Amyloplast is involved in the MIZ1-modulated root hydrotropism

Roots exhibit hydrotropism in response to moisture gradients, with the hydrotropism-related gene Mizu-kussei1 (MIZ1) playing a role in regulating root hydrotropism in an oblique orientation. However, the mechanisms underlying MIZ1-regulated root hydrotropism are not well understood. In this study, we employed obliquely oriented experimental systems to investigate root hydrotropism in Arabidopsis. We found that the miz1 mutant displays reduced root hydrotropism but increased root gravitropism following hydrostimulation, as compared to wild-type plants. Conversely, overexpression of AtMIZ1 leads to enhanced root hydrotropism but decreased root gravitropism following hydrostimulation, as compared to wild-type plants. Using co-immunoprecipitation followed by mass spectrometry (IP-MS), we explored proteins that interact with AtMIZ1, and we identified PGMC1 co-immunoprecipitated with MIZ1 in vivo. Furthermore, the miz1 mutant exhibited higher expression of the PGMC1 gene and increased phosphoglucomutase (PGM) activity, while AtMIZ1 overexpressors resulted in lower expression of the PGMC1 gene, reduced amyloplast amount, and reduced PGM activity in comparison to wild-type roots. In addition, different Arabidopsis natural accessions having difference in their hydrotropic response demonstrated expression level of PGMC1 was negatively correlated with hydrotropic root curvature and AtMIZ1 expression. Our results provide valuable insights into the role of amyloplast in MIZ1-regulated root hydrotropism.

The adsorption-diffusion model and biomimetic simulation reveal the switchable roles of silicon in regulating toxic metal uptake in rice roots

Soil contamination by heavy metals has become a serious threat to global food security. The application of silicon (Si)-based materials is a simple and economical method for producing safe crops in contaminated soil. However, the impact of silicon on the heavy-metal concentration in plant roots, which are the first line in the chain of heavy-metal entering plants and causing stress and the main site of heavy-metal deposition in plants, remains puzzling. We proposed a process-based model (adsorption-diffusion model) to explain the results of a collection of 28 experiments on alleviating toxic metal stress in plants by Si. Then we evaluated the applicability of the model in Si-mitigated trivalent chromium (Cr[III]) stress in rice, taking into account variations in experimental conditions such as Cr(III) concentration, stress duration, and Si concentration. It was found that the adsorption-diffusion model fitted the experimental data well (R2 > 0.9). We also verified the binding interaction between Si and Cr in the cell wall using SEM-EDS and XPS. In addition, we designed a simplified biomimetic device that simulated the Si in cell wall to analyze the dual-action switch of Si from increasing Cr(III) adsorption to blocking Cr(III) diffusion. We found that the adsorption of Cr(III) by Si decreased from 58% to 7% as the total amount of Cr(III) increased, and finally the diffusion blocking effect of Si dominated. This study deepens our understanding of the role of Si in mitigating toxic metal stress in plants and is instructive for the research and use of Si-based materials to improve food security.

Sesquiterpenes of the ectomycorrhizal fungus Pisolithus microcarpus alter root growth and promote host colonization

Trees form symbioses with ectomycorrhizal (ECM) fungi, maintained in part through mutual benefit to both organisms. Our understanding of the signaling events leading to the successful interaction between the two partners requires further study. This is especially true for understanding the role of volatile signals produced by ECM fungi. Terpenoids are a predominant class of volatiles produced by ECM fungi. While several ECM genomes are enriched in the enzymes responsible for the production of these volatiles (i.e., terpene synthases (TPSs)) when compared to other fungi, we have limited understanding of the biochemical products associated with each enzyme and the physiological impact of specific terpenes on plant growth. Using a combination of phylogenetic analyses, RNA sequencing, and functional characterization of five TPSs from two distantly related ECM fungi (Laccaria bicolor and Pisolithus microcarpus), we investigated the role of these secondary metabolites during the establishment of symbiosis. We found that despite phylogenetic divergence, these TPSs produced very similar terpene profiles. We focused on the role of P. microcarpus terpenes and found that the fungus expressed a diverse array of mono-, di-, and sesquiterpenes prior to contact with the host. However, these metabolites were repressed following physical contact with the host Eucalyptus grandis. Exposure of E. grandis to heterologously produced terpenes (enriched primarily in γ -cadinene) led to a reduction in the root growth rate and an increase in P. microcarpus-colonized root tips. These results support a very early putative role of fungal-produced terpenes in the establishment of symbiosis between mycorrhizal fungi and their hosts.

Mechanisms for plant growth promotion activated by Trichoderma in natural and managed terrestrial ecosystems

Trichoderma spp. are free-living fungi present in virtually all terrestrial ecosystems. These soil fungi can stimulate plant growth and increase plant nutrient acquisition of macro- and micronutrients and water uptake. Generally, plant growth promotion by Trichoderma is a consequence of the activity of potent fungal signaling metabolites diffused in soil with hormone-like activity, including indolic compounds as indole-3-acetic acid (IAA) produced at concentrations ranging from 14 to 234 μg l-1, and volatile organic compounds such as sesquiterpene isoprenoids (C15), 6-pentyl-2H-pyran-2-one (6-PP) and ethylene (ET) produced at levels from 10 to 120 ng over a period of six days, which in turn, might impact plant endogenous signaling mechanisms orchestrated by plant hormones. Plant growth stimulation occurs without the need of physical contact between both organisms and/or during root colonization. When associated with plants Trichoderma may cause significant biochemical changes in plant content of carbohydrates, amino acids, organic acids and lipids, as detected in Arabidopsis thaliana, maize (Zea mays), tomato (Lycopersicon esculentum) and barley (Hordeum vulgare), which may improve the plant health status during the complete life cycle. Trichoderma-induced plant beneficial effects such as mechanisms of defense and growth are likely to be inherited to the next generations. Depending on the environmental conditions perceived by the fungus during its interaction with plants, Trichoderma can reprogram and/or activate molecular mechanisms commonly modulated by IAA, ET and abscisic acid (ABA) to induce an adaptative physiological response to abiotic stress, including drought, salinity, or environmental pollution. This review, provides a state of the art overview focused on the canonical mechanisms of these beneficial fungi involved in plant growth promotion traits under different environmental scenarios and shows new insights on Trichoderma metabolites from different chemical classes that can modulate specific plant growth aspects. Also, we suggest new research directions on Trichoderma spp. and their secondary metabolites with biological activity on plant growth.

Assessment of the root and canal morphology in the permanent dentition of Saudi Arabian population using cone beam computed and micro-computed tomography - a systematic review

INTRODUCTION

Root canal treatment procedures require a thorough understanding of root and canal anatomy. The purpose of this systematic review was to examine the morphological differences of teeth root and their canals assessed using cone-beam computed and micro-computed tomography in Saudi Arabian population.

METHODOLOGY

An electronic search was conducted in PubMed / Medline, Scopus, Google Scholar, and Web of Science databases until January 2023 to retrieve related studies. "Root canal morphology," "Saudi Arabia," "Micro-CT," and "cone-beam computed tomography" were used as keywords. A modified version of previously published risk of bias assessment tool was used to determine the quality assessment of included studies.

RESULTS

The literature search revealed 47 studies that matched the criteria for inclusion, out of which 44 studies used cone beam computed tomography (CBCT) and three were micro-computed tomography (micro-CT) studies. According to the modified version of risk of bias assessment tool, the studies were categorized as low, moderate, and high risk of bias. A total of 47,612 samples were included which comprised of either maxillary teeth (5,412), or mandibular teeth (20,572), and mixed teeth (21,327). 265 samples were used in micro-CT studies while 47,347 teeth samples were used in CBCT studies. Among the CBCT studies, except for three, all the studies were retrospective studies. Frequently used imaging machine and software were 3D Accuitomo 170 and Morita's i-Dixel 3D imaging software respectively. Minimum and maximum voxel sizes were 75 and 300 μm, Vertucci's classification was mostly used to classify the root canal morphology of the teeth. The included micro-CT studies were in-vitro studies where SkyScan 1172 X-ray scanner was the imaging machine with pixel size ranging between 13.4 and 27.4 μm. Vertucci, Ahmed et al. and Pomeranz et al. classifications were applied to classify the root canal morphology.

CONCLUSION

This systematic review revealed wide variations in root and canal morphology of Saudi population using high resolution imaging techniques. Clinicians should be aware of the common and unusual root and canal anatomy before commencing root canal treatment. Future micro-CT studies are needed to provide additional qualitative and quantitative data presentations.

