Root Tip Cells Research Articles

Real-time detection of the nanoparticle induced phytotoxicity in rice root tip through the visible red emissions of Eu3+ ions.

Phytotoxicity is one of the most important factors involved in the reduction of crop production. With the introduction of NaBiF4 nanoparticles, the effect of the particle size (>50 nm) on rice development was systematically studied. Through the exogenous treatment of multiple concentrations of nanoparticles, the primary root length, lateral root number, and lateral root length were significantly inhibited under higher content of nanoparticles, but more crown root formation was induced, which might be due to phytotoxicity. With the help of the red emission of the Eu3+-activated NaBiF4 nanoparticles, we could infer that the nanoparticles were accumulated in the root tip cells in the division and elongation zone but not in the mature region. Additionally, the investigation on the influence of the studied nanoparticles on the gene level and the expression of phytotoxicity related genes was performed to further identify the effect of the nanoparticles on the rice root development. These results potentially explain the effect of larger nanoparticles on phytotoxicity in the plant roots.

Determination of the Genotoxicity of the Soil in the Aydın Region Irrigated by Büyük Menderes River by the Allium Test System

Nowadays, one of the most important problems is environmental pollution. Environmental pollution in the Büyük Menderes River-basin, which is one of the agricultural fields in Turkey, has reached important dimensions. B. Menderes River which waters B. Menderes River-basin and fields around it is contaminated by various sources.In this study the genotoxicity of the soil samples taken from three different regions in two different months (September 2006 and March 2007) in the Aydın region of B. Menderes River-basin was researched with the Allium test.The soil samples were taken from the lands watered by the B. Menderes River and Çine Stream; the fields near the B. Menderes Bridge (on the Muğla main road), the Çine Stream, and the Koçarlı Bridge in September and March. 25%, 50%, 100% concentrations were prepared diluting these samples and onions (Allium cepa L.) were rooted. At the end of the studies, the decrease in the mitotic index was found to be statistically important according to the control in all the doses except 25% of the Çine doses in September and March. The study soil samples taken from the three different regions in two different months caused structural chromosomal aberrations such as anaphase bridge, fragment, stickiness, and polar deviation in the Allium cepa L. root tip cells. It has been emphasized that the difference in all the doses except for 25% Menderes, 25% Koçarlı, 50% doses in September and 25% Çine, 25% Menderes, 25%, 25% Koçarlı, Koçarlı, 50% doses in March are important according to the control in the total chromosomal aberrations.

Chromosomal Disturbances during Mitotic Activity of Root Tip Cells in Allium by Certain Commonly Used Antibiotics

Chromosomal Disturbances during Mitotic Activity of Root Tip Cells in Allium by Certain Commonly Used Antibiotics

Genotoxicity effects of silver nanoparticles on wheat (Triticum aestivum L.) root tip cells

The distribution and use of nanoparticles have rapidly increased over recent years, but the available knowledge regarding their mode of action, ecological tolerance and biodegradability remains insufficient. Wheat (Triticum aestivum L.) is the most important crop worldwide. In the current study, the effects of silver nanoparticles (AgNPs) obtained from two different sources, namely, green and chemical syntheses, on chromosomal aberrations and cell division were investigated. Wheat root tips were treated with four different AgNP concentrations (10, 20, 40 and 50 ppm) for three different exposure durations (8, 16 and 24 h), and the different concentrations of the nanoparticles were added to the tested grains until the root lengths reached 1.5–2 cm. For each concentration, the mitotic indexes (%) were obtained from an analysis of ~ 2000 cells. The treated root-tip cells exhibited various types of chromosomal aberrations, such as incorrect orientation at metaphase, chromosomal breakage, metaphasic plate distortion, spindle dysfunction, stickiness, aberrant movement at metaphase, fragmentation, scattering, unequal separation, scattering, chromosomal gaps, multipolar anaphase, erosion, and distributed and lagging chromosomes. These results demonstrate that the root tip cells of wheat can readily internalize the AgNPs and that the internalized AgNPs can interfere with the cells’ normal function.

