scholarly journals Flavonols modulate lateral root emergence by scavenging reactive oxygen species in Arabidopsis thaliana

2020 ◽  
pp. jbc.RA120.014543
Author(s):  
Jordan M. Chapman ◽  
Gloria K. Muday
Keyword(s):  
Arabidopsis Thaliana ◽  
Root Development ◽  
Lateral Root ◽  
Lateral Roots ◽  
Negative Regulator ◽  
Wild Type ◽  
Root Primordia ◽  
Lateral Root Primordia ◽  
Lateral Root Development ◽  
Genes Encoding

Flavonoids are a class of specialized metabolites with subclasses including flavonols and anthocyanins, which have unique properties as antioxidants. Flavonoids modulate plant development, but whether and how they impact lateral root development is unclear. We examined potential roles for flavonols in this process using Arabidopsis thaliana mutants with defects in genes encoding key enzymes in flavonoid biosynthesis. We observed the tt4 and fls1 mutants, which produce no flavonols, have increased lateral root emergence. The tt4 root phenotype was reversed by genetic and chemical complementation. To more specifically define the flavonoids involved, we tested an array of flavonoid biosynthetic mutants, eliminating roles for anthocyanins and the flavonols quercetin and isorhamnetin in modulating root development. Instead, two tt7 mutant alleles, with defects in a branchpoint enzyme blocking quercetin biosynthesis, formed reduced numbers of lateral roots, and tt7-2 had elevated levels of kaempferol. Using a flavonol-specific dye, we observed that in the tt7-2 mutant, kaempferol accumulated within lateral root primordia at higher levels than wild-type. These data are consistent with kaempferol, or downstream derivatives, acting as a negative regulator of lateral root emergence. We examined ROS accumulation using ROS-responsive probes and found reduced fluorescence of a superoxide-selective probe within the primordia of tt7-2 compared to wild type, but not in the tt4 mutant, consistent with opposite effects of these mutants on lateral root emergence. These results support a model in which increased level of kaempferol in the lateral root primordia of tt7-2 reduces superoxide concentration and ROS-stimulated lateral root emergence.

scholarly journals Flavonols modulate lateral root emergence by scavenging reactive oxygen species in Arabidopsis thaliana

2020 ◽  
Author(s):  
Jordan M. Chapman ◽  
Gloria K. Muday
Keyword(s):  
Arabidopsis Thaliana ◽  
Lateral Root ◽  
Lateral Roots ◽  
Negative Regulator ◽  
Antioxidant Compounds ◽  
Wild Type ◽  
Root Primordia ◽  
Lateral Root Primordia ◽  
Lateral Root Development ◽  
Genes Encoding

AbstractFlavonoids are plant-specific antioxidant compounds that modulate plant development, which include flavonols and anthocyanins subclasses. In Arabidopsis thaliana, mutants in genes encoding each step in the flavonoid biosynthetic pathway have been isolated. We used these mutants to examine the role of flavonols in initiation and emergence of lateral roots and asked whether this regulation occurs through scavenging ROS. The tt4 mutants have a defect in the first committed step of flavonoid biosynthesis and have increased lateral root emergence. This phenotype was reversed by both genetic and chemical complementation. Using these flavonoid biosynthetic mutants, we eliminated roles for anthocyanins and the flavonols, quercetin and isorhamnetin, in controlling lateral root development. The tt7-2 mutant has a defect in a branchpoint enzyme blocking quercetin biosynthesis that led to elevated levels of kaempferol and reduced lateral roots. Kaempferol accumulated within lateral root primordia and was significantly increased in tt7-2. Thee data are consistent with kaempferol acting as a negative regulator of lateral root emergence. We examined ROS accumulation above and within the primordia using a general ROS sensor and identified increased signal above the primordia of the tt4 and tt7-2 mutants compared to wild type. Using a superoxide specific sensor, we detected a decrease in signal within the primordia of tt7-2, but not the tt4 mutant, compared to wild type. Together, these results support a model in which increased level of kaempferol in tt7-2 leads to a reduction in superoxide concentration in the lateral root primordia thereby reducing ROS-stimulated lateral root emergence.