Precipitation- rather than temperature-driven pattern in belowground biomass and root:shoot ratio across the Qinghai-Tibet Plateau

The Qinghai-Tibet Plateau faces dramatic global change, which can greatly affect its plant growth, biomass accumulation, and carbon cycling. However, it is still unclear how belowground plant biomass, which is the major part of vegetation biomass on the plateau, changes with different environmental factors, impeding accurate prediction of ecosystem carbon cycling under future global change scenarios. To reveal the patterns of belowground biomass and root:shoot ratio with environmental factors in different vegetation types on the Qinghai-Tibet Plateau, we synthesized data for 158 sites from 167 publications, including 585 and 379 observations for above- and below-ground biomass, respectively. Data on temperature, precipitation, soil nitrogen content, evapotranspiration and solar radiation were collected from open databases. The results showed that precipitation, rather than temperature, was closely associated with other environmental factors including soil N and solar radiation. Also, both above- and below-ground biomass significantly increased with annual precipitation and its related environmental factors, while elevation-related coldness only slightly decreased aboveground biomass. In addition, the positive effect of precipitation on belowground biomass is more obvious in higher elevations (colder areas). As a result, root:shoot ratio significantly increased with precipitation in colder areas but not in warmer areas. Finally, the positive relationship between biomass and precipitation was stronger for dryer steppes than for wetter meadows and shrublands. Our findings indicate that precipitation, as well as the associated nitrogen availability and solar radiation, together are more important drivers than temperature for ecosystem productivity and biomass allocation on the Qinghai-Tibet Plateau. Given the heterogeneous trend of precipitation change on the plateau, productivity response to global change can be highly variable across different regions and vegetation types, which can consequently impact soil carbon dynamics and regional carbon cycling.

ULTRAPETALAs in action: Unraveling their role in root development

The epigenetic complex Trithorax (TrxG) regulates gene transcription through post-translational histone modifications and is involved in a wide range of developmental processes. ULTRAPETALA1 (ULT1) is a SAND domain plant-exclusive TrxG protein that regulates the H3K4me3 active mark to counteract PcG repression. ULT1 has been identified to be involved in multiple tissue-specific processes. In the Arabidopsis root, ULT1 is required to maintain the stem cell niche, a role that is independent of the histone methyltransferase ATX1. Here we show the contribution of ULT2 in the maintenance of root stem cell niche. We also analyzed the gene expression in the ult1, ult2, and ult1ult2 mutants, evidencing three ways in which ULT1 and ULT2 regulate gene expression, one of them, where ULT1 or ULT2 regulate specific genes each, another where ULT1 and ULT2 act redundantly, as well as a regulation that requires of ULT1 and ULT2 together, supporting a coregulation, never reported. Furthermore, we also evidenced the participation of ULT1 in transcriptional repression synergically with CLF, a key histone methyltransferase of PcG.

Systematic review and network meta-analysis of restorative therapy and adhesive strategies in root caries lesions

AIM

This systematic review and network meta-analysis (NMA) aimed to establish a clinically relevant hierarchy of the different adhesive and/or restorative approaches to restore cavitated root caries lesions through the synthesis of available evidence.

MATERIALS AND METHODS

A systematic search was conducted in Medline/Web of Science/Embase/ Cochrane Library/Scopus/grey literature. RCTs investigating ≥2 restorative strategies (restorative /adhesive materials) for root caries lesions in adult patients were included. Risk of bias within studies was assessed (Cochrane_RoB-2) and the primary outcome was survival rate of restorations at different follow-up times (6-/12-/24-months). Network meta-analyses were conducted using a random effects model stratified by follow-up times. I2-statistics assessed the ratio of true to total variance in the observed effects. All available combinations of adhesives (1-SE: one-step self-etch; 2-3ER: two-/three-step etch-and-rinse) and restorative materials (conventional composite (CC) as well as conventional and resin-modified glass ionomer cements (GIC, RMGIC)) were included. Risk of bias across studies and confidence in NMA (CINeMA) were assessed.

RESULTS

547 studies were identified and nine were eligible for the NMA. In total, 1263 root caries lesions have been restored in 473 patients in the included clinical trials. Patients involved were either healthy (n = 6 trials), living in nursing homes (n = 1 trial) or received head-and-neck radiotherapy (n = 2 trials). There was statistically weak evidence to favour either of material/material combination regarding the survival rate. A tendency for higher survival rate (24-months) was observed for 2-3ER/CC (OR24mths 2.65; 95%CI=1.45/4.84) as well as RMGIC (OR24mths 2.05; 95%CI=1.17/3.61) compared to GIC. These findings were though not statistically significant and confidence of the NMA was low.

CONCLUSION

An evidence-based choice of restorative strategy for managing cavitated root caries lesions is currently impossible. There is a clear need for more standardised, well-designed RCTs evaluating the retention rate of root caries restoration approaches.

Dynamic changes in calcium signals during root gravitropism

Gravitropism is a vital mechanism through which plants adapt to their environment. Previous studies indicated that Ca2+ may play an important role in plant gravitropism. However, our understanding of the calcium signals in root gravitropism is still largely limited. Using a vertical stage confocal and transgenic Arabidopsis R-GECO1, our data showed that gravity stimulation enhances the occurrence of calcium spikes and increases the Ca2+ concentration in the lower side of the root cap. Furthermore, a close correlation was observed in the asymmetry of calcium signals with the inclination angles at which the roots were oriented. The frequency of calcium spikes on the lower side of 90°-rotated root decreases rapidly over time, whereas the asymmetric distribution of auxin readily strengthens for up to 3 h, indicating that the calcium spikes, promoted by gravity stimulation, may precede auxin as one of the early signals. In addition, the root gravitropism of starchless mutants is severely impaired. Correspondingly, no significant increase in calcium spike occurrence was observed in the root caps of these mutants within 15 min following a 90° rotation, indicating the involvement of starch grains in the formation of calcium spikes. However, between 30 and 45 min after a 90° rotation, asymmetric calcium spikes were indeed observed in the root of starchless mutants, suggesting that starch grains are not indispensable for the formation of calcium spikes. Besides, co-localization analysis suggests that the ER may function as calcium stores during the occurrence of calcium spikes. These findings provide further insights into plant gravitropism.

Nutrient supply systems and their effect on the performance of the Nile Tilapia (Oreochromis niloticus) and Lettuce (Lactuca sativa) plant integration system

The main aim of this work is to study the effect of different nutrient supply systems and their effect on the performance of the Nile Tilapia (Oreochromis niloticus) and Lettuce (Lactuca sativa var. crispa) plant integration system. To achieve that, five treatments having different culture systems (T1: Aquaculture (control), T2: Hydroponics (standard requirement: N = 210, P = 31, K = 234, Mg = 48, Ca = 200, S = 64, Fe = 14, Mn = 0.5, Zn = 0.05, B = 0.5, Cu = 0.02 and Mo = 0.01 ppm), T3: Aquaponics without nutrients addition, T4: Aquaponics with supplementary nutrients (KNO3, 101 g L-1, KH2PO4, 136 g L-1, Ca(NO3)2, 236 g L-1, MgSO4, 246 g L-1, K2SO4, 115 g L-1 and chelates for trace elements) in water (EC is 800 ppm) and T5: Aquaponics with supplementary nutrients spray on plants) were carried out. The previous systems were operated at three flow rates, namely, 1.0, 1.5 and 2.0 L h-1 plant-1. The various water quality parameters, plant growth and fish growth were studied. The result indicated that the highest values of N, P, k, Ca and Mg consumption rate were found with T2 and 1.5 L h-1 plant-1 of flow rate. The root length, fresh and dry of shoot and root for lettuce plants grown in T2 system was better than those grown in different culture system (T3, T4 and T5). Different culture systems showed significant effect on fish growth in terms of weight gain, specific growth rate and feed efficiency ratio. Higher growth rate was observed in treatment T3 as compared to other treatments. The production costs ranged from 2820.5 to 4885.4 LE ($ = 30.92 LE) for all culture systems.

Identification of genetics and hormonal factors involved in Quercus robur root growth regulation in different cultivation system

Understanding the molecular processes and hormonal signals that govern root growth is of paramount importance for effective forest management. While Arabidopsis studies have shed light on the role of the primary root in root system development, the structure of root systems in trees is considerably more intricate, posing challenges to comprehend taproot growth in acorn-sown and nursery-cultivated seedlings. In this study, we investigated Quercus robur seedlings using rhizotrons, containers, and transplanted containers to rhizotrons, aiming to unravel the impact of forest nursery practices on processes governing taproot growth and root system development. Root samples were subjected to RNA-seq analysis to identify gene expression patterns and perform differential gene expression and phytohormone analysis. Among studied cultivation systems, differentially expressed genes (DEGs) exhibited significant diversity, where the number of co-occurring DEGs among cultivation systems was significantly smaller than the number of unique DEGs in different cultivation systems. Moreover, the results imply that container cultivation triggers the activation of several genes associated with linolenic acid and peptide synthesis in root growth. Upon transplantation from containers to rhizotrons, rapid enhancement in gene expression occurs, followed by gradual reduction as root growth progresses, ultimately reaching a similar expression pattern as observed in the taproot of rhizotron-cultivated seedlings. Phytohormone analysis revealed that taproot growth patterns under different cultivation systems are regulated by the interplay between auxin and cytokinin concentrations. Moreover, the diversification of hormone levels within the root zone and cultivation systems allows for taproot growth inhibition and prompt recovery in transplanted seedlings. Our study highlights the crucial role of hormone interactions during the early stages of taproot elongation, influencing root system formation across.

