Polyethylene microplastics alter root functionality and affect strawberry plant physiology and fruit quality traits.

Strawberry, a globally popular crop whose fruit are known for their taste and health benefits, were used to evaluate the effects of polyethylene microplastics (PE-MPs) on plant physiology and fruit quality. Plants were grown in 2-L pots with natural soil mixed with PE-MPs at two concentrations (0.2% and 0.02%; w/w) and sizes (⌀ 35 and 125 µm). Plant physiological responses, root histochemical and anatomical analyses as well as fruit biometric and quality features were conducted. Plants subjected to ⌀ 35 µm/0.2% PE-MPs exhibited the most severe effects in terms of CO2 assimilation due to stomatal limitations, along with the highest level of oxidative stress in roots. Though no differences were observed in plant biomass, the impact on fruit quality traits was severe in ⌀ 35 µm/0.2% MPs treatment resulting in a drop in fruit weight (-42%), soluble solid (-10%) and anthocyanin contents (-25%). The smallest sized PE-MPs, adsorbed on the root surface, impaired plant water status by damaging the radical apparatus, which finally resulted in alteration of plant physiology and fruit quality. Further research is required to determine if these alterations also occur with other MPs and to understand more deeply the MPs influence on fruit physio-chemistry.

Root damage of street trees in urban environments: An overview of its hazards, causes, and prevention and control measures.

Root damage from urban street trees represents a substantial concern arising from the conflict between root growth and limited growth spaces. Nonetheless, the phenomenon of root damage, which threatens the safety of urban facilities, appears to have received little scholarly attention. Moreover, the effectiveness of some proposed measures for root damage prevention and control has not yet received consistent evaluation. Accordingly, this review aims to examine root damage, including its causes and available prevention and control measures. Urban trees are found to have a high potential to exert root damage on infrastructures when the following factors exist. These include large and mature tree, fast-growing trees, trees planted in limited soil volumes, shallow-rooted tree with buttress roots, trees whose diameter at breast height exceeds 10 cm, old and cracked road paving, high soil surface moisture content, short distances between trees and sidewalks (<2 to 3 m), and underground pipes that are already broken and made of metals or stones. The phenotypic traits of trees may be the primary factor causing root damage when there is a mismatch between the root-soil requirements of urban street trees and the actual soil environment. The poor effectiveness of root damage prevention and control measures may be attributed to the lack of connection between the development of control measures and the mechanism of root damage.

Microplastics reduce nitrogen uptake in peanut plants by damaging root cells and impairing soil nitrogen cycling.

Microplastic (MP) pollution severely impairs the sustainable development of modern agriculture. However, the mechanisms underlying the effects of MP contaminants on nutrient cycles in agroecosystems are poorly understood. In this study, we examined the impacts of two types of MPs, polypropylene (PP) and rubber crumb (RC), on nitrogen (N) transformation and N cycling in soil-peanut system. High concentrations of PP (1% w/w) and RC (1% w/w) inhibited vegetative growth and N uptake in peanut plants by damaging root cells and disturbing soil N cycling. These MPs damaged the plasma membranes of root cells and caused oxidative stress, as evidenced by the decreased number of xylem vessels, which in turn inhibited N uptake by roots. Integrated metagenomic and metabolomic analyses revealed that the differential soil metabolite levels in response to MP treatment affected the microbial community structure in the rhizosphere and the expression of key N cycling-related genes, resulting in altered N transformation and the decreased availability of N in rhizosphere soil. These findings provide the first evidence of the effects of MPs on N uptake in peanut plants and shed light on the importance of rational management of MPs for crop growth and yield in agroecosystems.

Chlorophyll a fluorescence as a tool to monitor physiological status in the leaves of Artemisia ordosica under root cutting conditions.

