruit specific ROS signaling programs to mediate alterations in root architecture.

scholarly journals The cap size and shape of Arabidopsis thaliana primary roots impact the root responses to an increase in medium strength

2018 ◽  
Author(s):  
J. Roué ◽  
H. Chauvet ◽  
N. Brunel-Michac ◽  
F. Bizet ◽  
B. Moulia ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Primary Root ◽  
Root Cap ◽  
Size And Shape ◽  
Primary Roots ◽  
Medium Strength ◽  
Cell Layers ◽  
Root Responses ◽  
Mutant Lines

AbstractDuring root progression in soil, root cap cells are the first to encounter obstacles. The root cap is known to sense environmental cues, making it a relevant candidate for a mechanosensing site. An original two-layer medium was developed in order to study root responses to growth medium strength and the importance of the root cap in the establishment of these responses. Root growth and trajectory of primary roots of Arabidopsis thaliana seedlings were investigated using in vivo image analysis. After contact with the harder layer, the root either penetrated it or underwent rapid curvature, enabling reorientation of the root primary growth. The role of the root cap in tip reorientation was investigated by analyzing the responses of Arabidopsis mutant roots with altered caps. The primary root of fez-2 mutant lines, which has fewer root cap cell layers than wild-type roots, showed impaired penetration ability. Conversely, smb-3 roots of mutant lines, which display a higher number of root cap cells, showed enhanced penetration abilities. This work highlights that alterations in root cap shape and size affect the root responses to medium strength.HighlightThe analysis of the growth and orientation of Arabidopsis thaliana mutant roots affected in root cap size and shape showed that properly formed root cap is required to trigger the root responses to medium strength.AbbreviationsCOLcolumella;LRCLateral Root Cap;SISharpness Index;SMBSOMBRERO.

scholarly journals Bacillus megaterium Rhizobacteria Promote Growth and Alter Root-System Architecture Through an Auxin- and Ethylene-Independent Signaling Mechanism in Arabidopsis thaliana

2007 ◽  
Vol 20 (2) ◽  
pp. 207-217 ◽  
Author(s):  
José López-Bucio ◽  
Juan Carlos Campos-Cuevas ◽  
Erasto Hernández-Calderón ◽  
Crisanto Velásquez-Becerra ◽  
Rodolfo Farías-Rodríguez ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Root Growth ◽  
Root Hair ◽  
Lateral Root ◽  
Root Formation ◽  
Growth Promotion ◽  
Primary Root ◽  
Root System Architecture ◽  
Ethylene Signaling ◽  
Primary Root Growth

Soil microorganisms are critical players in plant-soil interactions at the rhizosphere. We have identified a Bacillus megaterium strain that promoted growth and development of bean (Phaseolus vulgaris) and Arabidopsis thaliana plants. We used Arabidopsis thaliana as a model to characterize the effects of inoculation with B. megaterium on plant-growth promotion and postembryonic root development. B. megaterium inoculation caused an inhibition in primary-root growth followed by an increase in lateral-root number, lateral-root growth, and root-hair length. Detailed cellular analyses revealed that primary root-growth inhibition was caused both by a reduction in cell elongation and by reduction of cell proliferation in the root meristem. To study the contribution of auxin and ethylene signaling pathways in the alterations in root-system architecture elicited by B. megaterium, a suite of plant hormone mutants of Arabidopsis, including aux1-7, axr4-1, eir1, etr1, ein2, and rhd6, defective in either auxin or ethylene signaling, were evaluated for their responses to inoculation with this bacteria. When inoculated, all mutant lines tested showed increased biomass production. Moreover, aux1-7 and eir1, which sustain limited root-hair and lateral-root formation when grown in uninoculated medium, were found to increase the number of lateral roots and to develop long root hairs when inoculated with B. megaterium. The ethylene-signaling mutants etr1 and ein2 showed an induction in lateral-root formation and root-hair growth in response to bacterial inoculation. Taken together, our results suggest that plant-growth promotion and root-architectural alterations by B. megaterium may involve auxin- and-ethylene independent mechanisms.