Effect of sodium hypochlorite temperature and concentration on the fracture resistance of root dentin

BACKGROUND

Sodium hypochlorite (NaOCl) is the most efficient root canal irrigant to date. The aim of this study was to compare the effect of NaOCl used at different temperatures and concentrations on the compressive strength of root dentin.

MATERIALS AND METHODS

Seventy-two extracted human single-canaled straight roots of comparable size and length were selected and randomly divided into six groups (n = 12): Group (A) served as a control with unprepared canals. The other groups were instrumented with rotary ProTaper Universal files up to size F3. Group (B) was irrigated with 1% NaOCl at room temperature, Group (C) with 1% NaOCl heated to 70 °C, Group (D) with 5.25% NaOCl at room temperature, and Group (E) with 5.25% NaOCl heated to 70 °C. Saline was used in Group (F). The roots were sectioned into 2-mm-thick disks that underwent compression testing using a universal testing machine. Data were analyzed using one-way ANOVA and post hoc Tukey tests. The significance level was set at p ≤ 0.05.

RESULTS

A total of 255 disks were tested. The control group showed the highest compressive strength (p = 0.0112). However, this did not differ significantly from that of heated (p = 0.259) or unheated (p = 0.548) 1% NaOCl. There were no statistically significant differences between the groups of instrumented teeth.

CONCLUSION

Within the conditions of this study, irrigation with NaOCl at different concentrations and temperatures during root canal preparation did not affect the compressive strength of root dentin.

CLINICAL RELEVANCE

This study demonstrates that the use of NaOCl as a root canal irrigant is not associated with a clinically relevant decrease in root compressive strength, especially when compared to saline.

Micro computed tomography (Micro-CT) characterization of root and root canal morphology of mandibular first premolars: a systematic review and meta-analysis

INTRODUCTION

Mandibular first premolars are familiar with their varied root canal morphology, causing difficulties and challenges for successful endodontic procedures. This systematic review and meta-analysis aim to study the characterization of root and canal morphology of the first mandibular premolar using micro-computed tomography.

METHODOLOGY

The literature search was conducted using electronic web databases like PubMed, Scopus, ScienceDirect and Cochrane with the chosen MeSH key words and data was retrieved until May 2023. Further to perform the statistical analysis, R v 4.3.1 software with "meta", 'metafor" "metaviz" " ggplot2" package was used, and results were represented by odds ratios (OR) and the percentage of forest plots along a 95 per cent confidence interval (CI).

RESULTS

The total number of studies meeting the inclusion criteria was 13; these studies were conducted on mandibular first premolar using Micro-CT; the total sample size was 1817. To scan the sample, an X-ray micro-focus CT system (Siemens Inveon CT, Erlangen, Germany) was used in four studies and seven different machines were used in the respective studies. Mimics 10.01 software (Materialize, Leuven, Belgium) and NRecon v.1.6.9 software (Bruker, Kontich, Belgium) were commonly operated. The minimum and maximum voxel size ranges between 11.94 and 50 μm. Vertucci's classification was frequently used (9), while one study applied Ahmed et al. and Vertucci's classification.

CONCLUSION

This systematic review provides essential information about the root and canal configurations, radicular grooves, accessory canals, and apical foramina through Micro-CT, aiming to improve the accuracy of endodontic treatment and help practitioners.

Functional characterization of GhNAC2 promoter conferring hormone- and stress-induced expression: a potential tool to improve growth and stress tolerance in cotton

The GhNAC2 transcription factor identified from G. herbaceum improves root growth and drought tolerance through transcriptional reprogramming of phytohormone signaling. The promoter of such a versatile gene could serve as an important genetic engineering tool for biotechnological application. In this study, we identified and characterized the promoter of GhNAC2 to understand its regulatory mechanism. GhNAC2 transcription factor increased in root tissues in response to GA, ethylene, auxin, ABA, mannitol, and NaCl. In silico analysis revealed an overrepresentation of cis-regulatory elements associated with hormone signaling, stress responses and root-, pollen-, and seed-specific promoter activity. To validate their role in GhNAC2 function/regulation, an 870-bp upstream regulatory sequence was fused with the GUS reporter gene (uidA) and expressed in Arabidopsis and cotton hairy roots for in planta characterization. Histochemical GUS staining indicated localized expression in root tips, root elongation zone, root primordia, and reproductive tissues under optimal growth conditions. Mannitol, NaCl, auxin, GA, and ABA, induced the promoter-driven GUS expression in all tissues while ethylene suppressed the promoter activity. The results show that the 870 nt fragment of the GhNAC2 promoter drives root-preferential expression and responds to phytohormonal and stress signals. In corroboration with promoter regulation, GA and ethylene pathways differentially regulated root growth in GhNAC2-expressing Arabidopsis. The findings suggest that differential promoter activity governs the expression of GhNAC2 in root growth and stress-related functions independently through specific promoter elements. This multifarious promoter can be utilized to develop yield and climate resilience in cotton by expanding the options to control gene regulation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-024-01411-2.

Assessing Temperature Responses in Roots

Due to global warming, it is important to understand how plants respond to high ambient temperature. Plant growth responses to high ambient temperature are termed thermomophogenesis and have been explored for more than a decade. However, this was mostly focused on the above-ground part of plants, the shoot. In this chapter, we describe a simple method to assess root growth phenotype to high ambient temperatures. In principle, this protocol can be applied for any other treatments to test overall seedling growth.

Monitoring Xylem Transport in Arabidopsis thaliana Seedlings Using Fluorescent Dyes

Fluorescent dyes are often used to observe transport mechanisms in plant vascular tissues. However, it has been technically challenging to apply fluorescent dyes on roots to monitor xylem transport in vivo. Here, we present a fast, noninvasive, and high-throughput protocol to monitor xylem transport in seedlings. Using the fluorescent dyes 5(6)-carboxyfluorescein diacetate (CFDA) and Rhodamine WT, we were able to observe xylem transport on a cellular level in Arabidopsis thaliana roots. We describe how to apply these dyes on primary roots of young seedlings, how to monitor root-to-shoot xylem transport, and how to measure xylem transport velocity in roots. Moreover, we show that our protocol can also be applied to lateral roots and grafted seedlings to assess xylem (re)connection. Altogether, these techniques are useful for investigating xylem functionality in diverse experimental setups.

Recovery of root hydrotropism in miz1 mutant by eliminating root gravitropism

Mizu-kussei1 (MIZ1) plays a crucial role in root hydrotropism, but it is still unclear whether auxin-mediated gravitropism is involved in MIZ1-modulated root hydrotropism. This study aimed to investigate whether the hydrotropism of the Arabidopsis miz1 mutants could be restored through pharmacological inhibition of auxin transport or genetic modification in root gravitropism. Our findings indicate that the hydrotropic defects of miz1 mutant can be partly recovered by using an auxin transport inhibitor. Furthermore, miz1/pin2 double mutants exhibit more pronounced defects in root gravitropism compared to the wild type, while still displaying a normal hydrotropic response similar to the wild type. These results suggest that the elimination of gravitropism enables miz1 roots to become hydrotropically responsive to moisture gradients.

Comparative physiological and transcriptomic analysis of two salt-tolerant soybean germplasms response to low phosphorus stress: role of phosphorus uptake and antioxidant capacity

BACKGROUND

Phosphorus (P) and salt stress are common abiotic stressors that limit crop growth and development, but the response mechanism of soybean to low phosphorus (LP) and salt (S) combined stress remains unclear.

RESULTS

In this study, two soybean germplasms with similar salt tolerance but contrasting P-efficiency, A74 (salt-tolerant and P-efficient) and A6 (salt-tolerant and P-inefficient), were selected as materials. By combining physiochemical and transcriptional analysis, we aimed to elucidate the mechanism by which soybean maintains high P-efficiency under salt stress. In total, 14,075 differentially expressed genes were identified through pairwise comparison. PageMan analysis subsequently revealed several significantly enriched categories in the LP vs. control (CK) or low phosphorus + salt (LPS) vs. S comparative combination when compared to A6, in the case of A74. These categories included genes involved in mitochondrial electron transport, secondary metabolism, stress, misc, transcription factors and transport. Additionally, weighted correlation network analysis identified two modules that were highly correlated with acid phosphatase and antioxidant enzyme activity. Citrate synthase gene (CS), acyl-coenzyme A oxidase4 gene (ACX), cytokinin dehydrogenase 7 gene (CKXs), and two-component response regulator ARR2 gene (ARR2) were identified as the most central hub genes in these two modules.

CONCLUSION

In summary, we have pinpointed the gene categories responsible for the LP response variations between the two salt-tolerant germplasms, which are mainly related to antioxidant, and P uptake process. Further, the discovery of the hub genes layed the foundation for further exploration of the molecular mechanism of salt-tolerant and P-efficient in soybean.

