scholarly journals WUSCHEL-related homeobox family genes in rice control lateral root primordium size

2022 ◽  
Vol 119 (1) ◽  
pp. e2101846119
Author(s):  
Tsubasa Kawai ◽  
Kyosuke Shibata ◽  
Ryosuke Akahoshi ◽  
Shunsaku Nishiuchi ◽  
Hirokazu Takahashi ◽  
...  
Keyword(s):  
Root System ◽  
Crop Production ◽  
Molecular Mechanisms ◽  
Lateral Roots ◽  
Root Tip ◽  
Early Developmental Stage ◽  
Dependent Manner ◽  
Mobility Shift ◽  
Causative Gene ◽  
Variable Environments

The development of a plastic root system is essential for stable crop production under variable environments. Rice plants have two types of lateral roots (LRs): S-type (short and thin) and L-type (long, thick, and capable of further branching). LR types are determined at the primordium stage, with a larger primordium size in L-types than S-types. Despite the importance of LR types for rice adaptability to variable water conditions, molecular mechanisms underlying the primordium size control of LRs are unknown. Here, we show that two WUSCHEL-related homeobox (WOX) genes have opposing roles in controlling LR primordium (LRP) size in rice. Root tip excision on seminal roots induced L-type LR formation with wider primordia formed from an early developmental stage. QHB/OsWOX5 was isolated as a causative gene of a mutant that is defective in S-type LR formation but produces more L-type LRs than wild-type (WT) plants following root tip excision. A transcriptome analysis revealed that OsWOX10 is highly up-regulated in L-type LRPs. OsWOX10 overexpression in LRPs increased the LR diameter in an expression-dependent manner. Conversely, the mutation in OsWOX10 decreased the L-type LR diameter under mild drought conditions. The qhb mutants had higher OsWOX10 expression than WT after root tip excision. A yeast one-hybrid assay revealed that the transcriptional repressive activity of QHB was lost in qhb mutants. An electrophoresis mobility shift assay revealed that OsWOX10 is a potential target of QHB. These data suggest that QHB represses LR diameter increase, repressing OsWOX10. Our findings could help improve root system plasticity under variable environments.

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 Modelling time variations of root diameter and elongation rate as related to assimilate supply and demand

2020 ◽  
Vol 71 (12) ◽  
pp. 3524-3534
Author(s):  
Loïc Pagès ◽  
Marie Bernert ◽  
Guillaume Pagès
Keyword(s):  
Root System ◽  
Root Elongation ◽  
Lateral Roots ◽  
Supply And Demand ◽  
Root System Architecture ◽  
Elongation Rate ◽  
Growth Patterns ◽  
Root Tip ◽  
Generic Model ◽  
Maximal Diameter

Abstract In a given root system, individual roots usually exhibit a rather homogeneous tip structure although highly different diameters and growth patterns, and this diversity is of prime importance in the definition of the whole root system architecture and foraging characteristics. In order to represent and predict this diversity, we built a simple and generic model at root tip level combining structural and functional knowledge on root elongation. The tip diameter, reflecting meristem size, is used as a driving variable of elongation. It varies, in response to the fluctuations of photo-assimilate availability, between two limits (minimal and maximal diameter). The elongation rate is assumed to be dependent on the transient value of the diameter. Elongation stops when the tip reaches the minimal diameter. The model could satisfactorily reproduce patterns of root elongation and tip diameter changes observed in various species at different scales. Although continuous, the model could generate divergent root classes as classically observed within populations of lateral roots. This model should help interpret the large plasticity of root elongation patterns which can be obtained in response to different combinations of endogenous and exogenous factors. The parameters could be used in phenotyping the root system.

scholarly journals Roles of Reactive Oxygen Species and Mitochondria in Seed Germination

2021 ◽  
Vol 12 ◽  
Author(s):  
Muhammad Awais Farooq ◽  
Xiaomeng Zhang ◽  
Muhammad Mubashar Zafar ◽  
Wei Ma ◽  
Jianjun Zhao
Keyword(s):  
Reactive Oxygen Species ◽  
Heat Shock ◽  
Seed Germination ◽  
Seed Dormancy ◽  
Energy Demand ◽  
Crop Production ◽  
Molecular Mechanisms ◽  
Reactive Oxygen ◽  
Dependent Manner ◽  
Oxygen Species

Seed germination is crucial for the life cycle of plants and maximum crop production. This critical developmental step is regulated by diverse endogenous [hormones, reactive oxygen species (ROS)] and exogenous (light, temperature) factors. Reactive oxygen species promote the release of seed dormancy by biomolecules oxidation, testa weakening and endosperm decay. Reactive oxygen species modulate metabolic and hormone signaling pathways that induce and maintain seed dormancy and germination. Endosperm provides nutrients and senses environmental signals to regulate the growth of the embryo by secreting timely signals. The growing energy demand of the developing embryo and endosperm is fulfilled by functional mitochondria. Mitochondrial matrix-localized heat shock protein GhHSP24.7 controls seed germination in a temperature-dependent manner. In this review, we summarize comprehensive view of biochemical and molecular mechanisms, which coordinately control seed germination. We also discuss that the accurate and optimized coordination of ROS, mitochondria, heat shock proteins is required to permit testa rupture and subsequent germination.

