Root Material Research Articles

Gross mineralization and nitrification in degraded alpine grassland soil

Global climate changes and anthropogenic activities degrade them ecosystems, which strongly changes net nitrogen (N) mineralization in alpine grasslands, and, thus, makes them even more limited by available N. Our objective was to examine the soil gross N mineralization and nitrification depending on degradation stages in them on the example of the Tibetan Plateau. We used the in situ15N isotope dilution to quantify the gross N mineralization and nitrification of soil in three degradation stages: i) 0–5 and 5–10 cm depth of soil covered by Kobresia pygmaea community (non degraded), ii) 0–5 cm depth of soil occupied by lichens on the surface (moderately degraded), and iii) 0–5 cm in bared subsoil patches (completely degraded). The gross N mineralization rate decreased 6 times in the bared subsoil patches compared to the 5–10 cm in soil covered by Kobresia pygmaea. The gross nitrification rate of 0–5 cm depth of soil under Kobresia pygmaea community was 1.67 times higher than in the bare subsoil patches. The net N mineralization and nitrification rates were negative, pointing to strong N limitations, especially in bare subsoil patches. Among the three patch types, the bared subsoil had the slowest N transformation rates for all studied processes. As alpine grasslands degrade, net N mineralization and nitrification processes significantly decline, intensifying N limitations for plants. Furthermore, the appearance of bared subsoil patches further accelerates root mat destruction, adding complexity to ecosystem degradation and increasing N loss from the ecosystem.

Transcriptional control of hydrogen peroxide homeostasis regulates ground tissue patterning in the Arabidopsis root.

In multicellular organisms, including higher plants, asymmetric cell divisions (ACDs) play a crucial role in generating distinct cell types. The Arabidopsis root ground tissue initially has two layers: endodermis (inside) and cortex (outside). In the mature root, the endodermis undergoes additional ACDs to produce the endodermis itself and the middle cortex (MC), located between the endodermis and the pre-existing cortex. In the Arabidopsis root, gibberellic acid (GA) deficiency and hydrogen peroxide (H2O2) precociously induced more frequent ACDs in the endodermis for MC formation. Thus, these findings suggest that GA and H2O2 play roles in regulating the timing and extent of MC formation. However, details of the molecular interaction between GA signaling and H2O2 homeostasis remain elusive. In this study, we identified the PEROXIDASE 34 (PRX34) gene, which encodes a class III peroxidase, as a molecular link to elucidate the interconnected regulatory network involved in H2O2- and GA-mediated MC formation. Under normal conditions, prx34 showed a reduced frequency of MC formation, whereas the occurrence of MC in prx34 was restored to nearly WT levels in the presence of H2O2. Our results suggest that PRX34 plays a role in H2O2-mediated MC production. Furthermore, we provide evidence that SCARECROW-LIKE 3 (SCL3) regulates H2O2 homeostasis by controlling transcription of PRX34 during root ground tissue maturation. Taken together, our findings provide new insights into how H2O2 homeostasis is achieved by SCL3 to ensure correct radial tissue patterning in the Arabidopsis root.

Efficiency of Strawberry Cultivation under the Effect of Different Types of Plants in a Soilless System in the High-Altitude Regions of Southern Brazil

By analyzing the growth and development of different types of strawberry plants, the researchers were able to evaluate the interference with the horticultural potential of the cultivar ‘Albion’. The five treatments that have been studied corresponded to different types of strawberry plants: mini plants in trays with young roots, plants in trays with mature roots and an initial reduction of fertigation, plants in trays with mature roots, plants with bare roots, and plants in trays with mature roots preserved by the cold. In bags containing coconut fiber, the experiment was laid out in a randomized block design with three replications. The attributes evaluated were the total yield per plant, the total yield per plant with fruits above 10 g, the total yield per hectare, the total yield per hectare with fruits above 10 g, the average plant diameter, the average number of buds per plant, and the average number of stolons per plant. There were no significant effects among the plant types concerning yield production. Plants in cold-preserved trays with mature roots showed a higher number of buds than plants in trays with mature roots. Cold-preserved tray plants with mature roots produced the highest number of stolons, followed by bare-root plants. It is concluded that the types of strawberry seedlings did not influence the productive performance of the strawberry ‘Albion’ cultivar. However, cold-preserved tray plants with mature roots showed better vegetative performance, with a yield of a higher number of buds and stolons. However, the results were influenced by the agroclimatic conditions of the producing region; due to climatic interference in the behaviour of the plants about the factors studied, it is recommended to repeat the experiment for a better understanding of the objectives.