Analysis of aluminum toxicity in Hordeum vulgare roots with an emphasis on DNA integrity and cell cycle.

Barley is one of the cereals that are most sensitive to aluminum (Al). Al in acid soils limits barley growth and development and, as a result, its productivity. The inhibition of root growth is a widely accepted indicator of Al stress. Al toxicity is affected by many factors including the culture medium, pH, Al concentration and the duration of the treatment. However, Al can act differently in different species and still Al toxicity in barley deserves study. Since the mechanism of Al toxicity is discussed we cytogenetically describe the effects of different doses of bioavailable Al on the barley nuclear genome—mitotic activity, cell cycle profile and DNA integrity. At the same time, we tested an established deep-water culture (DWC) hydroponics system and analyzed the effects of Al on the root system parameters using WinRHIZO software. We demonstrated the cytotoxic and genotoxic effect of Al in barley root cells. We showed that Al treatment significantly reduced the mitotic activity of the root tip cells and it also induced micronuclei and damaged nuclei. The DNA-damaging effect of Al was observed using the TUNEL test. We define the inhibitory influence of Al on DNA replication in barley. Analysis with the labelling and detection of 5-ethynyl-2‘-deoxyuridin (EdU) showed that the treatment with Al significantly decreased the frequency of S phase cells. We also demonstrated that Al exposure led to changes in the cell cycle profile of barley root tips. The delay of cell divisions observed as increased frequency of cells in G2/M phase after Al treatment was reported using flow cytometry.

Reactive oxygen species triggering systemic programmed cell death process via elevation of nuclear calcium ion level in tomatoes resisting tobacco mosaic virus

Programmed cell death (PCD) plays a positive role in the systemic response of plants to pathogen resistance. It has been confirmed that local tobacco mosaic virus (TMV) infecting tomato leaves can induce systemic PCD process in root-tip tissues. But up to now the underlying physiological mechanisms are poorly understood. This study focused on the detailed investigation of the physiological responses of root-tip cells during the initiation of systemic PCD. Physiological, biochemical examination and cytological observation showed that 1 day post-inoculation (dpi) of TMV inoculation there was an increase in calcium fluorescence intensity in root tip tissue cells. Then at 2 dpi, 4 dpi, 8 dpi and 15 dpi, the fluorescence intensity of calcium ion continued to increase. However, at 5 dpi, the reactive oxygen species (ROS) began to accumulate in the root-tip cells. And finally at 20 dpi, the obvious PCD reaction was detected. In addition, the experimental results also showed that the above process involved the elevation of two types of intracellular Ca2+, including cytoplasmic calcium ([Ca2+]cyt) and nuclear calcium ([Ca2+]nuc). The [Ca2+]cyt, as a pilot signal could lead to the subsequent elevation of intracellular ROS concentration. Then, the high levels of ROS stimulated an increase of [Ca2+]nuc and eventually caused PCD reactions in the root-tip tissues. In particular, the high level of nuclear calcium is an essential mediator in systemic PCD of plants.

Volatile allelochemicals of Chenopodium ambrosioides L. induced mitochondrion-mediated Ca2+-dependent and Caspase-dependent apoptosis signaling pathways in receptor plant cells

This study aims to explain the mechanism of action of allelochemical effect of Chenopodium ambrosioides L. volatile oil on mitochondrial characteristics of receptor plants. This study chose maize (Zea mays L.), which is widely grown in C. ambrosioides invaded field as the receptor plant, and investigated the allelochemical effect of C. ambrosioides volatile oil and its two main components (α-terpinene and cymene) on maize root tip cells using a suspended gas method and TdT-mediated dUTP Nick-End Labeling (TUNEL) assays. The allelochemical effect on the relative expression of the apoptosis-associated type II Metacaspase gene ZmMCII was measured by quantitative real time polymerase chain reaction (qRT-PCR). The allelochemical effect on mitochondrial characteristics was analyzed by staining assays. The results showed that applications of C. ambrosioides volatile oil, α-terpinene, and cymene on maize root tip cells caused membrane lipid peroxidation, increased mitochondrial H2O2 and MDA contents, decreased mitochondrial membrane potential, released mitochondrial Cyt c and Ca2+ into the cytoplasm, and increased cytosolic Ca2+ level and expression of the type II Metacaspase gene ZmMCII. These apoptotic effects were time-dependent. It suggested that C. ambrosioides volatile allelochemicals induced accumulation of reactive oxygen species (ROS) and triggered mitochondrion-mediated Ca2+- and Caspase-dependent apoptosis signaling pathways in receptor plant cells.