EasyClick: an improved system for confocal microscopy of live roots with a user-optimized sample holder

MAIN CONCLUSION

We describe a user-optimized sample holder EasyClick for medium-sized plants that reduces root side movements and thus greatly extends the duration of live cell confocal microscopy. Preparation and mounting of the samples are key factors for successful live cell microscopy. To acquire biologically relevant data, it is necessary to minimize stress and avoid physical damage to plant tissues during the installation of the sample into the microscope. This is challenging, particularly when the whole plant is mounted as the living sample needs to be properly anchored in the microscopic system to obtain high-quality and high-resolution data. Here, we present a user-optimized sample holder EasyClick for live cell inverted confocal microscopic analysis of plant roots with diameters from 0.3 to 0.7 mm. The EasyClick holder was tested on an inverted confocal microscope using germinating plants of several cereals. Nevertheless, it can be directly used on other types of inverted microscopes from various producers and on different plant species. The EasyClick holder effectively restricts root lateral and vertical movements. This greatly improves the conditions for time-lapse microscopy of the samples of interest.

Ethylene and ROS mediate root growth inhibition induced by the endocrine disruptor bisphenol A (BPA)

Bisphenol A (BPA) functions as a detrimental substance that disrupts the endocrine system in animals while also impeding the growth and development of plants. In our previous study, we demonstrated that BPA hinders the growth of roots in Arabidopsis by diminishing cell division and elongation, which is ascribed to the increased accumulation and redistribution of auxin. Here, we examined the mediation of ROS and ethylene in BPA-induced auxin accumulation and root growth inhibition. BPA enhanced ROS levels, and ROS increased auxin contents but reduced cell division activity and the expression of EXPA8 involved in root elongation. ROS scavenger treatment reversed BPA-triggered root growth retardation, auxin accumulation, and cell division inhibition. In addition, BPA induced ethylene, and ethylene synthesis inhibitor treatment reversed BPA-triggered root growth retardation and auxin accumulation. Taken together, ROS and ethylene are involved in BPA-inhibited cell elongation and cell division by mediating auxin accumulation and redistribution.

Tunable recurrent priming of lateral roots in Arabidopsis: More than just a clock?

Lateral root (LR) formation in Arabidopsis is a continuous, repetitive, post-embryonic process regulated by a series of coordinated events and tuned by the environment. It shapes the root system, enabling plants to efficiently explore soil resources and adapt to changing environmental conditions. Although the auxin-regulated modules responsible for LR morphogenesis and emergence are well documented, less is known about the initial priming. Priming is characterised by recurring peaks of auxin signalling, which, once memorised, earmark cells to form the new LR. We review the recent experimental and modelling approaches to understand the molecular processes underlying the recurring LR formation. We argue that the intermittent priming of LR results from interweaving the pattern of auxin flow and root growth together with an oscillatory auxin-modulated transcriptional mechanism and illustrate its long-range sugar-mediated tuning by light.

Lipid profiling reveals Leymus Chinensis root insensitivity to Ca limitation

BACKGROUND

Leymus chinensis (L. chinensis) is a perennial native forage grass widely distributed in the steppe of Inner Mongolia as the dominant species. Calcium (Ca) is an essential mineral element important for plant adaptation to the growth environment. Ca limitation was previously shown to strongly inhibit Arabidopsis (Arabidopsis thaliana) seedling growth and disrupt plasma membrane stability and selectivity, increasing fluid-phase-based endocytosis and contents of all major membrane lipids.

RESULTS

In this study, we investigated the significance of Ca for L. chinensis growth and membrane stability relative to Arabidopsis. Our results showed that Ca limitation did not affect L. chinensis seedling growth and endocytosis in roots. Moreover, the plasma membrane maintained high selectivity. The lipid phosphatidylcholine (PC): phosphatidylethanolamine (PE) ratio, an indicator of the membrane stability, was five times higher in L. chinensis than in Arabidopsis. Furthermore, in L. chinensis, Ca limitation did not affect the content of any major lipid types, decreased malondialdehyde (MDA) content, and increased superoxide dismutase (SOD) activity, showing an opposite pattern to that in Arabidopsis. L. chinensis roots accumulated higher contents of PC, phosphatidylinositol (PI), monogalactosyldiacylglycerol (MGDG), phosphatidylglycerol (PG), cardiolipin (CL), digalactosyldiacylglycerol (DGDG), and lysophosphatidylcholine (LPC) but less phosphatidylethanolamine (PE), diacylglycerol (DAG), triacylglycerolv (TAG), phosphatidylserine (PS), lysobisphosphatidic acids (LPAs), lysophosphatidylethanolamine (LPE), and lysophosphatidylserine (LPS) than Arabidopsis roots. Moreover, we detected 31 and 66 unique lipids in L. chinensis and Arabidopsis, respectively.

CONCLUSIONS

This study revealed that L. chinensis roots have unique membrane lipid composition that was not sensitive to Ca limitation, which might contribute to the wider natural distribution of this species.

Rhizocompartmental microbiomes of arrow bamboo (Fargesia nitida) and their relation to soil properties in Subalpine Coniferous Forests

Arrow bamboo (Fargesia nitida) is a pioneer plant in secondary forest succession in the Sichuan Province mountains. To comprehensively investigate the microbial communities and their functional variations in different rhizocompartments (root endosphere, rhizosphere, and root zone) of arrow bamboo (Fargesia nitida), a high-throughput metagenomic study was conducted in the present study. The results showed that the abundances of the dominant bacterial phyla Proteobacteria and Actinobacteria in the bamboo root endosphere were significantly lower than those in the rhizosphere and root zones. In contrast, the dominant fungal phyla, Ascomycota and Basidiomycota, showed the opposite tendency. Lower microbial diversity, different taxonomic composition and functional profiles, and a greater abundance of genes involved in nitrogen fixation (nifB), cellulose degradation (beta-glucosidase), and cellobiose transport (cellulose 1, 4-beta-cellobiosidase) were found in the bamboo root endosphere than in the other rhizocompartments. Greater soil total carbon, total nitrogen, NH4+-N, microbial biomass carbon, and greater activities of invertase and urease were found in the bamboo root zone than in the adjacent soil (spruce root zone). In contrast, the soil microbial community and functional profiles were similar. At the phylum level, invertase was significantly related to 31 microbial taxa, and the effect of NH4+-N on the microbial community composition was greater than that of NO3--N. The soil physicochemical properties and enzyme activities were significantly correlated with microbial function. These results indicate that the root endosphere microbiomes of arrow bamboo were strongly selected by the host plant, which caused changes in the soil nutrient properties in the subalpine coniferous forest.

The meniscal extrusion index is a reliable indirect sign of different meniscal lesion patterns: a classification based on percentage of meniscal extrusion

PURPOSE

This study's goal is to propose a straightforward classification system based on the MEI (Meniscal Extrusion Index), a measure of meniscal extrusion, that relates to various meniscal lesion patterns and has clinical and biomechanical significance. The study's secondary goal is to determine whether the standard 3 mm meniscal extrusion parameter still has value by correlating the MEI with it.

METHODS

1350 knee MRIs that were performed over the course of 2 years made up the study cohort. Following the application of inclusion and exclusion criteria, 200 of those patients were qualified to participate in the study. All the measurements examined for this study underwent an interobserver reliability test.

RESULTS

In the 1350 MRIs that were examined for this study, meniscal extrusion of any grade was present 18.9% of the time. The use of the MEI revealed three groups of patients: those with a MEI < 20%, who are likely para-physiological; those with a MEY between 20% and 40%, who are in a grey area; and those with a MEY > 40%, who have lesions that are impairing the proper meniscal function. According to the authors' findings, the percentage of meniscal extrusion did not correlate with the finite number (3 mm), making the 3 mm parameter an unreliable evaluation method.

CONCLUSIONS

This study is clinically relevant, because it proposes a simple and reproducible classification of meniscal extrusion that may aid in evaluating the severity of an extrusion and help in the diagnosis of lesions that might be difficult to identify on MRI.

LEVEL OF EVIDENCE

Level IV.

MIZ1 acts downstream of PGM1 in regulating root hydrotropism

The MIZ1 play an important role in root hydrotropism. However, the relationship between MIZ1-regulated hydrotropism and amyloplast-mediated gravitropism remain largely unclear. Here, we generated the miz1/pgm1 double mutants by crossing the non-hydrotropic miz1 mutant with the amyloplast-defective pgm1 mutant, which lacks gravitropic response. Our results showed that the miz1/pgm1 mutants exhibited a significant reduction in amyloplast and gravitropic bending, while maintaining a similar ahydrotropic phenotype as the miz1 single mutant. These findings suggest that MIZ1 plays a role in hydrotropism downstream of PGM1. Understanding the mechanisms of interaction between hydrotropism and gravitropism is crucial for comprehending the rooting patterns of plants in natural conditions. The counteracting relationship between root hydrotropism and gravitropism in the miz1 mutant should receive attention in this field, particularly considering the interference from gravitropism on Earth.