Background: Root cutting caused by underground coal mining subsidence is among the leading causes of plant damage in western China. Detection of root cutting stress is of great importance in evaluating the degree of plant damage and changes in physiological conditions in underground coal mining disturbance conditions. Methods: The present study assessed the use of chlorophyll fluorescence OJIP transient data to evaluate the disturbance characteristics of root cutting stress on leaf photosynthetic mechanisms in the typical shrub Artemisia ordosica Krasch. Different root cutting ratios (10%, 20%, 30%, 50%, 75%, and 100%) were established on the roots of A. ordosica in the field, and the OJIP transient and JIP parameters of the leaves were measured. Results: The overall OJIP curves and each OJIP step in leaves decreased as the root cutting ratio increased, but the impact was relatively small for root cutting ratios of less than 30%. Through the analysis of JIP parameters and the established energy pipeline model, it was found that the energy capture efficiency and electron transfer efficiency of photosystem II decreased as the root cutting ratio increased. Therefore, we also inferred that the threshold for the plant root cutting ratio at which leaf photosynthetic mechanisms begin to change is 30-50%. Conclusion: These results indicate that OJIP transient analysis can serve as a non-destructive, rapid technique for detecting plant root cutting stress in coal mining subsidence areas, which is of great value for non-destructive monitoring of plant root damage.

Risk of root damage after using lateral cephalogram and intraoral scan for guided insertion of palatal miniscrews.

BACKGROUND: Guided insertion of palatal miniscrews using a lateral cephalogram instead of cone beam computed tomography (CBCT) significantly reduces the radiation level for the patient. Till now no data are available on the risk of hitting the incisors in this regard, which is one of the worst clinical complications when inserting a paramedian miniscrew. Hence, this study aims to investigate the distance between the mini-implant and the roots of the central and lateral incisors. METHODS: Lateral cephalogram, an intraoral scan, and CBCT of 20 patients were superimposed. After a miniscrew (1.7 × 8 mm) placement based on intraoral scan and lateral cephalogram, the CBCT was used as control for the distance between the miniscrews and the roots of the incisors. RESULTS: The mean value of the shortest distance between the miniscrew and roots of the incisors in the lateral cephalogram was 4.74 ± 1.67 mm. The distance between both miniscrews and the central incisors measured in the CBCT was 5.03 ± 2.22 mm and 5.26 ± 2.21 mm and between the two miniscrews and the lateral incisors was 4.93 ± 1.91 mm and 5.21 ± 2.64 mm. No significant differences between the distances in the CBCT and the lateral cephalogram could be observed. In one case, the CBCT control revealed the penetration of two palatally displaced canines after insertion based on intraoral scan and lateral cephalogram. CONCLUSIONS: The use of an intraoral scan and a lateral cephalogram for guided paramedian insertion of palatal miniscrews can prevent incisor root damage. This may reduce the radiation since no CBCT seems necessary. The current investigation focuses on the anterior paramedian area of the palate. Outside that region and in complex cases with displaced teeth in the palatal area, a CBCT might be indicated.

Phytotoxicity of Chemical Compounds from Cinnamomum camphora Pruning Waste in Germination and Plant Cultivation.

Much previous research has indicated most composts of pruning waste are characterized by potential phytotoxicity, it is highly correlated with the chemical compounds of raw materials. Cinnamomum camphora, a common kind of pruning waste in Southeast Asia and East Asia, is characterized by intense bioactivities due to complex chemical components. This study investigated the potential phytotoxicity of C. camphora pruning waste in light of germination and higher plant growth. C. camphora extracted from leaves completely inhibited seed germination and still showed suppression of root elongation at an extremely low dosage. C. camphora extract also displayed significant inhibition of nutrient absorption in tomato seedlings, including moisture, available nutrients (N, P and K) and key microelements (Fe, Mn, Zn and S). The gene expression of aquaporins and transporters of nitrate and phosphate was significantly up-regulated in roots. This could be regarded as a positive response to C. camphora extract for enhancing nutrient absorption. Moreover, the severe damage to the plasma membrane in roots caused by C. camphora extract might seriously affect nutrient absorption. Camphor is the main component of the C. camphora extract that may induce the phytotoxicity of plasma membrane damage, resulting in the inhibition of nutrient absorption and low biomass accumulation. This study provided a new understanding of the ecotoxicological effects of C. camphora pruning waste, indicating that the harmless disposal of pruning waste requires much attention and exploration in the future.

Effect of a digital guide on the positional accuracy of intermaxillary fixation screw implantation in orthognathic surgery.