Genetic Toxicity of Solidago canadensis

Solidago decurrens is a plant of Asteraceae, which is mainly produced in southern China. It is widely used cut flower material. It is known as the malignant weed Solidago canadensis (Solidago canadensis) with the genus Flora, so its application of ecological security has been a big debate. In this paper, the allelopathic effect of the water extract of Solidago macrophylla was studied by using the micronucleus technique of Vicia faba root tip as the experimental material. The aim of this study was to analyze the genetic toxicity of Solidago canadensis. The results showed that: (1) The water extract of Solidago canadensis could decrease the mitotic index and interfere with the normal process of mitosis, where the decreased rate was positively correlated with the concentration of water extract and treatment time. (2) The effects of water extract on the root tip of Vicia faba were significant increases with time and concentration effect (3) Achilla glauca extract could make the chromosome bridge, chromosome fragment, chromosome lag in the root tip cells of Vicia faba and increase in micronucleus rate. The results showed that the water extract of Solidago canadensis had different degree of inhibition and damage to silkworm root tip cells; it also had some genetic toxicity and rapid diffusion ability.

Preliminary Bioinformatic Analysis of Gallus gallus (Chicken) CD8a Gene

The experimental object of this study is Gallus gallus (chicken) CD8a gene. In this study, we performed sequence analysis of CD8a gene and analyzed the primary structure, secondary structure and tertiary structure of CD8a encoded protein by using bioinformatics. Through the analysis, we concluded that the sequence length is 648bp with various restriction sites identified, which is similar to CD8a of other species in Galliformes order. The sequence encodes a total of 216 amino acids. The amino acids have low hydrophobicity, with 12 phosphorylation sites and a transmembrane region, and no signal peptide. The protein secondary structure mainly consists ofαspiral, accounting for 22.69%; extension chain, accounting for 15.74%; random coil, accounting for 61.57 %, in non-continuous distribution. The relationship between CD8a and other species homologous sequences is basically consistent with the establishment of the system tree by the establishment of three trees. n the root tip cells of Vicia faba and increase in micronucleus rate. The results showed that the water extract of Solidago canadensis had different degree of inhibition and damage to silkworm root tip cells; it also had some genetic toxicity and rapid diffusion ability.

Homology bioinformatics analysis of IPA1 gene in higher plants

IPA1 gene controlled paddy has increased in height, sturdy stem, number of tillers decreased, grains per panicle and dry grains weight increased significantly. In this study, the homology of IPA1 gene in 26 types of plant from 15 families was analyzed, and thus constructed its phylogenetic tree. The results of phylogenetic tree construction based on its amino acid sequence showed that the species from the same family, such as Gramineae, Rosaceae and Palmaceae, were well clustered for different branches and had high support rates. Furthermore, we constructed the phylogenetic tree based on its CDS sequence, and the species of Gramineae was well clustered, and the support rate was 100%. Our results indicate that IPA1 has high homology in higher class of plants, especially in the Gramineae, which is of great significance for us to further study the yield of rice and other gramineous species.s with time and concentration effect (3) Achilla glauca extract could make the chromosome bridge, chromosome fragment, chromosome lag in the root tip cells of Vicia faba and increase in micronucleus rate. The results showed that the water extract of Solidago canadensis had different degree of inhibition and damage to silkworm root tip cells; it also had some genetic toxicity and rapid diffusion ability.

Chromosomal and Nuclear Alterations in the Root Tip Cells of Vicia faba Induced by Sodium Chloride.

