Protein-protein interaction (PPI) network analysis reveals important hub proteins and sub-network modules for root development in rice (Oryza sativa)

BACKGROUND

The root system is vital to plant growth and survival. Therefore, genetic improvement of the root system is beneficial for developing stress-tolerant and improved plant varieties. This requires the identification of proteins that significantly contribute to root development. Analyzing protein-protein interaction (PPI) networks is vastly beneficial in studying developmental phenotypes, such as root development, because a phenotype is an outcome of several interacting proteins. PPI networks can be analyzed to identify modules and get a global understanding of important proteins governing the phenotypes. PPI network analysis for root development in rice has not been performed before and has the potential to yield new findings to improve stress tolerance.

RESULTS

Here, the network module for root development was extracted from the global Oryza sativa PPI network retrieved from the STRING database. Novel protein candidates were predicted, and hub proteins and sub-modules were identified from the extracted module. The validation of the predictions yielded 75 novel candidate proteins, 6 sub-modules, 20 intramodular hubs, and 2 intermodular hubs.

CONCLUSIONS

These results show how the PPI network module is organized for root development and can be used for future wet-lab studies for producing improved rice varieties.

Micro-computed tomography evaluation of the effects of orthodontic force on immature maxillary first molars and alveolar bone mineral density of Sprague-Dawley rats

Objective

To investigate changes in the immature teeth of Sprague-Dawley rats during orthodontic treatment and to explore the changes in the peri-radicular alveolar bone through micro-computed tomography (CT).

Methods

Twenty-five 26-day-old male Sprague-Dawley rats were included. The maxillary left first molar was moved mesially under a continuous force of 30 cN, and the right first molar served as the control. After orthodontic treatment for 7, 14, 21, 28, and 42 days, the root length, tooth volume, and alveolar bone mineral density (BMD) around the mesial root were measured through micro-CT.

Results

The immature teeth continued to elongate after application of orthodontic force. The root length on the force side was significantly smaller than that on the control side, whereas the differences in the volume change between both sides were not statistically significant. Alveolar bone in the coronal part of the compression and tension sides showed no difference in BMD between the experimental and control groups. The BMD of the experimental group decreased from day 14 to day 42 in the apical part of the compression side and increased from day 7 to day 42 in the apical part of the tension side. The BMD of the experimental group decreased in the root apex part on day 7.

Conclusions

The root length and volume of immature teeth showed continued development under orthodontic forces. Alveolar bone resorption was observed on the compression side, and bone formation was observed on the tension side.

RETINOBLASTOMA-RELATED interactions with key factors of the RNA-directed DNA methylation (RdDM) pathway and its influence on root development

MAIN CONCLUSION

Our study presents evidence for a novel mechanism for RBR function in transcriptional gene silencing by interacting with key players of the RdDM pathway in Arabidopsis and several plant clades. Transposable elements and other repetitive elements are silenced by the RNA-directed DNA methylation pathway (RdDM). In RdDM, POLIV-derived transcripts are converted into double-stranded RNA (dsRNA) by the activity of RDR2 and subsequently processed into 24 nucleotide short interfering RNAs (24-nt siRNAs) by DCL3. 24-nt siRNAs serve as guides to direct AGO4-siRNA complexes to chromatin-bound POLV-derived transcripts generated from the template/target DNA. The interaction between POLV, AGO4, DMS3, DRD1, RDM1 and DRM2 promotes DRM2-mediated de novo DNA methylation. The Arabidopsis Retinoblastoma protein homolog (RBR) is a master regulator of the cell cycle, stem cell maintenance, and development. We in silico predicted and explored experimentally the protein-protein interactions (PPIs) between RBR and members of the RdDM pathway. We found that the largest subunits of POLIV and POLV (NRPD1 and NRPE1), the shared second largest subunit of POLIV and POLV (NRPD/E2), RDR1, RDR2, DCL3, DRM2, and SUVR2 contain canonical and non-canonical RBR binding motifs and several of them are conserved since algae and bryophytes. We validated experimentally PPIs between Arabidopsis RBR and several of the RdDM pathway proteins. Moreover, seedlings from loss-of-function mutants in RdDM and RBR show similar phenotypes in the root apical meristem. We show that RdDM and SUVR2 targets are up-regulated in the 35S:AmiGO-RBR background.

