The Lotus japonicus AFB6 Gene Is Involved in the Auxin Dependent Root Developmental Program

Auxin is essential for root development, and its regulatory action is exerted at different steps from perception of the hormone up to transcriptional regulation of target genes. In legume plants there is an overlap between the developmental programs governing lateral root and N2-fixing nodule organogenesis, the latter induced as the result of the symbiotic interaction with rhizobia. Here we report the characterization of a member of the L. japonicus TIR1/AFB auxin receptor family, LjAFB6. A preferential expression of the LjAFB6 gene in the aerial portion of L. japonicus plants was observed. Significant regulation of the expression was not observed during the symbiotic interaction with Mesorhizobium loti and the nodule organogenesis process. In roots, the LjAFB6 expression was induced in response to nitrate supply and was mainly localized in the meristematic regions of both primary and lateral roots. The phenotypic analyses conducted on two independent null mutants indicated a specialized role in the control of primary and lateral root elongation processes in response to auxin, whereas no involvement in the nodulation process was found. We also report the involvement of LjAFB6 in the hypocotyl elongation process and in the control of the expression profile of an auxin-responsive gene.

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Natural variation identifies a Pxy gene controlling root vascular organization and formation of nodules and lateral roots in Lotus japonicus

10.1101/2020.04.08.031260 ◽

2020 ◽

Author(s):

Yasuyuki Kawaharada ◽

Niels Sandal ◽

Vikas Gupta ◽

Haojie Jin ◽

Maya Kawaharada ◽

...

Keyword(s):

Lateral Root ◽

Reverse Genetics ◽

De Novo ◽

Lateral Roots ◽

Lotus Japonicus ◽

Nodule Formation ◽

Mesorhizobium Loti ◽

Genetic Overlap ◽

Natural Variants ◽

Trait Locus

AbstractForward and reverse genetics using the model legumes Lotus japonicus and Medicago truncatula have been instrumental for identifying the essential genes governing legume-rhizobial symbiosis. However, little is known about the effects of intraspecific variation on symbiotic signaling. The Lotus accessions Gifu and MG20 show differentiated phenotypic responses to the Mesorhizobium loti exoU mutant that produces truncated exopolysaccharides. Using Quantitative Trait Locus sequencing (QTL-seq), we identify the Pxy gene as a component of this differential exoU response. Lotus Pxy encodes a leucine-rich-repeat kinase similar to Arabidopsis PXY, which regulates stem vascular development. We show that Lotus pxy insertion mutants display defects in root vascular organization, as well as lateral root and nodule formation. Our work links Pxy to de novo organogenesis in the root, highlights the genetic overlap between regulation of lateral root and nodule formation, and demonstrates that specific natural variants of Pxy differentially affect nodulation signaling.

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T-DNA Tagging of Nodulation- and Root-Related Genes in Lotus japonicus: Expression Patterns and Potential for Promoter Trapping and Insertional Mutagenesis

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.1999.12.4.275 ◽

1999 ◽

Vol 12 (4) ◽

pp. 275-284 ◽

Cited By ~ 42

Author(s):

Luca Martirani ◽

Jiri Stiller ◽

Rossana Mirabella ◽

Flora Alfano ◽

Alessandro Lamberti ◽

...

Keyword(s):

Lateral Root ◽

Insertional Mutagenesis ◽

High Efficiency ◽

Expression Patterns ◽

Lotus Japonicus ◽

Selection Strategy ◽

Nodule Formation ◽

Mesorhizobium Loti ◽

Root Organogenesis ◽

Gusa Gene

High-efficiency transformation of the autogamous diploid legume Lotus japonicus by means of Agrobacterium rhizogenes was used to develop plant lines expressing a promoter-less gusA gene in a nodulation- or lateral root-associated manner. The approach exploits the putatively preferential integration of T-DNA into actively transcribed regions, thereby providing an enrichment for gene tagging events associated with the quickly assayable activation of a gusA promoter-less construct. Taking advantage of this enrichment and selection strategy, a T-DNA tagging program was initiated and screening for β-glucuronidase (GUS) activity was performed on root clones isolated after transformation with a gusA-promoter-less binary vector. The aim of this approach is the identification of genes involved in nodule formation induced by Mesorhizobium loti, lateral root organogenesis, and the eventual isolation of corresponding mutants. A large collection (220) of GUS-positive transformants showing a variety of expression patterns in different regions of roots and nodules was obtained; a preliminary molecular characterization of these plants is presented.