Despite the well-known toxic effect of chloride sodium (NaCl), only few studies analyze its genotoxic effect on crops. Micronucleus assay is an efficient tool for the measure of chromosomal DNA damages. Based on this test, the effects of salt on micronucleus induction, and on chromosome and nucleus changes, were investigated in Vicia faba root tips treated with NaCl (electrical conductivity = 25 dS/m) during 24 hours. V. faba meristematic cells showed a significant increase in the number of micronuclei compared with the control. Micronucleus size varied from small to large and appeared at different stages of mitosis. Moreover, different chromosomal aberrations like breaks, bridges, rings, vagrant, and lagging chromosomes, were observed in the metaphase, the anaphase, and the telophase. In addition, nuclear alterations in the interphase were characterized by the presence of binucleated cells, strap nuclei with lesions, hyperchromasia, buds, and nuclei with irregular shapes and lesions.

Cadmium’s Effect on the Organization of Microtubular Cytoskeleton in Root Tips Cells of Salix matsudana Koidz

Cadmium’s Effect on the Organization of Microtubular Cytoskeleton in Root Tips Cells of Salix matsudana Koidz

Beryllium Stress-Induced Modifications in Antioxidant Machinery and Plant Ultrastructure in the Seedlings of Black and Yellow Seeded Oilseed Rape.

Beryllium (Be) could be a threatening heavy metal pollutant in the agroecosystem that may severely affect the performance of crops. The present study was conducted to evaluate the toxic effects of Be (0, 100, 200, and 400 μM) on physiological, ultrastructure, and biochemical attributes in hydroponically grown six-day-old seedlings of two cultivars of Brassica napus L., one tolerant (ZS 758, black seeded) and one sensitive (Zheda 622, yellow seeded). Higher Be concentrations reduced the plant growth, biomass production, chlorophyll contents, and the total soluble protein contents. A significant accumulation of ROS (H2O2, OH−) and MDA contents was observed in a dose-dependent manner. Antioxidant enzymatic activities including SOD, POD, GR, APX, and GSH (except CAT) were enhanced with the increase in Be concentrations in both cultivars. Relative transcript gene expression of above-mentioned antioxidant enzymes further confirmed the alterations induced by Be as depicted from higher involvement in the least susceptible cultivar ZS 758 as compared to Zheda 622. The electron microscopic study showed that higher level of Be (400 μM) greatly damaged the leaf mesophyll and root tip cells. More damage was observed in cultivar Zheda 622 as compared to ZS 758. The damage in leaf mesophyll cells was highlighted as the disruption in cell wall, immature nucleus, damaged mitochondria, and chloroplast structures. In root tip cells, disruption in Golgi bodies and damage in cell wall were clearly noticed. As a whole, the present study confirmed that more inhibitory effects were recorded in yellow seeded Zheda 622 as compared to black seeded ZS 758 cultivar, which is regarded as more sensitive cultivar.

MutS-Homolog2 silencing generates tetraploid meiocytes in tomato (Solanum lycopersicum).

MSH2 is the core protein of MutS‐homolog family involved in recognition and repair of the errors in the DNA. While other members of MutS‐homolog family reportedly regulate mitochondrial stability, meiosis, and fertility, MSH2 is believed to participate mainly in mismatch repair. The search for polymorphism in MSH2 sequence in tomato accessions revealed both synonymous and nonsynonymous SNPs; however, SIFT algorithm predicted that none of the SNPs influenced MSH2 protein function. The silencing of MSH2 gene expression by RNAi led to phenotypic abnormalities in highly silenced lines, particularly in the stamens with highly reduced pollen formation. MSH2 silencing exacerbated formation of UV‐B‐induced thymine dimers and blocked light‐induced repair of the dimers. The MSH2 silencing also affected the progression of male meiosis to a varying degree with either halt of meiosis at zygotene stage or formation of diploid tetrads. The immunostaining of male meiocytes with centromere localized CENPC (centromere protein C) antibody showed the presence of 48 univalent along with 24 bivalent chromosomes suggesting abnormal tetraploid meiosis. The mitotic cells of root tips of silenced lines showed diploid nuclei but lacked intervening cell plates leading to cells with syncytial nuclei. Thus, we speculate that tetraploid pollen mother cells may have arisen due to the fusion of syncytial nuclei before the onset of meiosis. It is likely that in addition to mismatch repair (MMR), MSH2 may have an additional role in regulating ploidy stability.