Arabidopsis thaliana Root Hair Cell Cytoplasmic pH (pHc) Imaging

BIO-PROTOCOL ◽  
2015 ◽  
Vol 5 (7) ◽  
Author(s):  
Ling Bai ◽  
Yun Zhou ◽  
Pengtao Wang ◽  
Chun-Peng Song
Keyword(s):  
Arabidopsis Thaliana ◽  
Hair Cell ◽  
Root Hair ◽  
Cytoplasmic Ph ◽  
Root Hair Cell

scholarly journals High throughput phenotyping of root growth dynamics, lateral root formation, root architecture and root hair development enabled by PlaRoM

2009 ◽  
Vol 36 (11) ◽  
pp. 938 ◽  
Author(s):  
Nima Yazdanbakhsh ◽  
Joachim Fisahn
Keyword(s):  
Root Growth ◽  
Growth Kinetics ◽  
Lateral Root ◽  
Root Architecture ◽  
Imaging Techniques ◽  
Plant Root ◽  
Primary Root ◽  
Growth Media ◽  
Root Extension ◽  
Lateral Root Development

Plant organ phenotyping by non-invasive video imaging techniques provides a powerful tool to assess physiological traits and biomass production. We describe here a range of applications of a recently developed plant root monitoring platform (PlaRoM). PlaRoM consists of an imaging platform and a root extension profiling software application. This platform has been developed for multi parallel recordings of root growth phenotypes of up to 50 individual seedlings over several days, with high spatial and temporal resolution. PlaRoM can investigate root extension profiles of different genotypes in various growth conditions (e.g. light protocol, temperature, growth media). In particular, we present primary root growth kinetics that was collected over several days. Furthermore, addition of 0.01% sucrose to the growth medium provided sufficient carbohydrates to maintain reduced growth rates in extended nights. Further analysis of records obtained from the imaging platform revealed that lateral root development exhibits similar growth kinetics to the primary root, but that root hairs develop in a faster rate. The compatibility of PlaRoM with currently accessible software packages for studying root architecture will be discussed. We are aiming for a global application of our collected root images to analytical tools provided in remote locations.

scholarly journals The TOR–Auxin Connection Upstream of Root Hair Growth

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 150 ◽  
Author(s):  
Katarzyna Retzer ◽  
Wolfram Weckwerth
Keyword(s):  
Cell Fate ◽  
Root Hair ◽  
Hair Growth ◽  
Environmental Changes ◽  
Growth Control ◽  
Root Hairs ◽  
Signaling Cascades ◽  
Continuous Growth ◽  
Root Hair Cell ◽  
Root Hair Growth

Plant growth and productivity are orchestrated by a network of signaling cascades involved in balancing responses to perceived environmental changes with resource availability. Vascular plants are divided into the shoot, an aboveground organ where sugar is synthesized, and the underground located root. Continuous growth requires the generation of energy in the form of carbohydrates in the leaves upon photosynthesis and uptake of nutrients and water through root hairs. Root hair outgrowth depends on the overall condition of the plant and its energy level must be high enough to maintain root growth. TARGET OF RAPAMYCIN (TOR)-mediated signaling cascades serve as a hub to evaluate which resources are needed to respond to external stimuli and which are available to maintain proper plant adaptation. Root hair growth further requires appropriate distribution of the phytohormone auxin, which primes root hair cell fate and triggers root hair elongation. Auxin is transported in an active, directed manner by a plasma membrane located carrier. The auxin efflux carrier PIN-FORMED 2 is necessary to transport auxin to root hair cells, followed by subcellular rearrangements involved in root hair outgrowth. This review presents an overview of events upstream and downstream of PIN2 action, which are involved in root hair growth control.

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