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 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.

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.

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 Shoot-derived miR2111 controls legume root and nodule development

2020 ◽  
Author(s):  
Mengbai Zhang ◽  
Huanan Su ◽  
Peter M. Gresshoff ◽  
Brett J. Ferguson
Keyword(s):  
Lateral Root ◽  
Lateral Roots ◽  
Ectopic Expression ◽  
Root System Architecture ◽  
Negative Regulator ◽  
Nodule Development ◽  
Wild Type ◽  
Root Branching ◽  
Autoregulation Of Nodulation ◽  
Cle Peptide

AbstractLegumes control their nodule numbers through the Autoregulation Of Nodulation (AON). Rhizobia infection stimulates the production of root-derived CLE peptide hormones that are translocated to the shoot where they regulate a new signal. We used soybean to demonstrate that this shoot-derived signal is miR2111, which is transported via phloem to the root where it targets transcripts of Too Much Love (TML), a negative regulator of nodulation. Shoot perception of rhizobia-induced CLE peptides suppresses miR2111 expression, resulting in TML accumulation in roots and subsequent inhibition of nodule organogenesis. Feeding synthetic mature miR2111 via the petiole increased nodule numbers per plant. Likewise, elevating miR2111 availability by over-expression promoted nodulation, while target mimicry of TML induced the opposite effect on nodule development in wild-type plants and alleviated the supernodulating and stunted root growth phenotypes of AON-defective mutants. Additionally, in non-nodulating wild-type plants, ectopic expression of miR2111 significantly enhanced lateral root emergence with a decrease in lateral root length and average root diameter. In contrast, hairy roots constitutively expressing the target mimic construct exhibited reduced lateral root density. Overall, these findings demonstrate that miR2111 is both the critical shoot-to-root factor that positively regulates root nodule development, and also acts to shape root system architecture via orchestrating the degree of root branching, as well as the length and thickness of lateral roots.

scholarly journals Carbohydrate-Binding Module of a Rice Endo-β-1,4-glycanase, OsCel9A , Expressed in Auxin-Induced Lateral Root Primordia, is Post-Translationally Truncated

2006 ◽  
Vol 47 (11) ◽  
pp. 1555-1571 ◽  
Author(s):  
Kouki Yoshida ◽  
Nobuyuki Imaizumi ◽  
Satoshi Kaneko ◽  
Yasushi Kawagoe ◽  
Akemi Tagiri ◽  
...  
Keyword(s):  
Lateral Root ◽  
Time Course ◽  
Oryza Sativa L ◽  
Lateral Roots ◽  
Organ Specificity ◽  
Glycoside Hydrolase Family ◽  
Carbohydrate Binding ◽  
Carbohydrate Binding Module ◽  
Root Primordia ◽  
Lateral Root Primordia

Abstract We report the cloning of a glycoside hydrolase family (GHF) 9 gene of rice ( Oryza sativa L. cv. Sasanishiki), OsCel9A , corresponding to the auxin-induced 51 kDa endo-1,4-β-glucanase (EGase). This enzyme reveals a broad substrate specificity with respect to sugar backbones (glucose and xylose) in β-1,4-glycans of type II cell wall. OsCel9A encodes a 640 amino acid polypeptide and is an ortholog of TomCel8 , a tomato EGase containing a carbohydrate-binding module (CBM) 2 sequence at its C-terminus. The expression of four rice EGase genes including OsCel9A showed different patterns of organ specificity and responses to auxin. OsCel9A was preferentially expressed during the initiation of lateral roots or subcultured root calli, but was hardly expressed during auxin-induced coleoptile elongation or in seed calli, in contrast to OsCel9D , a KORRIGAN ( KOR ) homolog. In situ localization of OsCel9A transcripts demonstrated that its expression was specifically up-regulated in lateral root primordia (LRP). Northern blotting analysis showed the presence of a single product of OsCel9A . In contrast, both mass spectrometric analyses of peptide fragments from purified 51 kDa EGase proteins and immunogel blot analysis of EGase proteins in root extracts using two antibodies against internal peptide sequences of OsCel9A revealed that the entire CBM2 region was post-translationally truncated from the 67 kDa nascent protein to generate 51 kDa EGase isoforms. Analyses of auxin concentration and time course dependence of accumulation of two EGase isoforms suggested that the translation and post-translational CBM2 truncation of the OsCel9A gene may participate in lateral root development.