Impact of Engineered Si Nanoparticles on Seed Germination, Vigour Index and Genotoxicity Assessment via DNA Damage of Root Tip Cells in Lens culinaris

Impact of Engineered Si Nanoparticles on Seed Germination, Vigour Index and Genotoxicity Assessment via DNA Damage of Root Tip Cells in Lens culinaris

Stress-Generated Free Radicals Detected by Electron Paramagnetic Resonance Spectroscopy with Nitrone Spin Trap in Vicia faba Root

Electron paramagnetic resonance (EPR) spectroscopy is a promising technique for detection and quantification of short-lived free radicals in biological systems. In the present investigation, root of Viciafaba seedlings were subjected to 0.5 mM (T1) and 1 mM (T2) sodium azide (NaN3) in hydroponic medium. The stress-generated free radicals (superoxide and hydroxyl free radicals) in the root tips of the seedlings were analyzed by EPR spectroscopy using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) nitrone spin. Single cell gel electrophoresis (comet assay) and mitotic index along with the spectrophotometric measurement of the two major antioxidant enzymes, namely, superoxide dismutase (SOD) and catalase (CAT), in combination with analysis of lipid peroxidation product, malondialdehyde (MDA), were done to validate the EPR results. Data obtained from comet assay of root tip cells revealed significant increase in the olive moment in T1 and T2 as compared to control. Decreased mitotic index in T2 (60.63 ± 7.74%) as compared to control (88.23 ± 1.01%) in these cells as a consequence of increased reactive oxygen species (ROS) was depicted. Furthermore, the decrease in the activity of major antioxidant enzymes, SOD and CAT justified the intensified DMPO-OH specific peaks in T2 as compared to control obtained in the EPR spectra. The results establish that EPR spectroscopy can be used successfully at room temperature to monitor changes in the production of free radicals (combined superoxide and hydroxyl free radicals) in plant tissues using DMPO as a spin trap.

Biodegradation of Azure-B dye by Serratia liquefaciens and its validation by phytotoxicity, genotoxicity and cytotoxicity studies

The azo dyes in textile industry are a major source of environmental pollution and cause serious threat to aquatic flora and fauna. The present study aims to evaluate the potential of previously isolated lignin peroxidase (LiP) enzyme producing Serratia liquefaciens in degradation of Azure-B (AB) dye. S. liquefaciens showed rapid decolourisation of AB dye (100 mg L−1) in mineral salt medium (MSM) supplemented with 0.2% glucose and yeast extract, and more than 90% dye decolourisation was observed at 48 h when incubated at 30 °C. Decolourisation conditions were optimized by Response Surface Methodology (RSM) using Box-Behnken Designs (BBD). The dye degradation was further confirmed by ATR-FTIR and GC-MS analysis. Toxicological studies of untreated (UT) and bacterial treated (BT) AB dye solutions were studied by using phytotoxicity, genotoxicity and cytotoxicity endpoints. Phytotoxicity assay using Vigna radiata indicated that bacterial treatment led to detoxification of AB dye. Genotoxicity assay with Allium cepa showed that pure AB dye solutions significantly reduced mitotic index (MI) and induced various chromosomal abnormalities (CAs) like c-mitosis, stickiness, chromosome break, anaphase bridges, vagrant chromosomes and binucleated and micronucleated cell in the root tip cells, whereas, bacterial treated solutions induced relatively less genotoxicity in nature. Improved cell survivability (%) was also noted in kidney cell line (NRK-52E) after S. liquefaciens treated dye solutions than the pure dye solutions. The findings suggest that S. liquefaciens could be a potential bacterium for azo dye degradation, as it is effective in lowering of toxic effects of AB dye.