Flavonols modulate plant development, signaling, and stress responses

Flavonols are plant-specialized metabolites with important functions in plant growth and development. Isolation and characterization of mutants with reduced flavonol levels, especially the transparent testa mutants in Arabidopsis thaliana, have contributed to our understanding of the flavonol biosynthetic pathway. These mutants have also uncovered the roles of flavonols in controlling development in above- and below-ground tissues, notably in the regulation of root architecture, guard cell signaling, and pollen development. In this review, we present recent progress made towards a mechanistic understanding of flavonol function in plant growth and development. Specifically, we highlight findings that flavonols act as reactive oxygen species (ROS) scavengers and inhibitors of auxin transport in diverse tissues and cell types to modulate plant growth and development and responses to abiotic stresses.

Effects of antibiotics stress on root development, seedling growth, antioxidant status and abscisic acid level in wheat (Triticum aestivum L.)

The veterinary antibiotics contamination in agroecosystems is a substantial problem globally. However, little is known about their toxicity to crops, especially in wheat. This study evaluated the phytotoxic effects of the two most representative antibiotics, namely oxytetracycline (OTC) and enrofloxacin (ENR), on seed germination, seedling growth, root elongation and antioxidant status in wheat, and investigated the response of abscisic acid (ABA) to antibiotic stress and its underlying mechanism. The results showed that OTC and ENR under the experimental concentrations (5, 10, 20, 40 and 80 mg·L^-1) had no influence on seed germination of wheat. The reduced root length, fresh weight and surface area were observed when the concentrations of OTC and ENR were higher than 10 mg·L^-1 and 5 mg·L^-1, respectively. High concentrations (＞40 mg·L^-1) of antibiotics dramatically decreased the root length, fresh weight, root numbers and surface area as well as the number of stele cells and stele area. The activity of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD), and malondialdehyde (MDA) content in shoots and roots were increased with the increasing OTC and ENR concentrations. High concentrations (＞40 mg·L^-1) of antibiotics improved ABA content and enhanced the transcription levels of genes related to ABA biosynthesis (TaNCED1 and TaNCED2) and metabolism (TaABA8'OH1-A and TaABA8'OH2-A) in shoots and roots of wheat seedlings. Wheat seedlings had relatively strong sensitivity to low concentration (5 mg·L^-1) of ENR. These results suggest that OTC and ENR modulate root development and seedling growth by regulating ABA level and antioxidant defense system in wheat.

An apple NITRATE REDUCTASE 2 gene positively regulates nitrogen utilization and abiotic stress tolerance in Arabidopsis and apple callus

Nitrogen (N) is an essential element that plays an important role in crop biomass accumulation and quality formation. Increased crop yield is relied on excessive application of fertilizers, which usually leads to environmental pollution and unsustainable development. Thus, identification and characterization of genes involved in promoting nitrogen use efficiency is of high priority in crop breeding. The activity of nitrate reductase (NR) plays a critical role in nitrogen metabolism. In model plant Arabidopsis, NITRATE REDUCTASE 2 (NIA2), one of the two NRs, is responsible for about 90% of the NR activity. In this study, MdNIA2 gene in apple (Malus domestica) genome was screened out and identified by using AtNIA2 as bait. Phylogenetic analysis revealed that MdNIA2 had the closest evolutionary relationship with MbNIA from Malus baccata. Ectopic expression of MdNIA2 in Arabidopsis elevated the nitrogen use efficiency and increased root hair elongation and formation, resulting in promoted plant growth. Furthermore, the overexpression of MdNIA2 improved salt and drought tolerance in transgenic Arabidopsis and improved the salt tolerance of transgenic apple callus, and MdNIA2-reagualted NO metabolism might contribute to the abiotic stress tolerance. Overall, our data indicate the critical role of MdNIA2 in regulating nitrogen utilization efficiency and abiotic stress responses.