Organization and cell differentiation in lateral roots of Arabidopsis thaliana

Development ◽  
1997 ◽  
Vol 124 (1) ◽  
pp. 33-44 ◽  
Author(s):  
J.E. Malamy ◽  
P.N. Benfey
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Differentiation ◽  
Lateral Root ◽  
Lateral Roots ◽  
Cell Types ◽  
Cell Type ◽  
Root Primordia ◽  
Lateral Root Primordia ◽  
Lateral Root Development ◽  
Cell Type Specific

Lateral root formation in plants involves the stimulation of mature pericycle cells to proliferate and redifferentiate to create a new organ. The simple organization of the root of Arabidopsis thaliana allows the development of lateral root primordia to be characterized histologically. We have divided the process of lateral root development into 8 stages defined by specific anatomical characteristics and cell divisions. To identify the cell types in the developing primordium we have generated a collection of marker lines that express beta-glucuronidase in a tissue- or cell type-specific manner in the root. Using these tools we have constructed a model describing the lineage of each cell type in the lateral root. These studies show that organization and cell differentiation in the lateral root primordia precede the appearance of a lateral root meristem, with differential gene expression apparent after the first set of divisions of the pericycle.

scholarly journals A single cell view of the transcriptome during lateral root initiation in Arabidopsis thaliana

2020 ◽  
Author(s):  
Hardik P. Gala ◽  
Amy Lanctot ◽  
Ken Jean-Baptiste ◽  
Sarah Guiziou ◽  
Jonah C. Chu ◽  
...  
Keyword(s):  
Single Cell ◽  
Root Development ◽  
Lateral Root ◽  
Lateral Roots ◽  
Primary Root ◽  
Root Initiation ◽  
Lateral Root Primordia ◽  
Lateral Root Development ◽  
Lateral Root Initiation ◽  
Molecular Events

AbstractRoot architecture is a major determinant of fitness, and is under constant modification in response to favorable and unfavorable environmental stimuli. Beyond impacts on the primary root, the environment can alter the position, spacing, density and length of secondary or lateral roots. Lateral root development is among the best-studied examples of plant organogenesis, yet there are still many unanswered questions about its earliest steps. Among the challenges faced in capturing these first molecular events is the fact that this process occurs in a small number of cells with unpredictable timing. Single-cell sequencing methods afford the opportunity to isolate the specific transcriptional changes occurring in cells undergoing this fate transition. Using this approach, we successfully captured the transcriptomes of initiating lateral root primordia, and discovered many previously unreported upregulated genes associated with this process. We developed a method to selectively repress target gene transcription in the xylem pole pericycle cells where lateral roots originate, and demonstrated that expression of several of these targets was required for normal root development. We also discovered novel subpopulations of cells in the pericycle and endodermal cell files that respond to lateral root initiation, highlighting the coordination across cell files required for this fate transition.One sentence summarySingle cell RNA sequencing reveals new molecular details about lateral root initiation, including the transcriptional impacts of the primordia on bordering cells.

Analysis of lateral root growth in Arabidopsis in response to physiologically active auxin analogues

2010 ◽  
Vol 58 (1) ◽  
pp. 1-10 ◽  
Author(s):  
L. Novickienė ◽  
V. Gavelienė ◽  
L. Miliuvienė ◽  
D. Kazlauskienė ◽  
L. Pakalniškytė
Keyword(s):  
Lateral Root ◽  
Apical Meristem ◽  
Lateral Roots ◽  
Root System Architecture ◽  
Test Plant ◽  
Wild Type ◽  
Root Primordia ◽  
Lateral Root Primordia ◽  
Primary Roots ◽  
The Impact

The aim of this work was to investigate the formation and development of lateral roots in model trials on Arabidopsis thaliana L. Heynh wild type (Col-0), the alf4-1 mutant and its allele by applying the physiologically active auxin analogues IBA, IAA, TA-12 and TA-14.Differences were observed between the alf4-1 mutant and its allele phenotype in the formation of lateral roots. The application of auxin analogues was unable to restore the formation of lateral roots in the alf4-1 mutant. In some cases, under the impact of IBA (1 μM), a cluster of xylem cells was activated in the pericycle of the primary roots and lateral root primordia were formed. The auxin analogues induced the growth of primary roots in the alf4-1 allele and the formation and growth of lateral roots. The impact of IBA (1 μM), TA-12 (1 mM) and IAA (1 μM) was particularly evident. The intense formation of lateral roots under the impact of IBA and TA-12 could be related with the ability of these compounds to intensify mitotic activity in the apical meristem cells of the lateral roots. New data were obtained, showing that IBA and other physiologically active auxin analogues can modify the root system architecture of the test-plant Arabidopsis .

scholarly journals B1L regulates lateral root development by exocytic vesicular trafficking-mediated polar auxin transport