Development of white spruce (Picea glauca) seedling roots

1985 ◽  
Vol 63 (3) ◽  
pp. 456-462 ◽  
Author(s):  
Anne M. Johnson-Flanagan ◽  
John N. Owens
Keyword(s):  
Root System ◽  
Picea Glauca ◽  
Lateral Roots ◽  
Root Apex ◽  
White Spruce ◽  
Growth Cycle ◽  
Root Tip ◽  
System A ◽  
Seedling Roots ◽  
Specific Phase

The root system of container-grown white spruce seedlings (Picea glauca (Moench) Voss) consists of a taproot and many lateral roots. The lateral roots can be divided into three classes on the basis of external morphology. Although growth cycles of individual roots are independent, there are overall trends of growth in the root system. A preponderance of one morphological root class is usually associated with a specific phase of the growth cycle. Apical organization in absorbing and elongating roots is similar. When elongation ceases, roots become brown as a result of two separate processes, suberization of the endodermis and metacutization of a discrete layer enveloping the root apex. Zonation in the apex is reduced in brown roots. Renewed growth is marked by swelling of the brown root apex followed by the emergence of a white root tip.

scholarly journals Control of root system architecture by phytohormones and environmental signals in rice

2020 ◽  
Vol 67 (1-2) ◽  
pp. 98-109
Author(s):  
Chen Lin ◽  
Margret Sauter
Keyword(s):  
Root System ◽  
System Architecture ◽  
Crop Production ◽  
Molecular Mechanisms ◽  
Extreme Environments ◽  
Root System Architecture ◽  
Environmental Signals ◽  
Production Water ◽  
Environmental Extremes ◽  
Crown Roots

Drought and flooding are environmental extremes and major threats to crop production. Water uptake is achieved by plant roots which have to explore new soil spaces to alleviate water deficit during drought or to cope with water excess during flooding. Adaptation of the root system architecture helps plants cope with such extreme conditions and is crucial for plant health and survival. While for dicot plants the well studied model plant Arabidopsis thaliana has provided insight into the genetic and molecular regulation of the root system, less information is available for monocot species, which include the agronomically important cereal crops. Rice (Oryza sativa L.) is a semi-aquatic monocot plant that develops strong tolerance to flooding. Flooding tolerance of rice is closely linked to its adaptive root system. The functional root system of rice is mainly composed of crown roots and is shifted to nodal adventitious roots during flooding which allows rice to maintain oxygen supply to the roots and to survive longer periods of partial submergence as compared with other crops. Likewise, a number of drought-tolerance traits of rice are the result of an altered root system architecture. Hence, the structure of the root system adapts to, both, flooding and drought. Understanding the regulatory mechanisms that control root system adaptation to extreme environments is a key task for scientists to accelerate the breeding efforts for stress-tolerant crops. This review summarizes recently identified genes and molecular mechanisms that regulate root system architecture in rice in response to drought and flooding.

5-Aminolaevulinate synthase gene promoter contains two cAMP-response element (CRE)-like sites that confer positive and negative responsiveness to CRE-binding protein (CREB)

2001 ◽  
Vol 353 (2) ◽  
pp. 307-316 ◽  
Author(s):  
Luciana E. GIONO ◽  
Cecilia L. VARONE ◽  
Eduardo T. CÁNEPA
Keyword(s):  
Gene Expression ◽  
Promoter Activity ◽  
Molecular Mechanisms ◽  
Binding Protein ◽  
Phosphorylation Site ◽  
Gene Promoter ◽  
Site Directed Mutagenesis ◽  
Dependent Manner ◽  
Mobility Shift ◽  
Putative Transcription Factor