BACKGROUND: Intermaxillary fixation screw (IMFS) implantation is a common procedure in orthognathic surgery (OGS) performed to the temporary maxillary-mandibular fixation and stable bite relationships. The study aims to assess the accuracy of IMFS implantation with a digital guide to reduce the occurrence of root damage. METHODS: This prospective study involved 40 patients undergoing OGS at the Affiliated Hospital of Qingdao University from August 2017 to May 2021. The patients were randomly divided into two groups according to whether the IMFS implantation was with or without digital guide (20 patients in the experimental group and 20 controls). The digital guides used in the experimental group were designed according to a virtual implantation plan and printed using stereolithography. In the control group, IMFSs were directly implanted by a surgeon based on clinical experience. Postoperatively, cone-beam computed tomography was performed to compare root proximity of IMFSs between the two groups and verify the accuracy of IMFS placement. RESULTS: In the experimental group, there was no case of root damage, the incidence of the periodontal ligament (PDL) injured was 22.1%, and 77.9% IMFSs were placed without contacting adjacent anatomic structures. In the control group, the incidence of root damage had been up to 20.8%, 31.7% IMFSs injured the PDL, and only 47.5% IMFSs were placed between the roots (P < 0.001). CONCLUSION: IMFSs can be placed more accurately with surgical guides, reducing the incidence of root and PDL damages.

Comparing Exogenous Methods to Induce Plant-Resistance Against a Bark-Feeding Insect.

Exogenous application of the plant hormone methyl jasmonate (MeJA) can trigger induced plant defenses against herbivores, and has been shown to provide protection against insect herbivory in conifer seedlings. Other methods, such as mechanical damage to seedlings, can also induce plant defenses, yet few have been compared to MeJA and most studies lack subsequent herbivory feeding tests. We conducted two lab experiments to: (1) compare the efficacy of MeJA to mechanical damage treatments that could also induce seedling resistance, (2) examine if subsequent insect damage differs depending on the time since induction treatments occurred, and (3) assess if these induction methods affect plant growth. We compared Scots pine (Pinus sylvestris) seedlings sprayed with MeJA (10 or 15 mM) to seedlings subjected to four different mechanical bark damage treatments (two different bark wound sizes, needle-piercing damage, root damage) and previous pine weevil (Hylobius abietis) damage as a reference treatment. The seedlings were exposed to pine weevils 12 or 32 days after treatments (early and late exposure, hereafter), and resistance was measured as the amount of damage received by plants. At early exposure, seedlings treated with needle-piercing damage received significantly more subsequent pine weevil feeding damage than those treated with MeJA. Seedlings treated with MeJA and needle-piercing damage received 84% less and 250% more pine weevil feeding, respectively, relative to control seedlings. The other treatments did not differ statistically from control or MeJA in terms of subsequent pine weevil damage. For the late exposure group, plants in all induction treatments tended to receive less pine weevil feeding (yet this was not statistically significant) compared to control seedlings. On the other hand, MeJA significantly slowed down seedling growth relative to control and all other induction treatments. Overall, the mechanical damage treatments appeared to have no or variable effects on seedling resistance. One of the treatments, needle-piercing damage, actually increased pine weevil feeding at early exposure. These results therefore suggest that mechanical damage shows little potential as a plant protection measure to reduce feeding by a bark-chewing insect.

Factors Influencing Clinical After Effects of Post Orthognathic Surgery - An Observational Clinical Study.

BACKGROUND: For maintaining the occlusion, screws to anchor bones are needed to be used in transalveolar manner to get the intermaxillary fixation in participants with no preoperative orthodontic treatment or participants with loose or broken appliances. AIMS: The present clinical trial was hence aimed to assess the postoperative complications following orthognathic surgical repair of skeletal malocclusion. MATERIALS AND METHODS: Forty-two participants were divided into two groups (n = 22). In Group I, predrill was done to create the holes in transalveolar position before screw insertion. For Group II, self-cutting screws were used without the drills. The radiographs were then taken to assess the associated root injuries. To evaluate the effect of different steroid doses on the pain, nerve healing, and swelling, the participants were divided into three groups (n = 14). Plate removal and associated factors were also evaluated. Collected data were statistically analyzed. RESULTS: In Group where no predrill was done, no root injuries were seen. Considerably less facial edema was observed in Group II and III compared to control Group I. This difference was statistically significant with a P value of 0.2057. At 1 week, 3 months, and 6-month postoperatively in Group II and Group III, no significant difference was seen. No significant difference in the postoperative pain between the groups was seen (P = 0.85103). Neurosensory Visual Analog Score measurement revealed no significant difference between three groups at 6 months with the P value of 0.81821. CONCLUSION: The present study concludes that risk for the root injury is possessed by the screws that require predrill, whereas the self-drilling screws had no risk for root injury.