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Geoperception in primary and lateral roots of Phaseolus vulgaris (Fabaceae). III. A model to explain the differential georesponsiveness of primary and lateral roots

Canadian Journal of Botany ◽

10.1139/b85-004 ◽

1985 ◽

Vol 63 (1) ◽

pp. 21-24 ◽

Cited By ~ 14

Author(s):

J. Steven Ransom ◽

Randy Moore

Keyword(s):

Phaseolus Vulgaris ◽

Concentration Gradient ◽

Lateral Root ◽

Lateral Roots ◽

Primary Root ◽

Growth Inhibitors ◽

Gravitropic Response ◽

Primary Roots ◽

Primary And Lateral Roots

Half-tipped primary and lateral roots of Phaseolus vulgaris bend toward the side of the root on which the intact half tip remains. Therefore, tips of lateral and primary roots produce growth effectors capable of inducing gravicurvature. The asymmetrical placement of a tip of a lateral root onto a detipped primary root results in the root bending toward the side of the root onto which the tip was placed. That is, the lesser graviresponsiveness of lateral roots as compared with primary roots is not due to the inability of their caps to produce growth inhibitors. The more pronounced graviresponsiveness of primary roots is positively correlated with the presence of columella tissues that are 3.8 times longer, 1.7 times wider, and 10.5 times more voluminous than the columellas of lateral roots. We propose that the lack of graviresponsiveness exhibited by lateral roots is due to the facts that they (i) produce smaller amounts of the inhibitor than primary (i.e., strongly graviresponsive) roots and (ii) are unable to redistribute the inhibitor so as to be able to create a concentration gradient sufficient to induce a pronounced gravitropic response.

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Secondary metabolite profiling of the model legume Lotus japonicus during its symbiotic interaction with Mesorhizobium loti

Symbiosis ◽

10.1007/s13199-010-0053-7 ◽

2010 ◽

Vol 50 (3) ◽

pp. 119-128 ◽

Cited By ~ 7

Author(s):

N. Rispail ◽

B. Hauck ◽

B. Bartholomew ◽

A. A. Watson ◽

R. J. Nash ◽

...

Keyword(s):

Secondary Metabolite ◽

Metabolite Profiling ◽

Lotus Japonicus ◽

Symbiotic Interaction ◽

Model Legume ◽

Mesorhizobium Loti

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Lateral root formation and nutrients: nitrogen in the spotlight

Plant Physiology ◽

10.1093/plphys/kiab145 ◽

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.

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Identification of Symbiotically Defective Mutants of Lotus japonicus Affected in Infection Thread Growth

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-19-1444 ◽

2006 ◽

Vol 19 (12) ◽

pp. 1444-1450 ◽

Cited By ~ 20

Author(s):

Fabien Lombardo ◽

Anne B. Heckmann ◽

Hiroki Miwa ◽

Jillian A. Perry ◽

Koji Yano ◽

...

Keyword(s):

Root Hair ◽

Plant Cell Wall ◽

Plant Root ◽

Lotus Japonicus ◽

Cortical Cell ◽

Host Cells ◽

Infection Thread ◽

Mycorrhizal Symbiosis ◽

Symbiotic Interaction ◽

Infection Threads

During the symbiotic interaction between legumes and rhizobia, the host cell plasma membrane and associated plant cell wall invaginate to form a tunnel-like infection thread, a structure in which bacteria divide to reach the plant root cortex. We isolated four Lotus japonicus mutants that make infection pockets in root hairs but form very few infection threads after inoculation with Mesorhizobium loti. The few infection threads that did initiate in the mutants usually did not progress further than the root hair cell. These infection-thread deficient (itd) mutants were unaffected for early symbiotic responses such as calcium spiking, root hair deformation, and curling, as well as for the induction of cortical cell division and the arbuscular mycorrhizal symbiosis. Complementation tests and genetic mapping indicate that itd2 is allelic to Ljsym7, whereas the itd1, itd3, and itd4 mutations identified novel loci. Bacterial release into host cells did occur occasionally in the itd1, itd2, and itd3 mutants suggesting that some infections may succeed after a long period and that infection of nodule cells could occur normally if the few abnormal infection threads that were formed reached the appropriate nodule cells.