Ubiquitin-Conjugating Enzyme OsUBC11 Affects the Development of Roots via Auxin Pathway

Rice has 48 ubiquitin-conjugating enzymes, and the functions of most of these enzymes have not been elucidated. In the present study, a T-DNA insertional mutant named R164, which exhibited a significant decrease in the length of primary and lateral roots, was used as the experimental material to explore the potential function of OsUBC11. Analysis using the SEFA-PCR method showed that the T-DNA insertion was present in the promoter region of OsUBC11 gene, which encodes ubiquitin-conjugating enzyme (E2), and activates its expression. Biochemical experiments showed that OsUBC11 is a lysine-48-linked ubiquitin chain-forming conjugase. OsUBC11 overexpression lines showed the same root phenotypes. These results demonstrated that OsUBC11 was involved in root development. Further analyses showed that the IAA content of R164 mutant and OE3 line were significantly lower compared with wild-type Zhonghua11. Application of exogenous NAA restored the length of lateral and primary roots in R164 and OsUBC11 overexpression lines. Expression of the auxin synthesis regulating gene OsYUCCA4/6/7/9, the auxin transport gene OsAUX1, auxin/indole-3-acetic acid (Aux/IAA) family gene OsIAA31, auxin response factor OsARF16 and root regulator key genes, including OsWOX11, OsCRL1, OsCRL5 was significantly down-regulated in OsUBC11 overexpressing plants. Collectively, these results indicate that OsUBC11 modulates auxin signaling, ultimately affecting root development at the rice seedling stage.

Root response and phosphorus uptake with enhancement in available phosphorus level in soil in the presence of water-soluble organic matter deriving from organic material

Understanding the available phosphorus (P) levels in the presence of water-soluble organic matter (WSOM) deriving from organic materials can be important for the improvement of the P use efficiency. This study aimed to: (i) determine which types of WSOM (deriving from the organic material) can suppress P immobilization, and (ii) understand whether plants can uptake P that the immobilization is suppressed by the presence of WSOM, as well as how the plant roots response depending on the available P levels. The P sorption test revealed that the presence of WSOM deriving from cattle manure compost (CM), sewage sludge compost (SSC), and hydrothermal decomposed liquid fertilizer (HDLF) can suppress the P sorption by 44, 44, and 24%, respectively, as compared to single P. In the incubation test, the percentage of the available P to that added as P fertilizer was found to be >21% higher in the presence of a CM- or a SSC-derived WSOM than those of single P, but the effect of the HDLF-derived WSOM was not. In the cultivation test, P uptake was found to be improved in the CM-, the SSC-, and the HDLF-deriving WSOM by 17, 13, and 11%, respectively, as compared to single P. Moreover, the root weight was found to decrease along with an increase in the amount of P uptaken by the plant. These findings provide the first experimental evidence that the presence of the WSOM deriving from CM, SSC, and HDLF simultaneously enhance the available P level in the soil and P uptake by the plant at the lab-scale test. In addition, the higher the available P levels in the presence of WSOM, the lower the root developments. The presence of WSOM, particularly of one of high maturity, can suppress the P sorption by 24-44%; as a result, >20% of the P added remains as the available P depending on the type of organic material used.

Photolysis of caged cytokinin in single cells of Arabidopsis thaliana

BACKGROUND

Cytokinins are a class of phytohormone that play a crucial role in the development of plants. They are involved in the regulation of nearly every aspect of plant growth, from germination to senescence. The role of cytokinins in many developmental programs is complex and varies both spatially and temporally. Current techniques used to investigate the functions of cytokinins in plant development lack this spatial and temporal resolution required to observe cell-type specific effects.

RESULTS

To this end, we present a method of activating a caged cytokinin in single cells. A caged benzyladenine was synthesized, along with caged adenine as a negative control. In vitro testing confirmed ultraviolet light-mediated uncaging, and subsequent root growth assays demonstrated that uncaging produced a cytokinin phenotype. This uncaging was confined to single cells using multiphoton confocal microscopy. Using an Arabidopsis thaliana cytokinin reporter line expressing TCSn::GFP, the resulting GFP expression was confined to the uncaging region, including in single cells. This study presents a novel cell-targeted method of cytokinin delivery, which has the potential to elucidate a broad range of processes in plant development.

CONCLUSIONS

We combined multiphoton confocal microscopy and a caged cytokinin treatment, allowing cell type-specific uncaging of a cytokinin in Arabidopsis roots.