The ERF transcription factor LTF1 activates DIR1 to control stereoselective synthesis of antiviral lignans and stress defense in Isatis indigotica roots

Lignans are a powerful weapon for plants to resist stresses and have diverse bioactive functions to protect human health. Elucidating the mechanisms of stereoselective biosynthesis and response to stresses of lignans is important for the guidance of plant improvement. Here, we identified the complete pathway to stereoselectively synthesize antiviral (−)-lariciresinol glucosides in Isatis indigotica roots, which consists of three-step sequential stereoselective enzymes DIR1/2, PLR, and UGT71B2. DIR1 was further identified as the key gene in respoJanuary 2024nse to stresses and was able to trigger stress defenses by mediating the elevation in lignan content. Mechanistically, the phytohormone-responsive ERF transcription factor LTF1 colocalized with DIR1 in the cell periphery of the vascular regions in mature roots and helped resist biotic and abiotic stresses by directly regulating the expression of DIR1. These systematic results suggest that DIR1 as the first common step of the lignan pathway cooperates with PLR and UGT71B2 to stereoselectively synthesize (−)-lariciresinol derived antiviral lignans in I. indigotica roots and is also a part of the LTF1-mediated regulatory network to resist stresses. In conclusion, the LTF1-DIR1 module is an ideal engineering target to improve plant Defenses while increasing the content of valuable lignans in plants.

Experimental Study of Arc Erosion in Gas-blasting and Free-burning Conditions in High-voltage Circuit Breakers

Arc erosion behavior depends on varieties of factors, such as the shape and material of contacts, the gas type and the pressure filled in the chamber. In this contribution, experimental research on the gas-blasting and free-burning conditions was carried out in a model circuit breaker to investigate the gas blowing effect on the mass loss of arcing contacts. SF6 was filled in the chamber and copper-tungsten was used as the contact material. Three different peak current amplitudes (5/20/35kA) were selected, and the average mass loss of plug contact was measured after five consecutive arcing tests. The erosion physical process between arc root and contact material is extremely complex. The mass loss was estimated with four different indexes, which include integral of current squared, thermal stress, transferred electric charge and arc energy. It has been found that the arc energy can be used to represent the degree of arc erosion to relate the gas-blasting and free-burning conditions.

Putative Daucus carota Capsanthin-Capsorubin Synthase (DcCCS) Possesses Lycopene β-Cyclase Activity, Boosts Carotenoid Levels, and Increases Salt Tolerance in Heterologous Plants.

Plant carotenoids are synthesized and accumulated in plastids through a highly regulated pathway. Lycopene β-cyclase (LCYB) is a key enzyme involved directly in the synthesis of α-carotene and β-carotene through the cyclization of trans-lycopene. Daucus carota harbors two LCYB genes, of which DcLCYB2 (annotated as CCS-Like) is mostly expressed in mature storage roots, an organ that accumulates high α-carotene and β-carotene content. In this work, we determined that DcLCYB2 of the orange Nantes variety presents plastid localization and encodes for a functional LCYB enzyme determined by means of heterologous complementation in Escherichia coli. Also, ectopic expression of DcLCYB2 in tobacco (Nicotiana tabacum) and kiwi (Actinidia deliciosa) plants increases total carotenoid content showing its functional role in plants. In addition, transgenic tobacco T2 homozygous plants showed better performance under chronic salt treatment, while kiwi transgenic calli also presented a higher survival rate under salt treatments than control calli. Our results allow us to propose DcLCYB2 as a prime candidate to engineer carotenoid biofortified crops as well as crops resilient to saline environments.

