scholarly journals Antagonistic and auxin-dependent phosphoregulation of columella PIN proteins controls lateral root gravitropic setpoint angle in Arabidopsis

2019 ◽  
Author(s):  
Suruchi Roychoudhry ◽  
Katelyn Sageman-Furnas ◽  
Chris Wolverton ◽  
Heather L. Goodman ◽  
Peter Grones ◽  
...  
Keyword(s):  
Molecular Basis ◽  
Lateral Root ◽  
Auxin Transport ◽  
Lateral Roots ◽  
Gravity Vector ◽  
Independent Manner ◽  
Gravitropic Response ◽  
Auxin Distribution ◽  
Columella Cells ◽  
Molecular Framework

AbstractLateral roots of many species are maintained at non-vertical angles with respect to gravity. These gravitropic setpoint angles (GSAs) are intriguing because their maintenance requires that roots are able to effect gravitropic response both with and against the gravity vector. Here we have used the Arabidopsis lateral root in order to investigate the molecular basis of the maintenance of non-vertical GSAs. We show that gravitropism in the lateral root is angle-dependent and that both upward and downward graviresponse requires auxin transport and the generation of auxin asymmetries consistent with the Cholodny-Went model. We show that the symmetry in auxin distribution in lateral roots growing at GSA can be traced back to a net, balanced polarization of PIN3 and PIN7 auxin transporters in the columella cells. Further, upward and downward graviresponse in lateral roots correlates with corresponding changes in PIN3 and PIN7 polar localisation. Finally, we show that auxin, in addition to driving tropic growth in the lateral root, acts within the columella to regulate GSA via the PIN phosphatase subunit RCN1 in a PIN3-dependent and PIN7-independent manner. Together, these findings provide a molecular framework for understanding gravity-dependent nonvertical growth in Arabidopsis lateral roots.

Cadmium Inhibits Lateral Root Emergence in Rice by Disrupting OsPIN-Mediated Auxin Distribution and the Protective Effect of OsHMA3

2020 ◽  
Author(s):  
Han-Qing Wang ◽  
Wei Xuan ◽  
Xin-Yuan Huang ◽  
Chuanzao Mao ◽  
Fang-Jie Zhao
Keyword(s):  
Protective Effect ◽  
Lateral Root ◽  
Lateral Roots ◽  
Subsequent Development ◽  
Rice Cultivar ◽  
Inhibitory Effect ◽  
Auxin Distribution ◽  
Naphthylphthalamic Acid ◽  
Functional Alleles ◽  
Auxin Polar Transport

Abstract Cadmium (Cd) strongly inhibits root growth, especially the formation of lateral roots (LRs). The mechanism of Cd inhibition on LR formation in rice (Oryza sativa) remains unclear. In this study, we found that LR emergence in rice was inhibited significantly by 1 µM Cd and almost completely arrested by 5 µM Cd. Cd suppressed both the formation and subsequent development of the lateral root primordium (LRP). By using transgenic rice expressing the auxin response reporters DR5::GUS and DR5rev::VENUS, we found that Cd markedly reduced the auxin levels in the stele and LRP. Cd rapidly downregulated the expression of the auxin efflux transporter genes OsPIN1b, OsPIN1c and OsPIN9 in the stele and LRP. The emergence of LRs in a rice cultivar with a null allele of OsHMA3 (Heavy Metal ATPase 3) was more sensitive to Cd than cultivars with functional alleles. Overexpression of functional OsHMA3 in rice greatly alleviated the inhibitory effect of Cd, but the protective effect of OsHMA3 was abolished by the auxin polar transport inhibitor 1-N-naphthylphthalamic acid. The results suggest that Cd inhibits LR development in rice by disrupting OsPIN-mediated auxin distribution to LRP and OsHMA3 protects against Cd toxicity by sequestering Cd into the vacuoles.

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

1985 ◽  
Vol 63 (1) ◽  
pp. 21-24 ◽  
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.

scholarly journals The AtCRK5 Protein Kinase Is Required to Maintain the ROS NO Balance Affecting the PIN2-Mediated Root Gravitropic Response in Arabidopsis

2021 ◽  
Vol 22 (11) ◽  
pp. 5979
Author(s):  
Ágnes Cséplő ◽  
Laura Zsigmond ◽  
Norbert Andrási ◽  
Abu Imran Baba ◽  
Nitin M. Labhane ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Auxin Transport ◽  
Root Tip ◽  
Wild Type ◽  
Root Tips ◽  
H2o2 Treatment ◽  
Gravitropic Response ◽  
Auxin Distribution ◽  
Regulatory Loop ◽  
Oxidative Stress Inducer

The Arabidopsis AtCRK5 protein kinase is involved in the establishment of the proper auxin gradient in many developmental processes. Among others, the Atcrk5-1 mutant was reported to exhibit a delayed gravitropic response via compromised PIN2-mediated auxin transport at the root tip. Here, we report that this phenotype correlates with lower superoxide anion (O2•−) and hydrogen peroxide (H2O2) levels but a higher nitric oxide (NO) content in the mutant root tips in comparison to the wild type (AtCol-0). The oxidative stress inducer paraquat (PQ) triggering formation of O2•− (and consequently, H2O2) was able to rescue the gravitropic response of Atcrk5-1 roots. The direct application of H2O2 had the same effect. Under gravistimulation, correct auxin distribution was restored (at least partially) by PQ or H2O2 treatment in the mutant root tips. In agreement, the redistribution of the PIN2 auxin efflux carrier was similar in the gravistimulated PQ-treated mutant and untreated wild type roots. It was also found that PQ-treatment decreased the endogenous NO level at the root tip to normal levels. Furthermore, the mutant phenotype could be reverted by direct manipulation of the endogenous NO level using an NO scavenger (cPTIO). The potential involvement of AtCRK5 protein kinase in the control of auxin-ROS-NO-PIN2-auxin regulatory loop is discussed.