Liriodendron chinense LcMAX1 regulates primary root growth and shoot branching in Arabidopsis thaliana

Strigolactones (SLs) play prominent roles in regulating shoot branching and root architecture in model plants. However, their roles in non-model (particularly woody) plants remain unclear. Liriodendron chinense is a timber tree species widely planted in southern China. The outturn percentage and wood quality of L. chinense are greatly affected by the branching characteristics of its shoot, and the rooting ability of the cuttings is key for its vegetative propagation. Here, we isolated and analyzed the function of the MORE AXILLARY GROWTH 1 (LcMAX1) gene, which is involved in L. chinense SL biosynthesis. RT-qPCR showed that LcMAX1 was highly expressed in the roots and axillary buds. LcMAX1 was located in the endoplasmic reticulum (ER) and nucleus. LcMAX1 ectopic expression promoted primary root growth, whereas there were no phenotypic differences in shoot branching between transgenic and wild-type (WT) A. thaliana plants. LcMAX1 overexpression in the max1 mutant restored them to the WT A. thaliana phenotypes. Additionally, AtPIN1, AtPIN2, and AtBRC1 expressions were significantly upregulated in transgenic A. thaliana and the max1 mutant. It was therefore speculated that LcMAX1 promotes primary root growth by regulating expression of auxin transport-related genes in A. thaliana, and LcMAX1 inhibits shoot branching by upregulating expression of AtBRC1 in the max1 mutant. Altogether, these results demonstrated that the root development and shoot branching functions of LcMAX1 were similar to those of AtMAX1. Our findings provide a foundation for obtaining further insights into root and branch development in L. chinense.

Environmentally realistic concentrations of eprinomectin induce phytotoxic and genotoxic effects in Allium cepa

Eprinomectin, a veterinary drug within the family of avermectins, is widely used in the agricultural sector to combat a variety of parasites, mainly nematodes. However, only 10% of the drug is metabolized in the organism, so large quantities of the drug are released into the environment through urine and/or feces. Soil is the first and main environmental compartment to be contaminated by it, and nontargeted organisms can be affected. Thus, the present study aims to evaluate the phytotoxicity (through the evaluation of germination, root development, and germination speed) and genotoxicity (through an assessment of the induction of micronuclei and chromosomal aberrations) of eprinomectin. For the analyses, Allium cepa seeds were germinated in soil contaminated with a range of concentrations of eprinomectin: from 0.5 to 62.5 μg/g for the genotoxicity test and from 0.5 to 128.0 μg/g for the phytotoxicity test. The results showed that seed germination was not affected, but root development was affected at concentrations of 0.5 μg/g, 1.0 μg/g, 4.0 μg/g, 8.0 μg/g, 64.0 μg/g, and 128.0 μg/g, and germination speed was significantly changed at concentrations of 1.0 μg/g, 4.0 μg/g, 16.0 μg/g, 32.0 μg/g, and 64.0 μg/g. Significant differences in the mitotic index and genotoxicity index were observed only at concentrations of 2.5 μg/g and 12.5 μg/g, respectively. Only the 0.5 μg/g concentration did not show significant induction of micronuclei in the meristematic cells, but the damage observed at other concentrations did not persist in F₁ cells. According to the results, eprinomectin is both phytotoxic and genotoxic, so the release of eprinomectin into the environment should be minimized.

AtHB40 modulates primary root length and gravitropism involving CYCLINB and auxin transporters

Gravitropism is a finely regulated tropistic response based on the plant perception of directional cues. Such perception allows them to direct shoot growth upwards, above ground, and root growth downwards, into the soil, anchoring the plant to acquire water and nutrients. Gravity sensing occurs in specialized cells and depends on auxin distribution, regulated by influx/efflux carriers. Here we report that AtHB40, encoding a transcription factor of the homeodomain-leucine zipper I family, was expressed in the columella and the root tip. Athb40 mutants exhibited longer primary roots. Enhanced primary root elongation was in agreement with a higher number of cells in the transition zone and the induction of CYCLINB transcript levels. Moreover, athb40 mutants and AtHB40 overexpressors displayed enhanced and delayed gravitropistic responses, respectively. These phenotypes were associated with altered auxin distribution and deregulated expression of the auxin transporters LAX2, LAX3, and PIN2. Accordingly, lax2 and lax3 mutants also showed an altered gravitropistic response, and LAX3 was identified as a direct target of AtHB40. Furthermore, AtHB40 is induced by AtHB53 when the latter is upregulated by auxin. Altogether, these results indicate that AtHB40 modulates cell division and auxin distribution in the root tip thus altering primary root length and gravitropism.