2021 ◽  
Author(s):  
Yang Gang ◽  
Chen Bi-xia ◽  
Chen Tao ◽  
Chen Jia-hui ◽  
Sun Rui ◽  
...  
Keyword(s):  
Root Development ◽  
Lateral Root ◽  
Auxin Transport ◽  
Polar Auxin Transport ◽  
Vesicular Trafficking ◽  
Root Initiation ◽  
Root Primordia ◽  
Lateral Root Primordia ◽  
Lateral Root Development ◽  
Lateral Root Initiation

Auxin and auxin-mediated signaling pathways involved in the regulation of lateral root development are well documented. Although exocytic vesicle trafficking plays an important role in PIN-auxin-efflux carrier recycling, and polar auxin transport during lateral root formation, however, the mechanistic details of these processes are not well understood. Here, we demonstrate an essential regulatory mechanism of B1L that interacts with the exocyst to regulate PIN-mediated polar auxin transport and lateral root initiation. B1L is highly expressed in Arabidopsis roots, and genetic and cellular analyses have revealed that B1L is mainly involved in lateral root primordia initiation. Furthermore, DR5::GUS expression analyses revealed that auxin levels were higher in lateral root primordia of the b1l mutant than in the wild-type. Exogenous auxin treatment confirmed that the lateral root phenotype correlated closely with auxin levels. Additionally, auxin transport-inhibitory treatment indicated that B1L regulates auxin efflux. Consistently, b1l mutants exhibited higher levels of auxin efflux carriers PIN1-GFP and PIN3-GFP in lateral root primordia. Moreover, B1L interacts with the exocyst and functions in recycling PIN2-GFP. Finally, the b1l-1/exo70b1-1 double-mutant exhibited a significant increase in the number of lateral roots compared to the wildtype, b1l-1, and exo70b1-1. Collectively, this study improves our understanding of the highly sophisticated processes involved in exocytic vesicular trafficking-mediated polar auxin transport and lateral root initiation in plants.

scholarly journals Cryptic variation in RNA-directed DNA-methylation controls lateral root development when auxin signalling is perturbed

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Zaigham Shahzad ◽  
Ross Eaglesfield ◽  
Craig Carr ◽  
Anna Amtmann
Keyword(s):  
Dna Methylation ◽  
Root Development ◽  
Transcriptional Repression ◽  
Lateral Root ◽  
Developmental Plasticity ◽  
Plant Root ◽  
Negative Regulator ◽  
Lateral Root Primordia ◽  
Lateral Root Development ◽  
Cryptic Variation

AbstractMaintaining the right balance between plasticity and robustness in biological systems is important to allow adaptation while maintaining essential functions. Developmental plasticity of plant root systems has been the subject of intensive research, but the mechanisms underpinning robustness remain unclear. Here, we show that potassium deficiency inhibits lateral root organogenesis by delaying early stages in the formation of lateral root primordia. However, the severity of the symptoms arising from this perturbation varies within a natural population of Arabidopsis and is associated with the genetic variation in CLSY1, a key component of the RNA-directed DNA-methylation machinery. Mechanistically, CLSY1 mediates the transcriptional repression of a negative regulator of root branching, IAA27, and promotes lateral root development when the auxin-dependent proteolysis pathway fails. Our study identifies DNA-methylation-mediated transcriptional repression as a backup system for post-translational protein degradation which ensures robust development and performance of plants in a challenging environment.

scholarly journals The Arabidopsis TTL3 protein interconnects brassinosteroid signalling and cytoskeleton during lateral root development

2020 ◽  
Author(s):  
Pengfei Xin ◽  
Jakub Schier ◽  
Ivan Kulich ◽  
Joseph G. Dubrovsky ◽  
Vielle-Calzada Jean-Philippe ◽  
...  
Keyword(s):  
Lateral Root ◽  
Lateral Roots ◽  
Subsequent Development ◽  
Loss Of Function ◽  
Root Primordia ◽  
Lateral Root Primordia ◽  
Lateral Root Development ◽  
Treatment Timing ◽  
Essential Components ◽  
Abiotic Interactions

AbstractLateral roots are essential components of the plant edaphic interface, contributing to water and nutrient uptake, biotic and abiotic interactions, stress survival, and plant anchorage. We have identified the TETRATRICOPEPTIDE-REPEAT THIOREDOXIN-LIKE 3 (TTL3) being related to lateral root emergence and later development. TTL3 interacts with microtubules and potentially interconnects cytoskeletal function with the brassinosteroid signalling pathway. Loss of function of TTL3 leads to a reduced number of emerged lateral roots due to delayed development of lateral root primordia. Lateral root growth of the ttl3 mutant is less sensitive to BR treatment. Timing and spatial distribution of TTL3 expression is consistent with its role in development of lateral root primordia before their emergence and subsequent development into lateral roots. TTL3 is a novel component of the root system morphogenesis regulatory network.