Cytokinin application improving growth, sugar content, polyphenol and flavonoid content in Yacon tuberous roots

Yacon is a tuberous crop that accumulates sugar in large quantities and has many valuable secondary compounds in medicine such as phenolic compounds and flavonoids. The objective of this study was to increase the size and content of sugars, polyphenols and flavonoids during the early growth of tubers. Therefore, early tuber stimulation and tuber size are important as they determine yield over time. Cell restructuring along with growth expansion as well as control of tuber reserves also takes place. This study investigated anatomy structure changes, fresh weight, dry weight, respiratory intensity and sugar content in different Yacon root types. A spray of N-benzyl adenine (BA) (0–25 ppm) is applied in the initial stage. Determining agronomic, physiological, and, biochemical indicators after 4 weeks of treatment, the sugar content of tubers determines the yield of tubers after 16 weeks of treatment. The results showed that Yacon crops at the stages of 5 to 9 weeks develop fibrous roots, thin fibrous roots and pre-tuberous roots at week 13, intermediate storage roots at week 17 and mature storage roots at week 17. BA 20 ppm application on Yacon crop week 13 increased the number of storage roots, fresh weight, dry weight tuber diameter, total sugar content, fructan content, total phenolic and flavonoid remarkably compared to controls, but reducing sugar content is lower than treating BA at 15 ppm. BA 20 ppm application on Yacon crop week 13 increased the parameters of sugar growth and accumulation, tuber yeild on a plant increased 2 times, dry weight increased 1.65 times, sugar content, total sugar 1.12 times, reducing sugar 3.01 times, fructan 1.36 times, total phenolic and flavonoid 1.36 and 1.26 times after 25 weeks of treatment.

Impact of Contracted Endodontic Access Cavities on the Fracture Resistance of Endodontically Treated Teeth After Mechanical Aging by Simulated Chewing Forces

IntroductionThis in vitro study aimed to comparatively evaluate the fracture resistance of contracted endodontic cavities (CECs) versus traditional endodontic cavities (TECs) in mandibular molars after subjecting the samples to a chewing simulator. MethodsA total of 24 freshly extracted human mandibular molars were included in the study. Teeth with intact crowns and mature root apices that were devoid of caries, attrition, restorations, and cracks were selected and randomly assigned to 3 groups (n = 8) as follows: Group 1: TECs, Group 2: CECs, and Group 3: intact teeth (control group). After endodontic treatment, the teeth were restored with EverX bulk-fill composite and layered occlusally with nanohybrid composite SolareX and subjected to a chewing simulator where 240,000 masticatory cycles were simulated, which translates to 1 year of clinical function. The teeth were then subjected to static loading in a universal testing machine and the maximum load to fracture and the pattern of failure (restorable/unrestorable) were recorded. Data were evaluated with analysis of variance and the Tukey post hoc test for multiple comparisons. ResultsThe CEC group had higher fracture resistance when compared with the TEC group; however, the difference was not statistically significant. The fracture resistance of the samples in the control group was statistically higher than those in the experimental groups (P < .005). ConclusionsThere was no difference observed in the fracture resistance of mandibular molars with TECs and CECs subjected to masticatory loading.

Effects of editing DFR genes on flowers, leaves, and roots of tobacco

BackgroundDFR is a crucial structural gene in plant flavonoid and polyphenol metabolism, and DFR knockout (DFR-KO) plants may have increased biomass accumulation. It is uncertain whether DFR-KO has comparable effects in tobacco and what the molecular mechanism is. We employed the CRISPR/Cas9 method to generate a knockout homozygous construct and collected samples from various developmental phases for transcriptome and metabolome detection and analysis.ResultsDFR-KO turned tobacco blossoms white on homozygous tobacco (Nicotiana tabacum) plants with both NtDFR1 and NtDFR2 knockout. RNA-seq investigation of anthesis leaf (LF), anthesis flower (FF), mature leaf (LM), and mature root (RM) variations in wild-type (CK) and DFR-KO lines revealed 2898, 276, 311, and 101 differentially expressed genes (DEGs), respectively. DFR-KO primarily affected leaves during anthesis. According to KEGG and GSEA studies, DFR-KO lines upregulated photosynthetic pathway carbon fixation and downregulated photosystem I and II genes. DFR-KO may diminish tobacco anthesis leaf photosynthetic light reaction but boost dark reaction carbon fixation. DFR-KO lowered the expression of pathway-related genes in LF, such as oxidative phosphorylation and proteasome, while boosting those in the plant–pathogen interaction and MAPK signaling pathways, indicating that it may increase biological stress resistance. DFR-KO greatly boosted the expression of other structural genes involved in phenylpropanoid production in FF, which may account for metabolite accumulation. The metabolome showed that LF overexpressed 8 flavonoid metabolites and FF downregulated 24 flavone metabolites. In DFR-KO LF, proteasome-related genes downregulated 16 amino acid metabolites and reduced free amino acids. Furthermore, the DEG analysis on LM revealed that the impact of DFR-KO on tobacco growth may progressively diminish with time.ConclusionThe broad impact of DFR-KO on different phases and organs of tobacco development was thoroughly and methodically investigated in this research. DFR-KO decreased catabolism and photosynthetic light reactions in leaves during the flowering stage while increasing carbon fixation and disease resistance pathways. However, the impact of DFR-KO on tobacco growth steadily declined as it grew and matured, and transcriptional and metabolic modifications were consistent. This work offers a fresh insight and theoretical foundation for tobacco breeding and the development of gene-edited strains.