MITOGEN-ACTIVATED PROTEIN KINASE PHOSPHATASE 1 mediates root sensing of serotonin through jasmonic acid signaling and modulating reactive oxygen species

Serotonin (5-hydroxytryptamine) acts as a neurotransmitter in mammals and is widely distributed in the plant kingdom, where it influences root growth and defense. Mitogen-Activated Protein Kinases (MAPKs) and MAPK phosphatases (MKPs) play critical functions in decoding hormonal signalling, but their possible roles in mediating serotonin responses await investigation. In this report, we unveiled positive roles for the MITOGEN-ACTIVATED PROTEIN KINASE PHOSPHATASE1 (MKP1) in the inhibition of the primary root growth, cell division, meristem structure, and differentiation events in Arabidopsis seedlings. mkp1 mutants were less sensitive to jasmonic acid applications that halted primary root growth in wild-type (WT) plants, and consistently, the neurotransmitter activated the expression of the JASMONATE ZIM-domain (JAZ) proteins JAZ1 and JAZ10, two critical proteins orchestrating jasmonic acid signalling. This effect correlated with exacerbated production of endogenous reactive oxygen species (ROS) in the WT, a process constitutively manifested in mkp1 mutants. These data help to clarify the relationship between serotonin and growth/defense trade-offs, and reveal the importance of the MAPK pathway in root development through ROS production.

Preoperative factors analysis on root development after regenerative endodontic procedures: a retrospective study

Background

Regenerative endodontic procedures (REPs) have achieved clinical success on the immature permanent teeth with pulp necrosis, and can promote root development. However, preoperative factors and their effects on root development of REPs have not been definitely concluded. The aim of this study was to investigate the preoperative factors that may influence the root development of REPs.

Methods

A total of 116 teeth in 110 patients treated with REPs in the Paediatric Dentistry Department and Endodontics Department from 2013 to 2017 were included in this study. Preoperative factors including aetiology, age, diagnosis and initial root morphology were collected retrospectively, and the associations between these factors and root development after REPs were analysed by Fisher's exact test and multivariate logistic regression model.

Results

The overall rate of root development after REPs was 89.7%. The dens evaginatus group showed a higher rate (98.8%) in root development than the trauma group (67.6%) (P < 0.01). There was no significant difference among the different age groups (7–13 years old) or among different diagnoses groups (P > 0.05). And it showed in the trauma group that the teeth with apical foramen sizes larger than 3 mm significantly promoted root development than those smaller than 3 mm (P < 0.01). Multivariate logistic regression indicated that aetiology was significantly correlated with root development of REPs (OR: 0.07, 95% CI 0.007, 0.627, P < 0.05).

Conclusions

The REPs promoted more root developments in the dens evaginatus group than the trauma group, indicating that aetiology may be correlated with the root development of REPs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02412-x.

BSISTER transcription factors directly binds to the promoter of IAA19 and IAA29 genes to up-regulate gene expression and promote the root development