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Formation of lateral root meristems is a two-stage process

Development ◽

10.1242/dev.121.10.3303 ◽

1995 ◽

Vol 121 (10) ◽

pp. 3303-3310 ◽

Cited By ~ 8

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.

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In vitro growth and indoleacetic acid production by Mesorhizobium loti SEMIA806 and SEMIA816 under the influence of copper ions

Microbiology Research ◽

10.4081/mr.2017.7302 ◽

2017 ◽

Vol 8 (2) ◽

Cited By ~ 2

Author(s):

Jéssica Dutra Vieira ◽

Paulo Roberto Diniz Da Silva ◽

Valdir Marcos Stefenon

Keyword(s):

Contaminated Soils ◽

Acid Production ◽

Indoleacetic Acid ◽

Copper Ions ◽

Control Culture ◽

Control Treatment ◽

Symbiotic Interaction ◽

Mesorhizobium Loti ◽

Significant Difference

The indoleacetic acid produced by symbiotic bacteria is an important phytohormone signaling microbe-plant interaction, being therefore essential for rhizoremediation. In this study, the effect of different concentrations of copper ions on the bacterial growth and indoleacetic acid production was investigated in two strains of Mesorhizobium loti in in vitro conditions, aiming to determine critical concentrations of this heavy metal for rhizoremediation of contaminated soils using this bacterium. The experiment consisted on a control culture without copper and three treatments supplemented with 10 mg.L-1, 20 mg.L-1 or 50 mg.L-1 of CuSO4. For both strains, the growth stopped after 48h and no significant difference was observed across treatments. The production of indoleacetic acid by the control treatment without copper was significantly higher in comparison to the copper- containing treatments. Mesorhizobium loti SEMIA806 and SEMIA816 are resistant to up to 50 mg.L-1 of CuSO4 in the culture medium, presenting effective growth. The synthesis of indoleacetic acid was strongly reduced but not excluded by ions copper in the medium. So, it is expected that environmental copper found in the soil up to the concentration of 50 mg.L-1 will not preclude the symbiotic interaction between M. loti and leguminous host plant in rhizoremediation enterprises.

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

10.20944/preprints202003.0046.v1 ◽

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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ALotus japonicusE3 ligase interacts with the Nod factor receptor 5 and positively regulates nodulation

10.1101/269506 ◽

2018 ◽

Author(s):

Daniela Tsikou ◽

Estrella E. Ramirez ◽

Ioanna S. Psarrakou ◽

Jaslyn E. Wong ◽

Dorthe B. Jensen ◽

...

Keyword(s):

Lotus Japonicus ◽

E3 Ligase ◽

Kinase Domain ◽

Plant Interactions ◽

Post Translational Modification ◽

Direct Role ◽

Nod Factor ◽

Mesorhizobium Loti ◽

Signaling Systems ◽

Nodulation Capacity

SUMMARYPost-translational modification of receptor proteins is involved in activation and de-activation of signaling systems in plants. Both ubiquitination and deubiquitination have been implicated in plant interactions with pathogens and symbionts. Here we presentLjPUB13, a PUB-ARMADILLO repeat E3 ligase that specifically ubiquitinates the kinase domain of the Nod Factor receptor NFR5 and has a direct role in nodule organogenesis events inLotus japonicus. Phenotypic analyses of three LORE1 retroelement insertion plant lines revealed thatpub13plants display delayed and reduced nodulation capacity and retarded growth.LjPUB13expression is spatially regulated during symbiosis withMesorhizobium loti, with increased levels in young developing nodules. Thus,LjPUB13 is an E3 ligase with a positive regulatory role during the initial stages of nodulation inL. japonicus.

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