Overexpression of LaGRAS enhances phosphorus acquisition via increased root growth of phosphorus-deficient white lupin.

The GRAS transcription factors play an indispensable role in plant growth and responses to environmental stresses. The GRAS gene family has extensively been explored in various plant species; however, the comprehensive investigation of GRAS genes in white lupin remains insufficient. In this study, bioinformatics analysis of white lupin genome revealed 51 LaGRAS genes distributed into ten distinct phylogenetic clades. Gene structure analyses revealed that LaGRAS proteins were considerably conserved among the same subfamilies. Notably, twenty-five segmental duplications and a single tandem duplication showed that segmental duplication was the major driving force for the expansion of GRAS genes in white lupin. Moreover, LaGRAS genes exhibited preferential expression in young cluster root and mature cluster roots and may play key roles in nutrient acquisition, particularly phosphorus (P). To validate this, RT-qPCR analysis of white lupin plants grown under +P (normal P) and -P (P deficiency) conditions elucidated significant differences in the transcript level of GRAS genes. Among them, LaGRAS38 and LaGRAS39 were identified as potential candidates with induced expression in MCR under -P. Additionally, white lupin transgenic hairy root overexpressing OE-LaGRAS38 and OE-LaGRAS39 showed increased root growth, and P concentration in root and leaf compared to those with empty vector control, suggesting their role in P acquisition. We believe this comprehensive analysis of GRAS members in white lupin is a first step in exploring their role in the regulation of root growth, tissue development, and ultimately improving P use efficiency in legume crops under natural environments. This article is protected by copyright. All rights reserved.

Stigmaria: on the substrate before in the substrate

Stigmaria is the rooting organ of late Paleozoic arborescent lycopsids. Previous scientific considerations of the stigmarian habit have placed the entire rooting organ shallow beneath the substrate surface, despite the proximal main stigmarian axes radiating outwards orthogonally from the trunk in all known stump casts with attached Stigmaria. Here, we show definitively that stigmarian axes were subaerial proximally given both their preservation within and direct interaction with two independent volcanic ash layers. However, it remains uncertain whether these axes dove under the substrate surface distally and, if so, where along the axes this occurred. We test the aboveground or belowground nature of distal stigmarian axes with comparisons of sampling frequencies of vasculature from different regions of the arborescent lycopsid body plan as preserved in ‘coal ball’ permineralization fossils from the Pennsylvanian of Euramerica. The overabundance of root versus shoot material has previously been recognized as evidence of the enhanced preservation potential of organs growing within, rather than above, the substrate. We find that specifically the terminal stigmarian axis vasculature is overrepresented in the fossil record compared to trunk and proximal stigmarian axis vasculature, suggesting that the primary stigmarian axes and their secondary branches grew on the substrate before eventually going underground distally. Implications for arborescent lycopsid establishment are considered.

A Comparative Evaluation of Efficacy of Various Obturating Techniques for the Presence of Voids.

Evaluation of the efficacy of different obturating techniques and assessment of the presence of voids in different regions of the canal. Sixty permanent single-rooted teeth with complete, mature root apices without any anatomic variation having straight patent root canals were included in the present study. Access cavity preparation followed by biomechanical preparation was done. Samples were divided into three groups-Group A: Single cone obturation, Group B: GuttaFlow 2, and Group C: GuttaCore, and obturation was carried out. The samples after obturation were stored at 370°C and 100% humidity in an incubator for 7 days to give adequate time for obturating materials to set. Cone beam computed tomography was performed with i-cat Cb 500 machine. The voids were checked on the root canal wall. The statistical analysis was done and the data after the statistical analysis was presented. GuttaCore obturators presented a lesser volume of voids followed by GuttaFlow 2 than the single cone techniques. All the obturation techniques presented an inadequacy of obturation when the pre- and post-obturated volume of the root canal space was calculated. However, no statistically significant obturated volume differences were found between single cone and GuttaFlow 2 or between GuttaFlow 2 and GuttaCore system.