Roots play an important role in the growth and development of plants and auxin participates in regulating plant root development. Some studies have shown that BS (BSISTER) gene (the closest gene of class B gene) is involved in plant root development, but whether BS regulates root development via auxin signaling still not clear. To explore VviBS1 and VviBS2 roles in root development, VviBS1 and VviBS2 were overexpressedin Arabidopsis tt16 mutant and we found that they could restore the phenotype of shorter PR (primary roots) and high density of LR (lateral root) of tt16 compared with the wild type Ws Arabidopsis seedlings. However, the addition of exogenous NAA (naphthalene acetic acid) could not significantly promote the PR length of tt16 Arabidopsis, and the auxin signal transduction of tt16 may be blocked. The expression levels of auxin signal transduction pathway genes in Ws, tt16, p35s:VviBS1 in tt16 and p35s:VviBS2 in tt16 seedlings were detected. It was found that the expression of AtARF2, AtARF12, AtARF14, AtARF15, AtARF20, AtGH3, AtGH3-2 and AtSAUR51 genes in tt16 seedlings was higher than that in Ws, while the expression of AtIAA19 and AtIAA29 in Ws seedlings was higher than that of tt16. More importantly, BS may up regulate AtIAA19 and AtIAA29 expression directly by binding to their promoter. In addition, VviBS1 and VviBS2 also affect seed germination and may regulate leaf yellowing by regulating ethylene synthase. Therefore, our findings reveal a molecular mechanism that BS may modulate root system development via Aux/IAA-based auxin signaling, and provide insight into the BS function in regulation of leaf yellowing.

Plant root development: is the classical theory for auxin-regulated root growth false?

One of the longest standing theories and, therein-based, regulation-model of plant root development, posits the inhibitory action of auxin (IAA, indolylacetic acid) on elongation growth of root cells. This effect, as induced by exogenously supplied IAA, served as the foundation stone for root growth regulation. For decades, auxin ruled the day and only allowed hormonal side players to be somehow involved, or in some way affected. However, this copiously reiterated, apparent cardinal role of auxin only applies in roots immersed in solutions; it vanishes as soon as IAA-supplied roots are not surrounded by liquid. When roots grow in humid air, exogenous IAA has no inhibitory effect on elongation growth of maize roots, regardless of whether it is applied basipetally from the top of the root or to the entire residual seedling immersed in IAA solution. Nevertheless, such treatment leads to pronounced root-borne ethylene emission and lateral rooting, illustrating and confirming thereby induced auxin presence and its effect on the root - yet, not on root cell elongation. Based on these findings, a new root growth regulatory model is proposed. In this model, it is not IAA, but IAA-triggered ethylene which plays the cardinal regulatory role - taking effect, or not - depending on the external circumstances. In this model, in water- or solution-incubated roots, IAA-dependent ethylene acts due to its accumulation within the root proper by inhibited/restrained diffusion into the liquid phase. In roots exposed to moist air or gas, there is no effect on cell elongation, since IAA-triggered ethylene diffuses out of the root without an impact on growth.

Dynamics of cell wall polysaccharides during the elongation growth of rye primary roots

In cells of growing rye roots, xyloglucans and homogalacturonans demonstrate developmental stage specificity, while different xylans have tissue specificity. Mannans, arabinans and galactans are also detected within the protoplast. Mannans form films on sections of fresh material. The primary cell walls of plants represent supramolecular exocellular structures that are mainly composed of polysaccharides. Cell wall properties and architecture differ between species and across tissues within a species. We revised the distribution of cell wall polysaccharides and their dynamics during elongation growth and histogenesis in rye roots using nonfixed material and the spectrum of antibodies. Rye is a member of the Poaceae family and thus has so-called type II primary cell walls, which are supposed to be low in pectins and xyloglucans and instead have arabinoxylans and mixed-linkage glucans. However, rye cell walls at the earliest stages of cell development were enriched with the epitopes of xyloglucans and homogalacturonans. Mixed-linkage glucan, which is often considered an elongation growth-specific polysaccharide in plants with type II cell walls, did not display such dynamics in rye roots. The cessation of elongation growth and even the emergence of root hairs were not accompanied by the disappearance of mixed-linkage glucans from cell walls. The diversity of xylan motifs recognized by different antibodies was minimal in the meristem zone of rye roots, but this diversity increased and showed tissue specificity during root growth. Antibodies specific for xyloglucans, galactans, arabinans and mannans bound the cell content. When rye root cells were cut, the epitopes of xyloglucans, galactans and arabinans remained within the cell content, while mannans developed net-like or film-like structures on the surface of sections.

Autotransplantation of teeth with incomplete root formation: systematic review and meta-analysis

OBJECTIVES

To determine the survival of intentional autotransplantation of developing teeth.