Plant DNA Barcode as a Tool for Root Identification in Hypogea: The Case of the Etruscan Tombs of Tarquinia (Central Italy).

Roots can produce mechanical and chemical alterations to building structures, especially in the case of underground historical artifacts. In archaeological sites, where vegetation plays the dual role of naturalistic relevance and potential threat, trees and bushes are under supervision. No customized measures can be taken against herbaceous plants lacking fast and reliable root identification methods that are useful to assess their dangerousness. In this study, we aimed to test the efficacy of DNA barcoding in identifying plant rootlets threatening the Etruscan tombs of the Necropolis of Tarquinia. As DNA barcode markers, we selected two sections of the genes rbcL and matK, the nuclear ribosomal internal transcribed spacer (nrITS), and the intergenic spacer psbA-trnH. All fourteen root samples were successfully sequenced and identified at species (92.9%) and genus level (7.01%) by GenBank matching and reference dataset implementation. Some eudicotyledons with taproots, such as Echium italicum L., Foeniculum vulgare Mill., and Reseda lutea L. subsp. lutea, showed a certain recurrence. Further investigations are needed to confirm this promising result, increasing the number of roots and enlarging the reference dataset with attention to meso-Mediterranean perennial herbaceous species. The finding of herbaceous plants roots at more than 3 m deep confirms their potential risk and underlines the importance of vegetation planning, monitoring, and management on archaeological sites.

Revisiting the Complex Pathosystem of Huanglongbing: Deciphering the Role of Citrus Metabolites in Symptom Development.

Huanglongbing (HLB), formerly known as citrus greening disease, is one of the most devastating bacterial diseases in citrus worldwide. HLB is caused by 'Candidatus Liberibacter asiaticus' bacterium and transmitted by Diaphorina citri. Both 'Ca. L. asiaticus' and its vector manipulate the host metabolism to fulfill their nutritional needs and/or to neutralize the host defense responses. Herein, we discuss the history of HLB and the complexity of its pathosystem as well as the geographical distribution of its pathogens and vectors. Recently, our recognition of physiological events associated with 'Ca. L. asiaticus' infection and/or D. citri-infestation has greatly improved. However, the roles of citrus metabolites in the development of HLB symptoms are still unclear. We believe that symptom development of HLB disease is a complicated process and relies on a multilayered metabolic network which is mainly regulated by phytohormones. Citrus metabolites play vital roles in the development of HLB symptoms through the modulation of carbohydrate metabolism, phytohormone homeostasis, antioxidant pathways, or via the interaction with other metabolic pathways, particularly involving amino acids, leaf pigments, and polyamines. Understanding how 'Ca. L. asiaticus' and its vector, D. citri, affect the metabolic pathways of their host is critical for developing novel, sustainable strategies for HLB management.

Identification of Delia spp. (Robineau-Desvoidy) (Diptera, Anthomyiidae) and its cruciferous hosts in Mexico.

Soil pests of cruciferous crops in Mexico have been gaining importance in recent years; such is the case of Delia spp. (Robineau-Desvoidy) (Diptera, Anthomyiidae), of which, to date, there are no studies on the correct identification of associated species, as well as the range of hosts. In an integrated pest management program, it is essential to know this information to design and implement adequate phytosanitary measures. Plants infested by Delia spp. were collected in the states of Guanajuato, Puebla, and Mexico from June to November 2017 and March to December 2018 in commercial plantations of cruciferous crops (Brassica oleracea L. var. italica, botrytis and capitata), B. napus L., and Raphanus sativus L.) as well as some cruciferous weeds (R. raphanistrum L., Sisymbrium irio L., B. campestris L., Capsella bursa-pastoris L., and Lepidium virginicum L.) in the edges of these crops. The two species found in this study, Delia planipalpis (Stein) and Delia platura (Meigen), identified using male genitalia was corroborated by molecular techniques. Both species emerged from all the sampled hosts, except for C. bursa-pastoris and L. virginicum. The association of the two species in cruciferous crops and weeds, provides valuable information for the management of these insects not only in cruciferous crops but other ones that are strongly attacked by D. platura.