scholarly journals Cell wall remodeling and vesicle trafficking mediate the root clock in Arabidopsis

2020 ◽  
Author(s):  
Guy Wachsman ◽  
Jingyuan Zhang ◽  
Miguel A. Moreno-Risueno ◽  
Charles T. Anderson ◽  
Philip N. Benfey
Keyword(s):  
Lateral Root ◽  
Structural Changes ◽  
Vesicle Trafficking ◽  
Lateral Roots ◽  
Primary Root ◽  
Root Primordia ◽  
Pavement Cell ◽  
Lateral Root Primordia ◽  
Periodic Gene ◽  
Significant Enrichment

AbstractIn Arabidopsis, lateral roots initiate along the primary root in a process preceded by periodic gene expression, a phenomenon known as the root clock. Many genes involved in lateral root initiation have been identified. However, very little is known about the structural changes underlying the initiation process nor about how root clock function is regulated. In genetic screens, we identified the vesicle trafficking regulators, GNOM and its suppressor, AGD3, as critical to root clock function. We show that GNOM is required for the proper distribution of pectin, a mediator of intercellular adhesion, and that pectin esterification state is essential for a functional root clock. We found that in sites of lateral root primordia emergence, both esterified and de-esterified pectin are differentially distributed. Using a reverse genetic approach, we identified significant enrichment of GO terms associated with pectin modifying enzymes in the oscillation zone were the root clock is established. In agreement with a recent study on the function of pectin in pavement cell morphogenesis, our results indicate that the balance between esterified and de-esterified pectin is essential for proper root clock function and the subsequent initiation of lateral root primordia.

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 Cell wall remodeling and vesicle trafficking mediate the root clock in Arabidopsis

Science ◽  
2020 ◽  
Vol 370 (6518) ◽  
pp. 819-823 ◽  
Author(s):  
Guy Wachsman ◽  
Jingyuan Zhang ◽  
Miguel A. Moreno-Risueno ◽  
Charles T. Anderson ◽  
Philip N. Benfey
Keyword(s):  
Lateral Root ◽  
Reverse Genetics ◽  
Vesicle Trafficking ◽  
Lateral Roots ◽  
Root Primordia ◽  
Lateral Root Primordia ◽  
Periodic Gene ◽  
Adenosine Phosphate ◽  
Gtpase Activation ◽  
Pectin Esterification

In Arabidopsis thaliana, lateral roots initiate in a process preceded by periodic gene expression known as the root clock. We identified the vesicle-trafficking regulator GNOM and its suppressor, ADENOSINE PHOSPHATE RIBOSYLATION FACTOR GTPase ACTIVATION PROTEIN DOMAIN3, as root clock regulators. GNOM is required for the proper distribution of pectin, a mediator of intercellular adhesion, whereas the pectin esterification state is essential for a functional root clock. In sites of lateral root primordia emergence, both esterified and de-esterified pectin variants are differentially distributed. Using a reverse-genetics approach, we show that genes controlling pectin esterification regulate the root clock and lateral root initiation. These results indicate that the balance between esterified and de-esterified pectin states is essential for proper root clock function and the subsequent initiation of lateral root primordia.

scholarly journals Same same, but different: growth responses of primary and lateral roots

2020 ◽  
Vol 71 (8) ◽  
pp. 2397-2411 ◽  
Author(s):  
Sascha Waidmann ◽  
Elizabeth Sarkel ◽  
Jürgen Kleine-Vehn
Keyword(s):  
Root System ◽  
Lateral Root ◽  
Growth Regulation ◽  
Lateral Roots ◽  
Primary Root ◽  
Spatial Arrangement ◽  
Root System Architecture ◽  
Growth Responses ◽  
Lateral Root Primordia ◽  
Organ Growth

Abstract The root system architecture describes the shape and spatial arrangement of roots within the soil. Its spatial distribution depends on growth and branching rates as well as directional organ growth. The embryonic primary root gives rise to lateral (secondary) roots, and the ratio of both root types changes over the life span of a plant. Most studies have focused on the growth of primary roots and the development of lateral root primordia. Comparably less is known about the growth regulation of secondary root organs. Here, we review similarities and differences between primary and lateral root organ growth, and emphasize particularly how external stimuli and internal signals differentially integrate root system growth.

Sign in / Sign up

Export Citation Format

Share Document