Pulsed electric field treatment of seeds altered the endophytic bacterial community and promotes early growth of roots in buckwheat

BACKGROUND

Endophytic bacteria provide nutrients and stimulate systemic resistance during seed germination and plant growth and development, and their functional properties in combating various stresses make them a powerful tool in green agricultural production. In this paper we explored the function of the endophyte community in buckwheat seeds in order to provide a theoretical basis for the application and scientific research of endophytes in buckwheat cultivation. We used pulsed electric field (PEF) technology to treat buckwheat seeds, monitored the effect of high-voltage pulse treatment on buckwheat seed germination, and analyzed the diversity of endophytic bacteria in buckwheat seeds using the amplicon sequencing method.

RESULTS

PEF treatment promoted root development during buckwheat seed germination. A total of 350 Operational taxonomic units (OTUs) that were assigned into 103 genera were obtained from control and treatment groups using 16SrRNA amplicon sequencing technology. Additionally, PEF treatment also caused a significant decrease in the abundance of Actinobacteria, Proteobacteria, and Bacteroidetes. The abundance of 28 genera changed significantly as well: 11 genera were more abundant, and 17 were less abundant. The number of associated network edges was reduced from 980 to 117, the number of positive correlations decreased by 89.1%, and the number of negative correlations decreased by 86.6%.

CONCLUSION

PEF treatment promoted early root development in buckwheat and was able to alter the seed endophytic bacterial community. This study thus makes a significant contribution to the field of endophyte research and to the application of PEF technology in plant cultivation.

Systems biology of root development in Populus: Review and perspectives

The root system of plants consists of primary, lateral, and adventitious roots (ARs) (aka shoot-born roots). ARs arise from stem- or leaf-derived cells during post-embryonic development. Adventitious root development (ARD) through stem cuttings is the first requirement for successful establishment and growth of planted trees; however, the details of the molecular mechanisms underlying ARD are poorly understood. This knowledge is important to both basic plant biology and because of its necessary role in the successful propagation of superior cultivars of commercial woody bioenergy crops, like poplar. In this review article, the molecular mechanisms that control both endogenous (auxin) and environmentally (nutrients and microbes) regulated ARD and how these systems interact to control the rooting efficiency of poplar trees are described. Then, potential future studies in employing integrated systems biology approaches at cellular resolutions are proposed to more precisely identify the molecular mechanisms that cause AR. Using genetic transformation and genome editing approaches, this information can be used for improving ARD in economically important plants for which clonal propagation is a requirement.

Correlation of various dental parameters of mandibular first molar with age, body weight and breed in healthy dogs

The aim of this study was to investigate the relationship of different radiographic parameters of mandibular first molar with respect to age, body weight and breed in healthy dogs. Overall, 50 dogs with the age from 5 to 156 months and body weight from 6.00 to 45.00 kg of various breeds were made the subject of study. Animals were categorized into different groups based on age, body weight and breed. A new dental parameters measurement technique was standardised which was in line with modified Lind's measurement technique of human dentistry. A significant decrease in least square count means of dental parameters was observed in age group 1 (0 - 12 months) in comparison with group 2 (13 - 60 months) and group 3 (> 60 months). A significant decrease in least square count means of dental parameters was observed in group A (0.00 - 10.00 kg) in comparison with group B (11.00 - 25.00 kg) and group C (> 25.00 kg). The root canal width showed a significant decrease with an increase in age; therefore, it was difficult to approach pulp cavity in older dogs. Small breeds showed decline in root length/crown height (R/C) ratio and mandible height/first mandibular molar height (MH/M1H) ratio in comparison with medium and large breeds because of which there were more chances of tooth loosening in smaller breeds. Regression equations formulated with respect to body weight and age can act as a ready reference to calculate values of different dental parameters at places where dental radiography is not available.

Interaction between sugar transport and plant development

Endogenous programs and constant interaction with the environment regulate the development of the plant organism and its individual organs. Sugars are necessary building blocks for plant and organ growth and at the same time act as critical integrators of the metabolic state into the developmental program. There is a growing recognition that the specific type of sugar and its subcellular or tissue distribution is sensed and translated to developmental responses. Therefore, the transport of sugars across membranes is a key process in adapting plant organ properties and overall development to the nutritional state of the plant. In this review, we discuss how plants exploit various sugar transporters to signal growth responses, for example, to control the development of sink organs such as roots or fruits. We highlight which sugar transporters are involved in root and shoot growth and branching, how intracellular sugar allocation can regulate senescence, and, for example, control fruit development. We link the important transport processes to downstream signaling cascades and elucidate the factors responsible for the integration of sugar signaling and plant hormone responses.

Nutrient carriers at the heart of plant nutrition and sensing

Plants require water and several essential nutrients for their development. The radial transport of nutrients from the soil to the root vasculature is achieved through a combination of three different pathways: apoplastic, symplastic, and transcellular. A common feature for these pathways is the requirement of carriers to transport nutrients across the plasma membrane. An efficient transport of nutrients across the root cell layers relies on a large number of carriers, each of them having their own substrate specificity, tissular and subcellular localization. Polarity is also emerging as a major feature allowing their function. Recent advances on radial transport of nutrients, especially carrier mediated nutrient transport will be discussed in this review, as well as the role of transporters as nutrient sensors.

Overexpression of OsHAD3, a Member of HAD Superfamily, Decreases Drought Tolerance of Rice

Haloacid dehalogenase-like hydrolase (HAD) superfamily have been shown to get involved in plant growth and abiotic stress response. Although the various functions and regulatory mechanism of HAD superfamily have been well demonstrated, we know little about the function of this family in conferring abiotic stress tolerance to rice. Here, we report OsHAD3, a HAD superfamily member, could affect drought tolerance of rice. Under drought stress, overexpression of OsHAD3 increases the accumulation of reactive oxygen species and malondialdehyde than wild type. OsHAD3-overexpression lines decreased but antisense-expression lines increased the roots length under drought stress and the transcription levels of many well-known stress-related genes were also changed in plants with different genotypes. Furthermore, overexpression of OsHAD3 also decreases the oxidative tolerance. Our results suggest that overexpression of OsHAD3 could decrease the drought tolerance of rice and provide a new strategy for improving drought tolerance in rice.

Tracking deuterium uptake in hydroponically grown maize roots using correlative helium ion microscopy and Raman micro-spectroscopy

BACKGROUND

Investigations into the growth and self-organization of plant roots is subject to fundamental and applied research in various areas such as botany, agriculture, and soil science. The growth activity of the plant tissue can be investigated by isotope labeling experiments with heavy water and subsequent detection of the deuterium in non-exchangeable positions incorporated into the plant biomass. Commonly used analytical methods to detect deuterium in plants are based on mass-spectrometry or neutron-scattering and they either suffer from elaborated sample preparation, destruction of the sample during analysis, or low spatial resolution. Confocal Raman micro-spectroscopy (CRM) can be considered a promising method to overcome the aforementioned challenges. The substitution of hydrogen with deuterium results in the measurable shift of the CH-related Raman bands. By employing correlative approaches with a high-resolution technique, such as helium ion microscopy (HIM), additional structural information can be added to CRM isotope maps and spatial resolution can be further increased. For that, it is necessary to develop a comprehensive workflow from sample preparation to data processing.

RESULTS

A workflow to prepare and analyze roots of hydroponically grown and deuterium labeled Zea mays by correlative HIM-CRM micro-analysis was developed. The accuracy and linearity of deuterium detection by CRM were tested and confirmed with samples of deuterated glucose. A set of root samples taken from deuterated Zea mays in a time-series experiment was used to test the entire workflow. The deuterium content in the roots measured by CRM was close to the values obtained by isotope-ratio mass spectrometry. As expected, root tips being the most actively growing root zone had incorporated the highest amount of deuterium which increased with increasing time of labeling. Furthermore, correlative HIM-CRM analysis allowed for obtaining the spatial distribution pattern of deuterium and lignin in root cross-sections. Here, more active root zones with higher deuterium incorporation showed less lignification.

CONCLUSIONS

We demonstrated that CRM in combination with deuterium labeling can be an alternative and reliable tool for the analysis of plant growth. This approach together with the developed workflow has the potential to be extended to complex systems such as plant roots grown in soil.