scholarly journals PRH1 mediates ARF7-LBD dependent auxin signaling to regulate lateral root development in Arabidopsis thaliana

2019 ◽  
Author(s):  
Feng Zhang ◽  
Wenqing Tao ◽  
Ruiqi Sun ◽  
Junxia Wang ◽  
Cuiling Li ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Transcription Factors ◽  
Root Development ◽  
Lateral Root ◽  
Lateral Roots ◽  
Auxin Signaling ◽  
Auxin Response ◽  
Cell Identity ◽  
Lateral Root Development ◽  
Lateral Organ

AbstractThe development of lateral roots in Arabidopsis thaliana is strongly dependent on signaling directed by the AUXIN RESPONSE FACTOR7 (ARF7), which in turn activates LATERAL ORGAN BOUNDARIES DOMAIN (LBD) transcription factors (LBD16, 18, 29 and 33). Here, the product of PRH1, a PR-1 homolog annotated previously as encoding a pathogen-responsive protein, was identified as a target of ARF7-mediated auxin signaling and also as participating in the development of lateral roots. PRH1 was shown to be strongly induced by auxin treatment, and plants lacking a functional copy of PRH1 formed fewer lateral roots. The transcription of PRH1 was controlled by the binding of both ARF7 and LBDs to its promoter region. An interaction was detected between PRH1 and GATA23, a protein which regulates cell identity in lateral root founder cells.Author SummaryIn Arabidopsis thaliana AUXIN RESPONSE FACTOR7 (ARF7)-mediated auxin signaling plays a key role in lateral roots (LRs) development. The LATERAL ORGAN BOUNDARIES DOMAIN (LBD) transcription factors (LBD16, 18, 29 and 33) act downstream of ARF7-mediated auxin signaling to control LRs formation. Here, the PR-1 homolog PRH1 was identified as a novel target of both ARF7 and LBDs (especially the LBD29) during auxin induced LRs formation, as both ARF7 and LBDs were able to bind to the PRH1 promoter. More interestingly, PRH1 has a physical interaction with GATA23, which has been also reported to be up-regulated by auxin and influences LR formation through its regulation of LR founder cell identity. Whether the interaction between GATA23 and PRH1 affects the stability and/or the activity of either (or both) of these proteins remains an issue to be explored. This study provides improves new insights about how auxin regulates lateral root development.

scholarly journals Arabidopsis AZG2, an auxin induced putative cytokinin transporter, regulates lateral root emergence

2020 ◽  
Author(s):  
Tomás M. Tessi ◽  
Sabine Brumm ◽  
Eva Winklbauer ◽  
Benjamin Schumacher ◽  
Carlos I. Lescano ◽  
...  
Keyword(s):  
Lateral Root ◽  
Lateral Roots ◽  
Root System Architecture ◽  
Fluorescence Signal ◽  
Loss Of Function ◽  
Wild Type ◽  
Root Primordia ◽  
Long Distance ◽  
Lateral Root Primordia ◽  
Transporter Family

ABSTRACTThe phytohormones cytokinin (CK) and auxin are key regulators of plant growth and development. During the last decade specialised transport mechanisms turned out to be the key for the control of local and long distance hormone distributions. In contrast to auxin, CK transport is poorly understood. Here we show that Arabidopsis thaliana AZG2, a member of the AZG purine transporter family, acts as CK transporter involved in the determination of the root system architecture. The expression of AtAZG2 is primarily auxin dependent and restricted to a small group of cells surrounding the lateral root primordia. Compared to wild type, mutants carrying loss-of-function alleles of Atazg2 have higher density of lateral roots, suggesting AZG2 as being part of a regulatory pathway in lateral root emergence. Moreover, azg2 mutants are partially insensitive to exogenously applied CK, which is consistent with the observation that the CK reporter gene TCSnpro:GFP showed lower fluorescence signal in the roots of azg2 mutants compared to those of wild type. These results indicate a defective CK signalling pathway in the region of lateral root primordia. By the integration of AtAZG2 subcellular localization and CK transport capacity data, our results allowed us to propose a local Auxin/CK signalling model for the regulation of lateral root emergence.

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