Metatranscriptomic dynamics after Verticillium dahliae infection and root damage in Olea europaea.

BACKGROUND: The olive tree is of particular economic interest in the Mediterranean basin. Researchers have conducted several studies on one of the most devastating disorders affecting this tree, the Verticillium wilt, which causes substantial economic losses in numerous areas. We analyzed metatranscriptomic samples taken from a previous study conducted on leaves and roots of Olea europaea that were infected with Verticillium dahliae. In addition, we also analyzed mechanically damaged roots. The aim of our approach is to describe the dynamics of the root microbiome after severe perturbations. RESULTS: Our results not only describe the dynamics of the microbial community associated with the disturbance, but also show the high complexity of these systems and explain how this can lead to a conflicting assignment of the various types of parasitism observed in a specific organism. CONCLUSIONS: Our findings indicate that this infection, although led by Verticillium, is driven not by a single species, but by a polymicrobial consortium that also includes natural endophytes of the olive tree. This community contains both biotrophic and necrotrophic organisms that alternate and live together during the infection. In addition, opportunistic organisms appear that take profit not from plant tissues, but from new emerging populations of microorganisms. Therefore, this system can be described as a complex biological system composed of different interacting communities. Notably, our work has important considerations when it comes to classifying the type of parasitism of a given species.

Copper pre-exposure reduces AgNP bioavailability to wheat.

Heavy metals in contaminated sites can affect plant responses to emerging contaminates such as engineered silver nanoparticles (AgNPs), but the underlying mechanisms are poorly understood. After 4-day exposure to 0-2.5 mg Cu L-1 hydroponically, Cu concentrations in roots of wheat seedlings (Triticum aestivum L.) increased from 20 ± 3 to 325 ± 58 mg kg-1. Meanwhile, the cell death in root tips, as measured by the uptake of Evans blue stain, increased 1.8-2.8 times in response to Cu exposure. Total thiol contents in roots (including glutathione, cysteine and phytochelatins), as measured by high performance liquid chromatography, increased 1.4 times upon low Cu exposure but decreased 2.2 times upon high Cu exposure. After those wheats were exposed to 10 mg L-1 AgNPs for 8 h, the Ag influx rates decreased 1.3-3.9 times in Cu pre-exposed plants. Together, the cell death in root tips and thiol levels in roots could explain the decreased Ag influx rates of Cu pre-exposed plants. These findings indicate that the bioavailability of AgNPs without consideration of pre-existing metals could be over-estimated.

Nonselective uptake of silver and gold nanoparticles by wheat.

Metallic nanoparticles (NPs) show unique reactivity to crop plants, but the uptake mechanisms remain unclear. We quantitatively evaluated the phytoavailability of particles to wheat (Triticum aestivum L.) in hydroponics upon exposure to AgNPs (15 nm) or AuNPs (13 and 33 nm). Particles were physically separated from the released Ag ions by a dialysis membrane, under which particle-specific uptake of AgNPs could be discerned. Plants did not differentiate AgNPs and AuNPs during particle uptake, with uptake rate constants of 1.1 ± 0.1, 1.2 ± 0.3, and 1.2 ± 0.1 L kg-1 h-1 for AgNPs, AuNPs (13 nm), and AuNPs (33 nm), respectively. We found little effect of particle size (13 or 33 nm AuNPs) or core composition (Ag or Au) on particle bioavailability. Plants stimulated the subsequent uptake of Evans blue stain and showed cell damage in root tips. These results imply similar physiological processes involved in particle-specific uptake of AgNPs and AuNPs. The internalization of particles was further confirmed by single particle inductively coupled plasma mass spectrometry (spICP-MS) and transmission electron microscope-energy dispersive spectrometer (TEM-EDS) analysis. The work here builds the knowledge base for the nature of particle-specific uptake of different NP types by crop plants.

Different Uptake of Metal Dioxide Nanoparticles (Ceria Nanoparticles, Zirconia Nanoparticles and Silica Nanoparticles) by Wheat.