Foliar spray of stress protective chemicals alleviates cobalt toxicity by improving root antioxidant defense in maize (Zea mays)

Cobalt (Co2+) is a beneficial microelement for plants but toxic to metabolism in higher amounts. This study determined the influence of sublethal Co2+ level (0.5 mM) on the growth of maize (Zea mays L.) hybrids; Hycorn 11 plus (Co2+ sensitive) and P-1429 (Co2+ tolerant) and its alleviation with foliar spray of pre-optimized levels of stress protective chemicals (SPCs), i.e., salicylic acid (SA, 0.5 mM), thiourea (TU, 1.0 mM), and ascorbic acid (AsA, 0.5 mM) applied at seedling, vegetative, and late vegetative stages. Plants were harvested at early vegetative, late vegetative, and silking stages. Co2+ stress caused a decrease in shoot and root length, dry weight, leaf area, and culm diameter, reduced the activities of enzymatic antioxidants and concentrations of AsA and soluble phenolics more in root than shoot, but P-1429 was more tolerant of Co2+ than Hycorn 11 plus. SPCs spray alleviated oxidative damage by enhancing the antioxidant activity, AsA and soluble phenolics, sulfate-S and nitrate-N contents, which were significantly increased in roots than in shoots; P-1429 displayed better response than Hycorn 11 plus. Principal component analysis and correlation matrix revealed the profound roles of SPCs spray in improving Co2+ resistance in root leading to robust growth of hybrids. AsA was highly promising in reducing Co2+ toxicity while vegetative and silking stages were more sensitive. Results revealed that after translocation to root, the foliar-applied SPCs had individualistic modes of action in mitigating Co2+ toxicity on roots. In crux, the metabolism and phloem transport of the SPCs from shoot to root are plausible mechanism for Co2+ tolerance in maize hybrids.

Modulation of Polar Auxin Transport Identifies the Molecular Determinants of Source-Sink Carbon Relationships and Sink Strength in Poplar

Source-to-sink carbon (C) allocation driven by the sink strength, i.e., the ability of a sink organ to import C, plays a central role in tissue growth and biomass productivity. However, molecular drivers of sink strength have not been thoroughly characterized in trees. Auxin, as a major plant phytohormone, regulates the mobilization of photoassimilates in source tissues and elevates the translocation of carbohydrates toward sink organs, including roots. In this study, we used an 'auxin-stimulated carbon sink' approach to understand the molecular processes involved in the long-distance source-sink C allocation in poplar. Poplar cuttings were foliar sprayed with polar auxin transport modulators, including auxin enhancers (AE) (i.e., IBA and IAA) and auxin inhibitor (AI) (i.e., NPA), followed by a comprehensive analysis of leaf, stem, and root tissues using biomass evaluation, phenotyping, C isotope labeling, metabolomics, and transcriptomics approaches. Auxin modulators altered root dry weight and branching pattern, and AE increased photosynthetically fixed C allocation from leaf to root tissues. The transcriptome analysis identified highly expressed genes in root tissue under AE condition including transcripts encoding polygalacturonase and β-amylase that could increase the sink size and activity. Metabolic analyses showed a shift in overall metabolism including an altered relative abundance levels of galactinol, and an opposite trend in citrate levels in root tissue under AE and AI conditions. In conclusion, we postulate a model suggesting that the source-sink C relationships in poplar could be fueled by mobile sugar alcohols, starch metabolism-derived sugars, and TCA-cycle intermediates as key molecular drivers of sink strength.

Evaluation of root and canal morphology of mandibular premolar amongst Saudi subpopulation using the new system of classification: a CBCT study

BACKGROUND

The clinician should have complete knowledge of the normal anatomy of the root as well as complexities in the root canal configuration for a better outcome, as missed or improper handling of the canal system can lead to the failure of an entire endodontic procedure. The present study aims to assess the morphology of roots and canals in permanent mandibular premolars in the Saudi subpopulation with a new classification system.

METHODS

The present study includes 1230 mandibular premolars (645 first premolars and 585-second premolars) from 500 CBCT images of the patients, including retrospective data. iCAT scanner system (Imaging Sciences International, Hatfield, PA, USA) was used to obtain the images; scanning of 8 × 8 cm images was performed at 120 KVp and 5-7 mA with a voxel size of 0.2 mm. The new method of classification presented by Ahmed et al. 2017 was used to record and classify the root canal morphology, followed by recording the differences regarding the age and gender of the patients. Comparison of canal morphology in lower permanent premolars and its association with gender and age of the patients was done by Chi-square test/ Fisher exact test; the significance level was set at 5% (p ≤ 0.05).

RESULTS

The left mandibular 1st and 2nd premolars with one root were 47.31%, with two roots were 2.19%. However, three roots (0.24%) and C-shaped canals (0.24%) were reported only in the left mandibular 2nd premolar. The right mandibular 1st and 2nd premolars with one root were 47.56%, with two roots were 2.03%. The overall percentage of the number of roots and canals in the first and second premolars ¹ PM ¹ (88.38%), ² PM ¹ B ¹ L ¹ (3.5%), ² PM B ¹ L ¹ (0.65%), ¹ PM ^1-2-1 (3.08%), ¹ PM ^1-2 (3.17%), ¹ PM ^1-2-1-2 (0.24%), ³ PMMB ¹ DB ¹ L¹ (0.48%). However, the C-shaped canals (0.40%) were reported in right and left mandibular second premolars. No statistically significant difference was reported between mandibular premolars and gender. A statistically significant difference was reported between mandibular premolars and the age of the study subjects.

CONCLUSION

Type I (¹ TN ¹) was the major root canal configuration in permanent mandibular premolars, which was higher among males. The CBCT imaging provides thorough details about the root canal morphology of lower premolars. These findings could support diagnosis, decision-making, and root canal treatment, for dental professionals.

Alkaloid variations within the genus Stephania (Menispermaceae) in China

The genus Stephania, which is rich in alkaloids, has been used as a traditional medicine or folklore herb against numerous ailments in China. However, the understanding of the variation within the genus Stephania is obscure, which limits the optimal utilization of the genus. An evaluation of the variation within the genus Stephania would help screen the ideal Stephania genotypes for drug utilization. In the present study, alkaloids in the tubers of four commonly cultivated Stephania species in China, i.e., the genotype Stephania kwangsiensis Lo. (SK-guangxi) from Guangxi Province and three Stephania yunnanensis H.S. Lo. genotypes (SY-xueteng, SY-hongteng, and SY-lvteng) sourced from Yunnan Province, were investigated, and the genus variations were compared. The results revealed significant variations in the abundance of alkaloids in tubers within the genus Stephania. The Stephania genotypes SY-xueteng and SY-hongteng showed a relatively high abundance of total alkaloids compared with the Stephania genotypes SK-guangxi and SY-lvteng. Specifically, the Stephania genotype SY-xueteng had a relatively high abundance of palmatine in tubers, and the Stephania genotype SY-hongteng exhibited a high abundance of stephanine in tubers. Our study provides foundations for further utilization of ideal Stephania genotypes by clarifying the variations in the alkaloid contents within the genus in China.

Comparative study of stress characteristics around the adjacent teeth tissues during insertion of mini-screws with different insertion angles: A three-dimensional finite element study

With a limited alveolar bone position, there is a high risk that mini-screws (MS) implants could cause damage to the adjacent teeth. To reduce this damage, the position and tilt angle of the MS must be optimized. The aim of this study was to assess the effect of MS implantation angle on the stress exerted on adjacent periodontal membrane and roots. A three-dimensional finite element model containing dentition, periodontal ligament, jaw and MS were established based on the CBCT images and MS scanning data. The MS was first inserted perpendicular to the surface of the bone at specific locations and then tilted at an angle of 10° and 20° to the mesial and distal teeth, respectively. The stress distribution in the periodontal tissue of the adjacent teeth was analyzed after MS implantation at different angles.The stress on the adjacent tooth root and periodontal ligament was most uniformly distributed when the MS was inserted vertically. It changed 9.4-97.7% when the axis of MS was tilted at 10-degree and 20-degree angles from the point of vertical insertion. The stresses experienced by the periodontal ligament and the root are similar. When the horizontal angle of the MS insertion was changed, the MS was closer to the adjacent tooth, resulting in greater stress near the PDL and root. It was recommended to insert the MS vertically into the alveolar bone surface to avoid root damage due to excessive stress.

Novel whole-mount FISH analysis for intact root of Arabidopsis thaliana with spatial reference to 3D visualization

Whole-mount fluorescent in situ hybridization (WM-FISH) is an effective tool to observe chromosome behavior in tissues or organs. However, it is difficult to obtain a precise spatial profile of fluorescent signals in roots using conventional WM-FISH mainly because of the severe damage caused during the processing. To address this problem, we established a novel WM-FISH analysis for intact roots of Arabidopsis thaliana and successfully obtained a precise spatial profile of nuclear size and centromere signals. The two main improvements in the novel WM-FISH analysis are: (i) hybridization was performed directly on MAS-coated glass slides covered with silicon wells and (ii) conditions for enzyme treatment were optimized (37 °C, 45 s). After the WM-FISH using a centromere probe, we analyzed the results by 3D data processing to quantify the nuclear volume and number of centromere signals of the obtained cortical cell files and determined the position of each nucleus in intact roots. Then we plotted the nuclear volume and number of centromere signals versus distance from the quiescent center to evaluate the precise spatial profile of each parameter.