Effects of Different Culture Times Genes Expression on Ginsenoside Biosynthesis of the Ginseng Adventitious Roots in Panax ginseng

Panax ginseng is an ancient and very potent herb, which has a long history of medicinal use, and recent studies have shown that ginsenosides are the main active substances in its pharmacological effects. However, the saponin content of wild ginseng and cultivated ginseng can hardly meet the market supply, and the ginseng adventitious root suspension culture technology can produce ginsenosides in a targeted manner. The length of culture time is an important factor affecting the growth and development of plants and the accumulation of secondary metabolites. After transcriptome sequencing of ginseng adventitious root material at different culture times, the results showed that a total of 5784 differentially expressed genes were screened, which contained 239 transcription factors. KEGG analysis showed that these differentially expressed genes were mainly enriched in metabolic pathways and biosynthesis of secondary metabolites. A proposed temporal analysis of differentially expressed genes among the two groups distributed the differentially expressed genes under nine clusters, and the differentially expressed genes under different clusters had the same expression trends, indicating that these genes can be jointly involved in specific biological processes. Extraction of ginsenosides from ginseng adventitious roots using water-saturated n-butanol and detection of ginsenoside content by high-performance liquid chromatography revealed a significant increase in total saponins and protopanaxadiol ginsenosides (particularly significant for ginsenosides Rd and Rb1), an increase in bioaccumulation of some protopanaxatriol ginsenosides, and a decrease in some protopanaxatriol ginsenosides (S-Rh1, R-Rg3, and Rf) saponin content decreased. We also found seven genes involved in ginsenoside biosynthesis and that the changes in these genes’ expression may be related to the accumulation of ginsenosides.

Use of extracts of Tithonia diversifolia and Gymnanthemum amygdalinum in the control of Meloidogyne incognita

Meloidogyne incognita (kofoid &amp; white) chitwood. is one of the species of phytoparasitic nematodes that causes the most losses to world agriculture. The aim of the study was to evaluate the effect of the aqueous extracts of Tithonia diversifolia and Gymnanthemum amygdalinum on the hatching of juveniles of M. incognita and their effect on tomato plants. The extracts were obtained by dynamic infusion. For the in vitro test, microtubes containing extract and the suspension of nematode eggs were prepared. After 15 days of incubation, the number of eggs and mobile and immobile juveniles were evaluated to calculate hatch inhibition. The results demonstrated that all the tested extracts had an inhibitory effect on the hatching of M. incognita when compared to the conventional nematicide. In the in vivo test, tomato plants of the cultivar Santa Cruz Kada, aged three weeks, were inoculated with a suspension with 2000 eggs of M. incognita and subjected to application of the extracts. After 60 days, the reproduction factor (FR) and the number of galls/grams of root (NGGR) were evaluated, as well as the weight of the fresh root material (PMFR) and the aerial part of the plants (PFPA). The best results were observed in plants treated with the extract of the leaves and dry stem of T. diversifolia.

Mucilage secretion by aerial roots in sorghum (Sorghum bicolor): sugar profile, genetic diversity, GWAS and transcriptomic analysis.

Aerial root mucilage can enhance nitrogen fixation by providing sugar and low oxygen environment to the rhizosphere microbiome in Sierra Mixe maize. Aerial root mucilage has long been documented in sorghum (Sorghum bicolor), but little is known about the biological significance, genotypic variation, and genetic regulation of this biological process. In the present study, we found that a large variation of mucilage secretion capacity existed in a sorghum panel consisting of 146 accessions. Mucilage secretion occurred primarily in young aerial roots under adequately humid conditions but decreased or stopped in mature long aerial roots or under dry conditions. The main components of the mucilage-soluble were glucose and fructose, as revealed by sugar profiling of cultivated and wild sorghum. The mucilage secretion capacity of landrace grain sorghum was significantly higher than that of wild sorghum. Transcriptome analysis revealed that 1844 genes were upregulated and 2617 genes were downregulated in mucilage secreting roots. Amongst these 4461 differentially expressed genes, 82 genes belonged to glycosyltransferases and glucuronidation pathways. Sobic.010G120200, encoding a UDP-glycosyltransferase, was identified by both GWAS and transcriptome analysis as a candidate gene, which may be involved in the regulation of mucilage secretion in sorghum through a negative regulatory mechanism.