Disruption of actin filaments in Zea mays by bisphenol A depends on their crosstalk with microtubules

Bisphenol A (BPA) is a widespread environmental pollutant, reportedly harmful to living organisms. In plant cells, BPA was shown to disrupt microtubule (MT) arrays and perturb mitosis, but its effects on filamentous actin (F-actin) have not been explored. Here we studied the effects of BPA on actin filaments (AFs) in meristematic root tip and leaf cells of Zea mays, by fluorescent labeling and confocal microscopy. Considering the typical dynamic interaction between MTs and AFs, the effects on these two essential components of the plant cytoskeleton were correlated. It was found that BPA disorganized rapidly AFs in a concentration- and time-dependent manner. The fine filaments were first to be affected, followed by the subcortical bundles, resulting in rod- and ring-like conformations. The observed differences in sensitivity between protodermal and cortex cells were attributed to the deeper location of the latter. Depolymerization or stabilization of MTs by relevant drugs (oryzalin, taxol) revealed that AF susceptibility to BPA depends on MT integrity. Developing leaves required harder and longer treatment to be affected by BPA. Ontogenesis of stomatal complexes was highly disturbed, arrangement of AFs and MT arrays was disordered and accuracy of cell division sequence was deranged or completely arrested. The effect of BPA confirmed that subsidiary cell mother cell polarization is not mediated by F-actin patch neither of preprophase band organization. On the overall, it is concluded that AFs in plant cells constitute a subcellular target of BPA and their disruption depends on their crosstalk with MTs.

Mechanism underlying rapid responses to boron deprivation in Arabidopsis roots

ABSTRACTTransferring hydroponically grown Arabidopsis plants (Arabidopsis thaliana L.) to boron (B)-free medium kills the cells in root tips within an hour. To understand the mechanism underlying the induced rapid cell death, the Arabidopsis response to B deprivation was characterized using inhibitors of presumably involved cellular processes. The results suggest that stretching of the plasma membrane and the influx of calcium ions through mechanosensitive channels triggered the responses and that reactive oxygen species were overproduced under B-deprived condition. In addition, nitric oxide was observed to be involved in cell death, suggesting that Arabidopsis root cells undergo programmed cell death upon B deprivation. RNA sequencing analysis revealed that B deprivation induced transcriptome changes that resembled pathogen-induced responses. In summary, we speculate that B deprivation induces hypersensitive responses in Arabidopsis roots as a response to defective cell wall structures.

Nitric Oxide Inhibits Al-Induced Programmed Cell Death in Root Tips of Peanut (Arachis hypogaea L.) by Affecting Physiological Properties of Antioxidants Systems and Cell Wall.

It has been reported that nitric oxide (NO) is a negative regulator of aluminum (Al)-induced programmed cell death (PCD) in peanut root tips. However, the inhibiting mechanism of NO on Al-induced PCD is unclear. In order to investigate the mechanism by which NO inhibits Al-induced PCD, the effects of co-treatment Al with the exogenous NO donor or the NO-specific scavenger on peanut root tips, the physiological properties of antioxidants systems and cell wall (CW) in root tip cells of NO inhibiting Al-induced PCD were studied with two peanut cultivars. The results showed that Al exposure induced endogenous NO accumulation, and endogenous NO burst increased antioxidant enzyme activity in response to Al stress. The addition of NO donor sodium nitroprusside (SNP) relieved Al-induced root elongation inhibition, cell death and Al adsorption in CW, as well as oxidative damage and ROS accumulation. Furthermore, co-treatment with the exogenous NO donor decreased MDA content, LOX activity and pectin methylesterase (PME) activity, increased xyloglucan endotransglucosylase (XET) activity and relative expression of the xyloglucan endotransglucosylase/hydrolase (XTH-32) gene. Taken together, exogenous NO alleviated Al-induced PCD by inhibiting Al adsorption in CW, enhancing antioxidant defense and reducing peroxidation of membrane lipids, alleviating the inhibition of Al on root elongation by maintaining the extensibility of CW, decreasing PME activity, and increasing XET activity and relative XTH-32 expression of CW.