scholarly journals ABCB-mediated auxin transport in outer root tissues regulates lateral root spacing in Arabidopsis

2020 ◽  
Author(s):  
Jian Chen ◽  
Yangjie Hu ◽  
Pengchao Hao ◽  
Yuqin Zhang ◽  
Ohad Roth ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Gene Silencing ◽  
Lateral Root ◽  
Auxin Transport ◽  
Root Meristem ◽  
Lateral Roots ◽  
Root Branching ◽  
Export Activity ◽  
Root Tissues ◽  
Oscillation Zone

AbstractRoot branching is an important strategy to explore efficiently large volumes of soil. To economize this process, lateral roots (LR) are formed along the growing root at discrete positions that are instructed by oscillating auxin signals derived from the lateral root cap (LRC). This assumes that auxin moves from the LRC across multiple layers to accumulate in the pericycle. Here, we identified, using gene silencing and CRISPR based approaches, a group of five genetically linked, closely related ABCBs that control LR spacing by modulating the amplitude of the auxin oscillation. The transporters localize to the plasma membrane and reveal significant auxin export activity. These ABCBs are mainly expressed in the LRC and epidermis where they contribute to auxin transport towards the root oscillation zone. Our findings highlight the importance of auxin transport in the outer tissues of the root meristem to regulate LR spacing.

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.

scholarly journals Auxin-Induced SaARF4 Downregulates SaACO4 to Inhibit Lateral Root Formation in Sedum alfredii Hance

2021 ◽  
Vol 22 (3) ◽  
pp. 1297
Author(s):  
Dong Xu ◽  
Zhuchou Lu ◽  
Guirong Qiao ◽  
Wenmin Qiu ◽  
Longhua Wu ◽  
...  
Keyword(s):  
Lateral Root ◽  
Ethylene Biosynthesis ◽  
Luciferase Assay ◽  
Sedum Alfredii ◽  
Ethylene Synthesis ◽  
Root Tips ◽  
Sedum Alfredii Hance ◽  
Auxin Distribution ◽  
Distribution Mode ◽  
High Level

Lateral root (LR) formation promotes plant resistance, whereas high-level ethylene induced by abiotic stress will inhibit LR emergence. Considering that local auxin accumulation is a precondition for LR generation, auxin-induced genes inhibiting ethylene synthesis may thus be important for LR development. Here, we found that auxin response factor 4 (SaARF4) in Sedum alfredii Hance could be induced by auxin. The overexpression of SaARF4 decreased the LR number and reduced the vessel diameters. Meanwhile, the auxin distribution mode was altered in the root tips and PIN expression was also decreased in the overexpressed lines compared with the wild-type (WT) plants. The overexpression of SaARF4 could reduce ethylene synthesis, and thus, the repression of ethylene production decreased the LR number of WT and reduced PIN expression in the roots. Furthermore, the quantitative real-time PCR, chromatin immunoprecipitation sequencing, yeast one-hybrid, and dual-luciferase assay results showed that SaARF4 could bind the promoter of 1-aminocyclopropane-1-carboxylate oxidase 4 (SaACO4), associated with ethylene biosynthesis, and could downregulate its expression. Therefore, we concluded that SaARF4 induced by auxin can inhibit ethylene biosynthesis by repressing SaACO4 expression, and this process may affect auxin transport to delay LR development.

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 Control of auxin-regulated root development by the Arabidopsis thaliana SHY2/IAA3 gene

Development ◽  
1999 ◽  
Vol 126 (4) ◽  
pp. 711-721 ◽  
Author(s):  
Q. Tian ◽  
J.W. Reed
Keyword(s):  
Arabidopsis Thaliana ◽  
Lateral Root ◽  
Tissue Specificity ◽  
Plant Hormone ◽  
Root Formation ◽  
Auxin Transport ◽  
Feedback Regulation ◽  
Loss Of Function ◽  
Leaf Formation ◽  
Induced Genes

The plant hormone auxin controls many aspects of development and acts in part by inducing expression of various genes. Arabidopsis thaliana semidominant shy2 (short hypocotyl) mutations cause leaf formation in dark-grown plants, suggesting that SHY2 has an important role in regulating development. Here we show that the SHY2 gene encodes IAA3, a previously known member of the Aux/IAA family of auxin-induced genes. Dominant shy2 mutations cause amino acid changes in domain II, conserved among all members of this family. We isolated loss-of-function shy2 alleles including a putative null mutation. Gain-of-function and loss-of-function shy2 mutations affect auxin-dependent root growth, lateral root formation, and timing of gravitropism, indicating that SHY2/IAA3 regulates multiple auxin responses in roots. The phenotypes suggest that SHY2/IAA3 may activate some auxin responses and repress others. Models invoking tissue-specificity, feedback regulation, or control of auxin transport may explain these results.

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.

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