Overexpression of a Grape MYB Transcription Factor Gene VhMYB2 Increases Salinity and Drought Tolerance in Arabidopsis thaliana.

In viticulture, the highly resistant rootstock 'Beta' is widely used in Chinese grape production to avoid the effects of soil salinization and drought on grape growth. However, the mechanism of high resistance to abiotic stress in the 'Beta' rootstock is not clear. In this study, we demonstrated that VhMYB2 as a transcription factor made a significant contribution to salinity and drought stress, which was isolated from the 'Beta' rootstock. The coding sequence of the VhMYB2 gene was 858 bp, encoding 285 amino acids. The subcellular localization of VhMYB2 was located in the nucleus of tobacco epidermal cells. Moreover, RT-qPCR found that VhMYB2 was predominantly expressed in the mature leaf and root of the grape. Under salinity and drought stress, overexpressing VhMYB2 showed a higher resistant phenotype and survival rates in A. thaliana while the transgenic lines had a survival advantage by measuring the contents of proline, chlorophyll, and MDA, and activities of POD, SOD, and CAT, and expression levels of related stress response genes. The results reveal that VhMYB2 may be an important transcription factor regulating 'Beta' resistance in response to abiotic stress.

Legacy effects of rhizodeposits on soil microbiomes: A perspective

Plant legacy effects observed in plant-soil feedback experiments have largely been attributed to the root or litter material of the previous plant. The legacy effects of rhizodeposits are defined as changes in the soil microbiome that remain after a plant has died or been removed from the soil and caused by the release of substances of various compositions by living plants (rhizodeposits). Rhizodeposit-mediated legacy effects have been largely ignored mainly due to the high spatial and temporal variability of rhizodeposits and difficulties quantifying and tracking them in the rhizosphere. In this perspective article, we discuss what is known about the legacy effects of rhizodeposits and provide ideas for future experiments to improve understanding of this phenomenon. Only a few studies separate rhizodeposit-mediated plant legacy effects from legacy effects of root decomposition. Results from these experiments indicate that rhizodeposit-mediated legacy effects on soil microbial communities may persist for several months to several years, especially if the same crop is cultivated persistently for several years in a ‘conditioning’ phase. Rhizodeposit-mediated legacy effects on fungal communities usually last longer than those on bacterial communities due to fungal life-cycle strategies (spore formation) and slower reproduction rates, compared to bacterial communities. We highlight the need for further experimentation to investigate the influence that the length of a conditioning phase has on the persistence of the legacy effect, differentiate the effect of root exudates from the effects of sloughed root cells, separate the influence of simple sugars from that of high molecular-weight exudates and plant derived compounds with antimicrobial properties, and explore whether plant species diversity influences the nature of the legacy. To address these questions, we propose the use of contemporary tools such as stable isotope probing, plant genetics, and reverse microdialysis. We think that harnessing rhizodeposit-mediated plant legacy effects could be a promising approach to improve sustainable crop production by creating disease-suppressive soils and simulating plant growth-promoting micro-organisms within soil systems.