The first and rate-controlling step of the haem biosynthetic pathway in mammals and fungi is catalysed by the mitochondrial-matrix enzyme 5-aminolaevulinate synthase (ALAS). The purpose of this work was to explore the molecular mechanisms involved in the cAMP regulation of rat housekeeping ALAS gene expression. Thus we have examined the ALAS promoter for putative transcription-factor-binding sites that may regulate transcription in a cAMP-dependent protein kinase (PKA)-induced context. Applying both transient transfection assays with a chloramphenicol acetyltransferase reporter gene driven by progressive ALAS promoter deletions in HepG2, and electrophoresis mobility-shift assays we have identified two putative cAMP-response elements (CREs) at positions -38 and -142. Functional analysis showed that both CRE-like sites were necessary for complete PKA induction, but only one for basal expression. Co-transfection with a CRE-binding protein (CREB) expression vector increased PKA-mediated induction of ALAS promoter transcriptional activity. However, in the absence of co-transfected PKA, CREB worked as a specific repressor for ALAS promoter activity. A CREB mutant deficient in a PKA phosphorylation site was unable to induce expression of the ALAS gene but could inhibit non-stimulated promoter activity. Furthermore, a DNA-binding mutant of CREB did not interfere with ALAS promoter basal activity. Site-directed-mutagenesis studies showed that only the nearest element to the transcription start site was able to inhibit the activity of the promoter. Therefore, we conclude that CREB, through its binding to CRE-like sites, mediates the effect of cAMP on ALAS gene expression. Moreover, we propose that CREB could also act as a repressor of ALAS transcription, but is able to reverse its role after PKA activation. Dephosphorylated CREB would interfere in a spatial-disposition-dependent manner with the transcriptional machinery driving inhibition of gene expression.

scholarly journals Enhancing crop productivity by CRISPR-mediated genetic improvement of root architecture: a focus on phytohormones

2021 ◽  
Author(s):  
Nikola Kořínková ◽  
Irene Maria Fontana ◽  
Thu Nguyen ◽  
Pouneh Pouramini ◽  
Véronique Bergougnoux ◽  
...  
Keyword(s):  
Root System ◽  
System Architecture ◽  
Crop Production ◽  
Molecular Mechanisms ◽  
Daily Intake ◽  
Crop Productivity ◽  
Root System Architecture ◽  
Future Research ◽  
Limited Attention ◽  
Technical Advances

Food security is one of the main topics of today’s agriculture especially facing challenging environmental conditions. As most humankind has a daily intake of cereal grains, current breeding programs focus on these crop plants. Within the breeders’ toolbox, customised endonucleases became included after this universal application had been demonstrated. Due to technological restrictions, the main focus was on aboveground plant organs, while the essential belowground has been given only limited attention. In the present review, we summarise the knowledge on the root system architecture in cereals, the importance of phytohormones in this physiological process, and the molecular mechanisms involved. The review summarises how the use of the CRISPR methodology can improve the root system architecture to enhance crop production genetically. Finally, future research directions involving all this knowledge and technical advances are suggested.

scholarly journals Assessment of a 18F-Phenylboronic Acid Radiotracer for Imaging Boron in Maize

2020 ◽  
Vol 21 (3) ◽  
pp. 976 ◽  
Author(s):  
Alexandra B. Housh ◽  
Michaela S. Matthes ◽  
Amber Gerheart ◽  
Stacy L. Wilder ◽  
Kun-Eek Kil ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Lateral Roots ◽  
Phenylboronic Acid ◽  
Primary Root ◽  
Tissue Level ◽  
Root Tip ◽  
Dependent Manner ◽  
Micronutrient Deficiencies ◽  
Maize Roots ◽  
Dose Dependent

Boron (B) is an essential plant micronutrient. Deficiencies of B have drastic consequences on plant development leading to crop yield losses and reductions in root and shoot growth. Understanding the molecular and cellular consequences of B deficiency is challenging, partly because of the limited availability of B imaging techniques. In this report we demonstrate the efficacy of using 4-fluorophenylboronic acid (FPBA) as a B imaging agent, which is a derivative of the B deficiency mimic phenylboronic acid (PBA). We show that radioactively labelled [18F]FPBA (t½=110 m) accumulates at the root tip, the root elongation zone and at lateral root initiation sites in maize roots, and also translocates to the shoot where it accumulates along the leaf edges. Treatment of maize seedlings using FPBA and PBA causes a shortened primary root phenotype with absence of lateral roots in a dose-dependent manner. The primary root defects can be partially rescued by the addition of boric acid indicating that PBA can be used to induce B deficiency in maize and that radioactively labelled FPBA can be used to image sites of B demand on a tissue level.

scholarly journals Therapeutic Effects and Molecular Mechanisms of Ginkgo Biloba Extract on Liver Fibrosis in Rats