MATERIAL AND METHODS

An electronic search was carried out in the MEDLINE database, Web of Science, and Cochrane Library. The criteria used are the ones described in the PRISMA Declaration. The following MeSH terms were used: ("tooth" [MeSH Terms] OR "tooth" [All Fields]) AND ("transplantation, autologous" [MeSH Terms] OR ("transplantation" [All Fields] AND "autologous" [All Fields]) OR "autologous transplantation" [All Fields] OR "autotransplantation" [All Fields]) AND ("humans" [MeSH Terms]. Randomised clinical trials and prospective and retrospective clinical studies were included.

RESULTS

The meta-analytic study of overall survival included a total of 14 studies, yielding an overall survival rate of 97.9%. In studies with 1-year follow-ups, survival was 98%. The resulting 2-year follow-up rate was 97%, while the 5- and 10-year survival rates were 95.9% and 96.9%, respectively.

CONCLUSIONS

The autotransplantation technique performed in a single-phase and on teeth that have not completed their development is a predictable technique, with a described survival rate at a 2-year follow-up of more than 97%.

CLINICAL RELEVANCE

The technique of dental autotransplantation is considered an important resource for the resolution and rehabilitation of tooth loss in patients, especially in those who are still in a growth period. Moreover, this technique has a low complication rate and a 10-year survival rate of 96.9%. It should therefore be considered a safe and reliable procedure.

Cellular and molecular bases of lateral root initiation and morphogenesis

Lateral root development is essential for the establishment of the plant root system. Lateral root initiation is a multistep process that impacts early primordium morphogenesis and is linked to the formation of a morphogenetic field of pericycle founder cells. Gradual recruitment of founder cells builds this morphogenetic field in an auxin-dependent manner. The complex process of lateral root primordium morphogenesis includes several subprocesses, which are presented in this review. The underlying cellular and molecular mechanisms of these subprocesses are examined.

Advancing root developmental research through single-cell technologies

Single-cell RNA-sequencing has greatly increased the spatiotemporal resolution of root transcriptomics data, but we are still only scratching the surface of its full potential. Despite the challenges that remain in the field, the orderly aligned structure of the Arabidopsis root meristem makes it specifically suitable for lineage tracing and trajectory analysis. These methods will become even more potent by increasing resolution and specificity using tissue-specific single-cell RNA-sequencing and spatial transcriptomics. Feeding multiple single-cell omics data sets into single-cell gene regulatory networks will accelerate the discovery of regulators of root development in multiple species. By providing transcriptome atlases for virtually any species, single-cell technologies could tempt many root developmental biologists to move beyond the comfort of the well-known Arabidopsis root meristem.

Transcriptional Analysis in the Arabidopsis Roots Reveals New Regulators that Link rac-GR24 Treatment with Changes in Flavonol Accumulation, Root Hair Elongation and Lateral Root Density

The synthetic strigolactone (SL) analog, rac-GR24, has been instrumental in studying the role of SLs as well as karrikins because it activates the receptors DWARF14 (D14) and KARRIKIN INSENSITIVE 2 (KAI2) of their signaling pathways, respectively. Treatment with rac-GR24 modifies the root architecture at different levels, such as decreasing the lateral root density (LRD), while promoting root hair elongation or flavonol accumulation. Previously, we have shown that the flavonol biosynthesis is transcriptionally activated in the root by rac-GR24 treatment, but, thus far, the molecular players involved in that response have remained unknown. To get an in-depth insight into the changes that occur after the compound is perceived by the roots, we compared the root transcriptomes of the wild type and the more axillary growth2 (max2) mutant, affected in both SL and karrikin signaling pathways, with and without rac-GR24 treatment. Quantitative reverse transcription (qRT)-PCR, reporter line analysis and mutant phenotyping indicated that the flavonol response and the root hair elongation are controlled by the ELONGATED HYPOCOTYL 5 (HY5) and MYB12 transcription factors, but HY5, in contrast to MYB12, affects the LRD as well. Furthermore, we identified the transcription factors TARGET OF MONOPTEROS 5 (TMO5) and TMO5 LIKE1 as negative and the Mediator complex as positive regulators of the rac-GR24 effect on LRD. Altogether, hereby, we get closer toward understanding the molecular mechanisms that underlay the rac-GR24 responses in the root.