Genome-wide analysis of Panax MADS-box genes reveals role of PgMADS41 and PgMADS44 in modulation of root development and ginsenoside synthesis

Panax root is an important material used in food and medicine. Its cultivation and production usually depend on root shape and ginsenoside content. There is limited understanding about the synergistic regulatory mechanisms underlying root development and ginsenoside accumulation in Panax. MADS-box transcription factors possibly play a significant role in regulation of root growth and secondary metabolites. In this study, we identified MADS-box transcription factors of Panax, and found high expression levels of SVP, ANR1 and SOC1-like clade genes in its roots. We confirmed that two SOC1-like genes, PgMADS41 and PgMADS44, bind to expansion gene promoters (PgEXLB5 and PgEXPA13), which contribute to root growth, and to SE-4, CYP716A52v2-4, and β-AS-13 promoters, which participate in ginsenoside Ro biosynthesis. These two genes were found to increase lateral root number and main root length in transgenic Arabidopsis thaliana by improving AtEXLA1, AtEXLA3, AtEXPA5, and AtEXPA6 gene expression. As a non-phytohormone regulatory tool, Ro can stimulate adventitious root growth by influencing their expression and ginsenoside accumulation. Our study provides new insights into the coordinated regulatory function of SOC1-like clade genes in Panax root development and triterpenoid accumulation, paving the way towards understanding root formation and genetic improvement in Panax.

Liquiritigenin, isoliquiritigenin rich extract of glycyrrhiza glabra roots attenuates inflammation in macrophages and collagen-induced arthritis in rats

Liquiritigenin (LTG) and its bioprecursor isoliquiritigenin(ISL), the main bioactives from roots of Glycyrrhiza genus are progressively documented as a potential pharmacological agent for the management of chronic diseases. The aim of this study was to evaluate the pharmacological potential of liquiritigenin, isoliquiritigenin rich extract of Glycyrrhiza glabra roots (IVT-21) against the production of pro-inflammatory cytokines from activated macrophages as well as further validated the efficacy in collagen-induced arthritis model in rats. We also performed the safety profile of IVT-21 using standard in-vitro and in-vivo assays. Results of this study revealed that the treatment of IVT-21 and its major bioactives (LTG, ISL) was able to reduce the production of pro-inflammatory cytokines (TNF-α, IL-6) in LPS-activated primary peritoneal macrophages in a dose-dependent manner compared with vehicle-alone treated cells without any cytotoxic effect on macrophages. In-vivo efficacy profile against collagen-induced arthritis in Rats revealed that oral administration of IVT-21 significantly reduced the arthritis index, arthritis score, inflammatory mediators level in serum. IVT-21 oral treatment is also able to reduce the NFкB-p65 expression as evidence of immunohistochemistry in knee joint tissue and mRNA level of pro-inflammatory cytokines in paw tissue in a dose-dependent manner when compared with vehicle treated rats. Acute oral toxicity profile of IVT-21 demonstrated that it is safe up to 2000 mg/kg body weight in experimental mice. This result suggests the suitability of IVT-21 for further study in the management of arthritis and related complications.

Comparative transcriptome and genome analysis unravels the response of Tatary buckwheat root to nitrogen deficiency

Tartary buckwheat (Fagopyrum tataricum Garetn.), a dicotyledonous herbaceous crop, has good adaptation to low nitrogen (LN) condition. The plasticity of roots drives the adaption of Tartary buckwheat under LN, but the detailed mechanism behind the response of TB roots to LN remains unclear. In this study, the molecular mechanism of two Tartary buckwheat genotypes' roots with contrasting sensitivity in response to LN was investigated by integrating physiological, transcriptome and whole-genome re-sequencing analysis. LN improved primary and lateral root growth of LN-sensitive genotype, whereas the roots of LN-insensitive genotype showed no response to LN. 2, 661 LN-responsive differentially expressed genes (DEGs) were identified by transcriptome analysis. Of these genes, 17 N transport and assimilation-related and 29 hormone biosynthesis and signaling genes showed response to LN, and they may play important role in Tartary buckwheat root development under LN. The flavonoid biosynthetic genes' expression was improved by LN, and their transcriptional regulations mediated by MYB and bHLH were analyzed. 78 transcription factors, 124 small secreted peptides and 38 receptor-like protein kinases encoding genes involved in LN response. 438 genes were differentially expressed between LN-sensitive and LN-insensitive genotypes by comparing their transcriptome, including 176 LN-responsive DEGs. Furthermore, nine key LN-responsive genes with sequence variation were identified, including FtNRT2.4, FtNPF2.6 and FtMYB1R1. This paper provided useful information on the response and adaptation of Tartary buckwheat root to LN, and the candidate genes for breeding Tartary buckwheat with high N use efficiency were identified.

Variable level of genetic dominance controls important agronomic traits in rice populations under water deficit condition

Plant hybridization is an important breeding technique essential for producing a genotype (hybrid) with favorable traits (e.g., stress tolerance, pest resistance, high yield potential etc.) to increase agronomic, economic and commercial values. Studying of genetic dominance among the population helps to determine gene action, heritability and candidate gene selection for plant breeding program. Therefore, this investigation was aimed to evaluate gene action, heritability, genetic advance and heterosis of rice root, agronomic, and yield component traits under water deficit conditions. In this study, crossing was performed among the four different water-deficit tolerant rice genotypes to produce better hybrid (F₁), segregating (F₂) and back-cross (BC₁ and BC₂) populations. The Giza 178, WAB56-204, and Sakha104 × WAB56-104 populations showed the better physiological and agronomical performances, which provided better adaptability of the populations to water deficit condition. Additionally, the estimation of heterosis and heterobeltiosis of some quantitative traits in rice populations were also studied. The inheritance of all studied traits was influenced by additive gene actions. Dominance gene actions played a major role in controlling the genetic variance among studied traits in both crossed populations under well-watered and drought conditions. The additive × additive type of gene interactions was essential for the inheritance of root length, root/shoot ratio, 1,000-grain weight, and sterility % of two crossed populations under both conditions. On the contrary, the additive × dominance type of gene interactions was effective in the inheritance of all studied traits, except duration in Giza178 × Sakha106, and plant height in Sakha104 × WAB56-104 under water deficit condition. In both crosses, the dominance × dominance type of gene interactions was effective in the inheritance of root volume, root/shoot ratio, number of panicles/plant and 1,000-grain weight under both conditions. Moreover, dominance × dominance type of gene interaction played a major role in the inheritance of root length, number of roots/plant, plant height, panicle length, number of filled grain/panicle and grain yield/plant in Giza178 × Sakha106 under both conditions. The studied traits in both crossed populations indicated better genetic advance as they showed advanced qualitative and quantitative characters in rice populations under water deficit condition. Overall, our findings open a new avenue of future phenotypic and genotypic association studies in rice. These insights might be useful to the plant breeders and farmers for developing water deficit tolerant rice cultivars.

Lipid peroxide-derived short-chain aldehydes promote programmed cell death in wheat roots under aluminum stress

Lipid peroxidation is a primary event in plant roots exposed to aluminum (Al) toxicity, which leads to the formation of reactive aldehydes. Current evidence demonstrates that the resultant aldehydes are integrated components of cellular damage in plants. Here, we investigated the roles of aldehydes in mediating Al-induced damage, particularly cell death, using two wheat genotypes with different Al resistances. Aluminum treatment significantly induced cell death, which was accompanied by decreased root activity and cell length. Al-induced cell death displayed granular nuclei and internucleosomal fragmentation of nuclear DNA, suggesting these cells underwent programmed cell death (PCD). During this process, caspase-3-like protease activity was extensively enhanced and showed a significant difference between these two wheat genotypes. Further experiments showed that Al-induced cell death was positively correlated with aldehydes levels. Al-induced representative diagnostic markers for PCD, such as TUNEL-positive nuclei and DNA fragmentation, were further enhanced by the aldehyde donor (E)-2-hexenal, but significantly suppressed by the aldehyde scavenger carnosine. As the crucial executioner of Al-induced PCD, the activity of caspase-3-like protease was further enhanced by (E)-2-hexenal but inhibited by carnosine in wheat roots. These results suggest that reactive aldehydes sourced from lipid peroxidation mediate Al-initiated PCD probably through activating caspase-3-like protease in wheat roots.

The rapid-tome, a 3D-printed microtome, and an updated hand-sectioning method for high-quality plant sectioning

BACKGROUND

Microscopic analysis of plant anatomy is a common procedure in biology to study structure and function that requires high-quality sections for accurate measurements. Hand sectioning of specimens is typically limited to moderately soft tissue while harder samples prohibit sectioning by hand and/or result in inconsistent thicknesses.