2006 ◽  
Vol 34 (01) ◽  
pp. 99-114 ◽  
Author(s):  
Shi-Quan Liu ◽  
Jie-Ping Yu ◽  
Hong-Lei Chen ◽  
He-Sheng Luo ◽  
Shi-Ming Chen ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Liver Fibrosis ◽  
Ginkgo Biloba ◽  
Molecular Mechanisms ◽  
Transforming Growth Factor ◽  
Stellate Cell ◽  
Ginkgo Biloba Extract ◽  
Therapeutic Effects ◽  
Dependent Manner ◽  
Mobility Shift

Oxidative stress can be implicated as a cause of liver fibrosis. In this sense, Ginkgo Biloba Extract (EGB), an antioxidant, may be beneficial in restraining liver fibrosis. The aim of this study was to evaluate the effects of EGB on experimental liver fibrosis. Rat liver fibrosis was induced by intraperitoneal injection of carbon tetrachloride ( CCl 4) twice a week for 8 weeks. Three groups of rats received EGB (0.25, 0.5 and 1.0 g/kg, respectively) by stomach everyday. CCl 4 administration induced liver fibrosis, which was inhibited by EGB in a dose-dependent manner. The histopathologic score of fibrosis, liver function and the levels of plasma hyaluronic acid (HA) and laminin (LN) were significantly improved in rats treated with CCl 4 + EGB , compared with those treated with CCl 4 only ( p < 0.01 or p < 0.05). The activities of superoxide dismutase (SOD) and glutathione pero xidase (GSH-Px) were notably elevated, while malondialdehyde (MDA) content was significantly decreased in the rats treated with CCl 4 + EGB ( p < 0.01 or p < 0.05). Inhibition of hepatic stellate cell (HSC) activation and nuclear factor kappaBP65 (NF-κBP65) expression was demonstrated in the livers of EGB-treated rats. The activation of NF-κB was significantly suppressed in EGB-treated rats determined by electrophoretic mobility shift assay (EMSA). Furthermore, EGB reduced expressions of transforming growth factor-β1 (TGF-β1) and collagen I mRNA. In conclusion, EGB is able to ameliorate liver injury and prevent rats from CCl 4-induced liver fibrosis by suppressing oxidative stress. This process may be related to inhibiting the induction of NF-κB on HSC activation and the expression of TGF-β1.

The Anti-Atherogenic Properties of Sesamin are Mediated via Improved Macrophage Cholesterol Efflux Through PPARγ1-LXRα and MAPK Signaling

2014 ◽  
Vol 84 (1-2) ◽  
pp. 79-91 ◽  
Author(s):  
Amin F. Majdalawieh ◽  
Hyo-Sung Ro
Keyword(s):  
Cholesterol Efflux ◽  
Transcriptional Activity ◽  
Molecular Mechanisms ◽  
Foam Cell ◽  
Mapk Signaling ◽  
Luciferase Reporter ◽  
Foam Cell Formation ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Macrophage Cholesterol Efflux

Background: Foam cell formation resulting from disrupted macrophage cholesterol efflux, which is triggered by PPARγ1 and LXRα, is a hallmark of atherosclerosis. Sesamin and sesame oil exert anti-atherogenic effects in vivo. However, the exact molecular mechanisms underlying such effects are not fully understood. Aim: This study examines the potential effects of sesamin (0, 25, 50, 75, 100 μM) on PPARγ1 and LXRα expression and transcriptional activity as well as macrophage cholesterol efflux. Methods: PPARγ1 and LXRα expression and transcriptional activity are assessed by luciferase reporter assays. Macrophage cholesterol efflux is evaluated by ApoAI-specific cholesterol efflux assays. Results: The 50 μM, 75 μM, and 100 μM concentrations of sesamin up-regulated the expression of PPARγ1 (p< 0.001, p < 0.001, p < 0.001, respectively) and LXRα (p = 0.002, p < 0.001, p < 0.001, respectively) in a concentration-dependent manner. Moreover, 75 μM and 100 μM concentrations of sesamin led to 5.2-fold (p < 0.001) and 6.0-fold (p<0.001) increases in PPAR transcriptional activity and 3.9-fold (p< 0.001) and 4.2-fold (p < 0.001) increases in LXR transcriptional activity, respectively, in a concentration- and time-dependent manner via MAPK signaling. Consistently, 50 μM, 75 μM, and 100 μM concentrations of sesamin improved macrophage cholesterol efflux by 2.7-fold (p < 0.001), 4.2-fold (p < 0.001), and 4.2-fold (p < 0.001), respectively, via MAPK signaling. Conclusion: Our findings shed light on the molecular mechanism(s) underlying sesamin’s anti-atherogenic effects, which seem to be due, at least in part, to its ability to up-regulate PPARγ1 and LXRα expression and transcriptional activity, improving macrophage cholesterol efflux. We anticipate that sesamin may be used as a therapeutic agent for treating atherosclerosis.

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