Metal dioxide nanoparticles (NPs) are produced in ever-increasing amounts and widely used in industrial, medical and consumer products. They may pose potential risks to the environment. In this study we quantitatively evaluated the phytoavailability of CeO2NPs, ZrO2NPs and SiO2NPs to wheat (Triticum aestivum L.). Metal dioxide NPs showed distinct differences in uptake, with uptake rate constants of 90.2 ± 9.9, 12.2 ± 2.5, 0.4 ± 0.02 and 0.9 ± 0.1 L kg-1 h-1 for ZrO2NPs, CeO2NPs, SiO2NPs (13 nm) and SiO2NPs (25 nm), respectively. However, such difference cannot be generalized by single factor of NP characteristics and/or root damage. This study provides fundamental information for NP uptake by crop plants.

Effects of orthodontic force on root surface damage caused by contact with temporary anchorage devices and on the repair process.

OBJECTIVE: This study aimed to evaluate the effects of force loading on root damage caused by contact with temporary anchorage devices (TADs) during orthodontic treatment and to examine the repair process 4, 8, and 12 weeks after TAD contact by micro-computed tomography (CT). METHODS: We enrolled 42 volunteers who required bilateral upper first premolar extractions. The experimental study design was as follows. For both first premolars, cantilever springs were placed, and then TADs were immediately inserted between the premolars of all volunteers. According to the removal order of the appliances, the participants were divided into the TAD group (Group T: n = 21, only TAD removal) and the spring group (Group S: n = 21, only spring removal). A split-mouth design was adopted in both groups as follows. For each volunteer, the left premolars were extracted 4, 8, or 12 weeks after TAD-root contact. The right premolars were extracted immediately after contact in both groups (Groups T-C and S-C) and used as positive controls. Resorption volumes and numbers of craters were determined by micro-CT. RESULTS: The numbers of resorption craters were higher in Group T than in Group S at 8 and 12 weeks (p < 0.01). Crater volumes were higher in Group T than in Group S at 4 and 12 weeks (p < 0.01, both). CONCLUSIONS: Root injury was not completely repaired 12 weeks after root-TAD contact, even when the TADs were removed in cases of continuous force application.

An arbuscular mycorrhizal fungus ameliorates plant growth and hormones after moderate root damage due to simulated coal mining subsidence: a microcosm study.

Arbuscular mycorrhizal fungi (AMF) are obligate plant root symbionts delivering a range of benefits to the host plant such as improved nutrient acquisition and resistance to pathogens and abiotic stress. However, whether they can enhance the function of plant root systems damaged due to subsidence caused by excessive coal mining has not been well explored. In the present study, we investigated the effects of AMF using Funneliformis mosseae (FM) as the test fungus on maize (Zea mays L.) growth and hormone levels under different levels of root damage stress by simulating mining subsidence. The results show that plants treated with FM had more shoots, roots, mycorrhizal colonization and higher hyphal density than those without FM under the same simulated mining-induced subsidence conditions. In addition, plants treated with FM also possessed higher N, P, K, Ca, and Mg contents in the shoots and the roots and higher indole-3-acetic acid, gibberellin (GA), and cytokinin (CTK) contents in the roots, indicating that the mycorrhizal association promoted plant biomass and nutrient uptake. FM treatment was no longer beneficial when root damage due to mining-induced subsidence affected more than half of the roots. Soil SOC, AK, and TG were identified as key factors affecting GA, CTK, IAA, and ABA, and AMF can alter plant hormones directly via the hyphae and indirectly by altering soil physicochemical properties under root damage stress. Overall, our results provide baseline data for assessing the biological reclamation effects of AMF on coal mining-induced subsidence.

Phytotoxicity of wear debris from traditional and innovative brake pads.

Traffic-related emissions include gas and particles that can alter air quality and affect human and environmental health. Limited studies have demonstrated that particulate debris thrown off from brakes are toxic to higher plants. The acute phytotoxicity of brake pad wear debris (BPWD) investigated using cress seeds grown in soil contaminated with increasing concentrations of debris. Two types of pads were used: a commercially available phenol based pad and an innovative cement-based pad developed within of the LIFE+ COBRA project. The results suggested that even through the BPWD generated by the two pads were similar in and morphology, debris from traditional pads were more phytotoxic than that from cementitious pads, causing significant alterations in terms of root elongation and loss of plasma membrane integrity.