RESULTS

Here we present both a clearly described hand-sectioning method and a novel microtome design that together provide the means to section a variety of plant sample types. The described hand-sectioning method for herbaceous stems works well for softer subjects but is less suitable for samples with secondary growth (e.g., wood production). Instead, the "Rapid-Tome" is a novel tool for sectioning both soft and tougher high-aspect-ratio samples, such as stems and roots, with excellent sample control. The Rapid-Tome can be 3D-printed in approximately 18 h on a mid-quality printer common at university maker spaces. After printing and trimming, Rapid-Tome assembly takes a few minutes with five metal parts common at hardware stores. Users sectioned a variety of plant samples including the hollow internodes of switchgrass (Panicum virgatum), fibrous switchgrass roots containing aerenchyma, and woody branches of eastern red cedar (Juniperus virginiana) and American sycamore (Platanus occidentalis). A comparative analyses with Rapid-Tome-produced sections readily revealed a significant difference in seasonal growth of sycamore xylem vessel area in spring (49%) vs. summer (23%). Additionally, high school students with no prior experience produced sections with the Rapid-Tome adequate for comparative analyses of various plant samples in less than an hour.

CONCLUSIONS

The described hand-sectioning method is suitable for softer tissues, including hollow-stemmed grasses and similar samples. In addition, the Rapid-Tome provides capacity to safely produce high-quality sections of tougher plant materials at a fraction of the cost of traditional microtomes combined with excellent sample control. The Rapid-Tome features rapid sectioning, sample advancement, blade changes, and sample changes; it is highly portable and can be used easily with minimal training making production of thin sections accessible for classroom and outreach use, in addition to research.

Tomato (Solanum lycopersicum) WRKY23 enhances salt and osmotic stress tolerance by modulating the ethylene and auxin pathways in transgenic Arabidopsis

Osmotic stress is one of the biggest problems in agriculture, which adversely affects crop productivity. Plants adopt several strategies to overcome osmotic stresses that include transcriptional reprogramming and activation of stress responses mediated by different transcription factors and phytohormones. We have identified a WRKY transcription factor from tomato, SlWRKY23, which is induced by mannitol and NaCl treatment. Over-expression of SlWRKY23 in transgenic Arabidopsis enhances osmotic stress tolerance to mannitol and NaCl and affects root growth and lateral root number. Transgenic Arabidopsis over-expressing SlWRKY23 showed reduced electrolyte leakage and higher relative water content than Col-0 plants upon mannitol and NaCl treatment. These lines also showed better membrane integrity with lower MDA content and higher proline content than Col-0. Responses to mannitol were governed by auxin as treatment with TIBA (auxin transport inhibitor) negatively affected the osmotic tolerance in transgenic lines by inhibiting lateral root growth. Similarly, responses to NaCl were controlled by ethylene as treatment with AgNO₃ (ethylene perception inhibitor) inhibited the stress response to NaCl by suppressing primary and lateral root growth. The study shows that SlWRKY23, a osmotic stress inducible gene in tomato, imparts tolerance to mannitol and NaCl stress through interaction of the auxin and ethylene pathways.

Morphological Complexity in Arabic Spelling and Its Implication for Cognitive Processing

Spelling poses a challenge to Arabic-speaking learners due to the complexity of the morphological and orthographic systems in Arabic. Arabic morphology has been argued to play a critical role in spelling since its morphological operations are built on a system consisting of a root that is interlocking into different patterns of vowels to form different categories of words. This study made a detailed classification of spelling errors in a word dictation task, based on morphological structures, undertaken by 107 Typically-developing learners (TD) and learners with learning disabilities (LD) attending the same schools in Jordan. All participants ranged in age from 7 years, 3 months to 15 years, 2 months (grades 2 to 8). The spelling task was made up of 400 common words representing most morphological forms in different conjugations and grammatical classes. The results indicated that TD and LD learners follow a similar pattern of complexity even though the LD group produced more errors than the TD group. Both groups encountered more difficulties in passive voice forms followed by active voice forms. Furthermore, both groups spelled nouns, verbal nouns and derivations more accurately than verbal forms (active and passive voice). The results provide additional evidence for the nonlinear growth of morphological knowledge in spelling. In addition, spelling errors suggested that the spelling process goes in a hierarchical way where words can be accessed and processed either according to the root or according to the stem. Therefore, roots or stems are firstly accessed and attached to basic word patterns (the grapheme without diacritics and affixes). Thereafter, prefixes and, then, suffixes are attached to the word pattern and, finally, diacritics are accessed and attached to the word pattern.

The Impact of Tobamovirus Infection on Root Development Involves Induction of Auxin Response Factor 10a in Tomato

Plant viruses cause systemic diseases that severely impair plant growth and development. While the accumulation of viruses in the root system has long been established, little is known as to how viruses affect root architecture. Here, we examined how the emerging tobamovirus, tomato brown rugose fruit virus (ToBRFV), alters root development in tomato. We found that ToBRFV and tobacco mosaic virus both invaded root systems during the first week of infection. ToBRFV infection of tomato plants resulted in a significant decrease in root biomass and elongation and root-to-shoot ratio and a marked suppression of root branching. Mutation in RNA-dependent RNA polymerase 6 increased the susceptibility of tomato plants to ToBRFV, resulting in severe reduction of various root growth parameters including root branching. Viral root symptoms were associated with the accumulation of auxin response factor 10a (SlARF10a) transcript, a homolog of Arabidopsis ARF10, a known suppressor of lateral root development. Interestingly, loss-of-function mutation in SlARF10a moderated the effect of ToBRFV on root branching. In contrast, downregulation of sly-miR160a, which targets SlARF10a, was associated with constitutive suppression root branching independent of viral infection. In addition, overexpression of a microRNA-insensitive mutant of SlARF10a mimicked the effect of ToBRFV on root development, suggesting a specific role for SlARF10a in ToBRFV-mediated suppression of root branching. Taken together, our results provide new insights into the impact of tobamoviruses on root development and the role of ARF10a in the suppression of root branching in tomato.

The root enrichment of bacteria is consistent across different stress-resistant plant species

Bacteria, inhabiting around and in plant roots, confer many beneficial traits to promote plant growth and health. The secretion of root exudates modulates the nutritional state of the rhizosphere and root area, further selecting specific bacteria taxa and shaping the bacteria communities. Many studies of the rhizosphere effects have demonstrated that selection by the plant rhizosphere consistently enriches a set of bacteria taxa, and this is conserved across different plant species. Root selection effects are considered to be stronger than the rhizosphere selection effects, yet studies are limited. Here, we focus on the root selection effects across a group of 11 stress-resistant plant species. We found that the root selection consistently reduced the alpha diversity (represented by total number of observed species, Shannon's diversity, and phylogenetic diversity) and altered the structure and composition of bacteria communities. Furthermore, root selection tended to enrich for clusters of bacteria genera including Pantoea, Akkermansia, Blautia, Acinetobacter, Burkholderia-Paraburkholderia, Novosphingobium, Massilia, Pseudomonas, Chryseobacterium, and Stenotrophomonas. Our study offers some basic knowledge for understanding the microbial ecology of the plant root, and suggests that several bacteria genera are of interest for future studies.

Responses of roots and rhizosphere of female papaya to the exogenous application of GA3

Exogenous GAs have an indeterminate effect on root development. Our current study used female papaya to reveal how the roots and rhizosphere respond to the exogenous application of GA₃ by investigating the transcriptome profile in roots, metabolic profile and microbial community in both roots and rhizosphere of GA₃-treated and control female papaya. The results demonstrated that exogenous GA₃ treatment enhanced female papaya lateral root development, which gave plants physical advantages of water and nutrient uptake. In addition, it was likely that GA₃ spraying in papaya shoot apices increased the level of auxin, which was transported to roots by CpPIN1, where auxin upregulated CpLBD16 and repressed CpBP to promote the lateral root initiation and development. In papaya roots, corresponding transporters (CpTMT3, CpNRT1:2, CpPHT1;4, CpINT2, CpCOPT2, CpABCB11, CpNIP4;1) were upregulated and excretion transporters were downregulated such as CpNAXT1 for water and nutrients uptake with exogenous GA₃ application. Moreover, in GA₃-treated papaya roots, CpALS3 and CpMYB62 were downregulated, indicating a stronger abiotic resistance to aluminum toxic and phosphate starvation. On the other hand, BRs and JAs, which involve in defense responses, were enriched in the roots and rhizosphere of GA₃-treated papayas. The upregulation of the two hormones might result in the reduction of pathogens in roots and rhizosphere such as Colletotrichum and Verticillium. GA₃-treated female papaya increased the abundance of beneficial bacteria species including Mycobacterium, Mitsuaria, and Actinophytocola, but decreased that of the genera Candidatus and Bryobacter for that it required less nitrate. Overall, the roots and rhizosphere of female papaya positively respond to exogenous application of GA₃ to promote development and stress tolerance. Treatment of female papaya with GA3 might result in the promotion of lateral root formation and development by upregulating CpLBD16 and downregulating CpBP. GA₃-treated papaya roots exhibited feedback control of brassinolide and jasmonate signaling in root development and defense. These findings revealed complex response to a growth hormone treatment in papaya roots and rhizosphere and will lead to investigations on the impact of other plant hormones on belowground development in papaya.