BASIC DIRECTIONS IN FLUOROSIS TREATMENT

The territory of Poltava region belongs to the Buchatsky hydrogeological province, whose groundwater is characterized by an elevated fluorine level content. The cause of endemic dental fluorosis particularly in the children’s population of the region is water consumption with surplus concentration of this chemical element. Also, having fluorosis a condition that develops from a high fluoride concentration in drinking water- causes disorder of hard tooth tissues maturing, mineralizationand teeth germ development. This, in turn, has a negative influence on enamel amelogenin synthesis and violation of the crystals maturing, determines a surface porosity. The chalky spots, brown pigmentation, and enamel erosion destruction lesions are characterized the different severity manifestation of the fluorosis.&#x0D; The purpose of our research was to conduct a thorough analysis of all the material we found on this topic, gather all possible information on new trends in recent years in the treatment of dental fluorosis: what are the methods, their origins, indications for use, clinical stages and advantages.&#x0D; Dental enamel fluorosis requires different approaches to treatment depending on the severity of clinical manifestations. Obviously, as the leading method is remineralizing therapy. One of the method is offered by Nikolishina E.V. etc. [6], which is carried out in the following way: after carry out of the professional hygiene procedure, next step, individual caps were made of transparent silicone filled with 10% solution «Poltavsky Bishofit» and applied on the fluorosis teeth, daily course consist with 30 minutes and 10-20 procedures.&#x0D; Enamel microabrasion is the first minimally invasive treatment method of mild and moderate dental fluorosis using to removes opaque brown spots and surface roughness smoothing, providing a flat and shinier surface. The microabrasion technique involves etching with mild acid in combination with application of abrasive components. Resin infiltration has also become a popular treating dental fluorosis technique without loss of hard tissue.&#x0D; Resin infiltration is based on the application of hydrochloric acid to the hard tissues of the tooth and subsequent coating with a low-viscosity resin that penetrates into the microspaces of the tooth enamel. The cloaking effect is based on the refractive index. The optical properties of the affected enamel change and it looks like a healthy enamel surrounding. The indication to dental fluorosis treatment of severity forms in permanent teeth with mature roots is restoration of teeth, veneers, orthopedic crowns, if the microabrasive method hasn’t aesthetic effect efficiency.&#x0D; Thus, in cases of aesthetic changes due to fluorosis, minimally invasive restorative approaches that preserve dental hard tissue such as microabrasion method, external bleaching or resin infiltration should be considered before invasive restorative procedures. More invasive treatments may be considered if the results remain unsatisfactory.

Plant stem cells under low oxygen: metabolic rewiring by phytoglobin underlies stem cell functionality.

Root growth in maize (Zea mays L.) is regulated by the activity of the quiescent center (QC) stem cells located within the root apical meristem. Here, we show that despite being highly hypoxic under normal oxygen tension, QC stem cells are vulnerable to hypoxic stress, which causes their degradation with subsequent inhibition of root growth. Under low oxygen, QC stem cells became depleted of starch and soluble sugars and exhibited reliance on glycolytic fermentation with the impairment of the TCA cycle through the depressed activity of several enzymes, including pyruvate dehydrogenase (PDH). This finding suggests that carbohydrate delivery from the shoot might be insufficient to meet the metabolic demand of QC stem cells during stress. Some metabolic changes characteristic of the hypoxic response in mature root cells were not observed in the QC. Hypoxia-responsive genes, such as PYRUVATE DECARBOXYLASE (PDC) and ALCOHOL DEHYDROGENASE (ADH), were not activated in response to hypoxia, despite an increase in ADH activity. Increases in phosphoenolpyruvate (PEP) with little change in steady-state levels of succinate were also atypical responses to low-oxygen tensions. Overexpression of PHYTOGLOBIN 1 (ZmPgb1.1) preserved the functionality of the QC stem cells during stress. The QC stem cell preservation was underpinned by extensive metabolic rewiring centered around activation of the TCA cycle and retention of carbohydrate storage products, denoting a more efficient energy production and diminished demand for carbohydrates under conditions where nutrient transport may be limiting. Overall, this study provides an overview of metabolic responses occurring in plant stem cells during oxygen deficiency.

Root phenological and physiological response of maize (Zea mays L.) for adaptation under drought stress at vegetative and reproductive stages ​

Drought stress is known to negatively affect vegetative growth and biomass production, as well as the development of reproductive organs and yield characteristics in maize. The crop root systems are crucial for adaptability to various biotic and abiotic stresses, but studies addressing this are quite limited. The experiment was conducted simultaneously in both glasshouse and field condition during summer 2022 at TNAU, Coimbatore. The study was focussed to assess the root system architecture (RSA) of the drought tolerant and drought susceptible hybrids using PVC cylinders by imposing stress at V4 stage and root pulled out from the fieldby imposing stress at V14 stage. The results from the study showed that the significant variation was observed in both latter vegetative and mature root system under drought stress. Apart, the reduction in relative water content, SPAD values and increase of proline content were observed. The photosynthetic rate and gas exchange parameters were decreased upon exposure to drought stress. On considering, the hybrid N10-51 × DQL80 can accumulate osmolytes, maintaining tissue water potential and photosynthetic functionality for longer time when compared to other hybrids. This hybrid also exhibited the deep rooting ability with high yield under drought stress. Hence, it was identified as the drought tolerant hybrid and could be commercialized after testing their yield stability.