Replantation of a Iatrogenically Avulsed Mandibular Premolar Undergoing Orthodontic Therapy: A 5 Year Follow-Up

The succedaneous permanent teeth develop in close proximity to primary teeth. They can get accidentally luxated or avulsed during the extraction of primary teeth. The purpose of this paper was to describe a case of a 14-year-old boy with an "iatrogenic avulsion" of an immature mandibular second premolar during the extraction of a primary mandibular second molar. The case was managed successfully with replantation technique within 30 minutes of extra oral period and followed up for 5 years. The replanted tooth remained clinically asymptomatic, showed continued root development and eruption and remained vital. This paper had also discussed about the modifications in extraction technique to avoid the iatrogenic avulsion of permanent tooth bud during extraction of primary teeth.

Plant Gravitropism: From Mechanistic Insights into Plant Function on Earth to Plants Colonizing Other Worlds

Gravitropism, the growth of roots and shoots toward or away from the direction of gravity, has been studied for centuries. Such studies have not only led to a better understanding of the gravitropic process itself, but also paved new paths leading to deeper mechanistic insights into a wide range of research areas. These include hormone biology, cell signal transduction, regulation of gene expression, plant evolution, and plant interactions with a variety of environmental stimuli. In addition to contributions to basic knowledge about how plants function, there is accumulating evidence that gravitropism confers adaptive advantages to crops, particularly under marginal agricultural soils. Therefore, gravitropism is emerging as a breeding target for enhancing agricultural productivity. Moreover, research on gravitropism has spawned several studies on plant growth in microgravity that have enabled researchers to uncouple the effects of gravity from other tropisms. Although rapid progress on understanding gravitropism witnessed during the past decade continues to be driven by traditional molecular, physiological, and cell biological tools, these tools have been enriched by technological innovations in next-generation omics platforms and microgravity analog facilities. In this chapter, we review the field of gravitropism by highlighting recent landmark studies that have provided unique insights into this classic research topic while also discussing potential contributions to agriculture on Earth and beyond.

Determination of age reference standards based on mandibular third molar root development in a Ugandan population aged 10-22 years

Background

This study was aimed at establishing age estimates based on distal root development of the mandibular third molar for Ugandans aged 10-22 years. This was a cross-sectional study using orthopantomograms (OPGs) of 671 patients attending the Mulago Hospital Dental Clinic. The patients' chronological age and sex were obtained from either their national identity cards or birth certificates (females; n = 326, 48.6%). Third molar root development was assessed using Demirjian, Goldstein, and Tanner (DGT), modified Demirjian by Solari, Moorrees, Fanning, and Hunt (MFH), and Haavikko methods. Age was summarized using means/standard deviation (SD), medians, and lower and upper quartiles. Sex differences were assessed using Student's t-test.

Results

Crown completion (stage D) and root initiation (stage R_i) were observed at 12.6 years for females and 13.5 years for males (P = 0.02), while complete apex closure occurred at 19.8 for females and 20.1 for males (P = 0.3). There were statistically significant differences in Demirjian root stages E, F, and G and MFH and Haavikko stages R_i, R_1/4, and R_1/2 between the sexes (P < 0.05). The difference in the mean age of root development between females and males ranged between 0.9 year at DGT/MFH root stages D and R_i (13.5-12.6) and 1.4 years at Solari, MFH, and Haavikko root stages F, R_1/4, and R_1/2 (16.3-14.9, 17.1-15.7). No differences were observed between the right and left mandibular molars.

Conclusions

This study provides age reference standards based on third molar root development specific to the Ugandan adolescent and young adult population. The findings can be used to formulate contemporary standards and utilized as reference material to assess third molar maturity for forensic purposes.

Gene Regulatory Network Investigation Using Ordinary Differential Equations

This chapter reviews mathematical models of gene regulation, either as "pure" gene regulatory networks, as signal transduction pathways or as combinations of these. The basic underlying methods are discussed from first principles, relying on rigorous mathematical concepts but with an aim to avoid technical details and focus on the intuitive aspects of this type of mathematical models. After reviewing the principles, some real biological examples are presented to illustrate the practice of modeling, using recent examples from the literature. The proposed examples all arise in the context of plant biology, either at the single cell scale, looking at auxin signaling, or at higher scales, looking at auxin active transport.