Root Tip Meristems Research Articles

Cytogenetic and cytological analysis of advanced genetic material of cape gooseberry Physalis peruviana for use in plant breeding

The cape gooseberry, Physalis peruviana L., is a crop that is transitioning from a semi-wild rural food source to becoming an international export commodity fruit deserving of greater attention from the scientific community, producers, policy makers and opinion makers. Despite its importance, the crop has serious technological development challenges, mainly associated with the limited supply of genetically improved materials for producers and consumers. In the present study, the level of ploidy of 100 genotypes of gooseberry from a working collection was determined by counting the number of chromosomes and chloroplasts, to include them in the breeding program. The number of chromosomes in dividing cells of root-tip meristems, as well as the number of chloroplasts per guard cell, from plants grown in vitro and ex vitro conditions were determined. Haploid with 24 chromosomes, doubled haploid-tetraploid with 48 chromosomes, aneuploid (44 and 49 chromosomes) and mixoploid genotypes with 36 to 86 chromosomes were found. The number of chloroplasts / cell guard ranged from 4-8, 6-16, 7-16 and 9-21 for the haploid, aneuploid, doubled haploid-tetraploid and mixoploid genotypes, respectively. Evidence of a high cytogenetic diversity in the evaluated genotypes.

Genotoxic Effects of Heavy Metals on Mitotic Chromosomes of Trigonella Foenum-Graecum L.

Lead, cadmium, and copper are common environmental pollutants in most industrialized countries. Soil with heavy metal pollution has raised concern in recent years due to its possible destructive effects on plants system. In the present investigation, we studied the genotoxic effect of lead, cadmium, and copper on mitotic chromosomes of Trigonella foenum-graecum L. for the first time. The root tips of T. foenum-graecum were treated with four graded concentrations (viz. 50, 100, 150, and 200 ppm) of lead, cadmium, and copper. After hydrolyzing the root end in hydrochloric acid solution, they were stained with acetocarmine. After squashing the root end, they were studied under a microscope. To this end, the mitotic index (MI) and the total percentage of abnormality (TAP%) were analyzed. Studying of the root end of T. foenum-graecum showed that this plant is diploid and its chromosomal base number is 2x=2n=16. Cytological monitoring revealed that Pd, Cd, and Cu exhibit mitodepressive behaviors at higher concentrations. Moreover, the mitotic index decreases, but the incidence of different anomalies, such as sticky chromosome, c-mitosis, micronucleus, laggard chromosome, bridge, and precocious movement, increase through increasing heavy metal concentration. Among the mitotic abnormalities observed in all treatments, the highest percentage was related to the sticky chromosome. The highest genotoxic potential was observed in the lead, followed by cadmium and copper. The results showed that heavy metal pollution led to a significant MI reduction and TAP% increase in root tip meristems of T. foenum-graecum. This should be considered as a risk warning of the environmental pollution on plants, especially medicinal plants.

Antioxidant, Cytotoxic, and Antibacterial Activities of the Selected Tibetan Formulations Used in Gandaki Province, Nepal.

Materials and Methods An open-ended and semistructured questionnaire was used for an ethnomedicinal survey of the Tibetan formulations practiced in four Tibetan refugee settlements in Gandaki Province, Nepal. Based on the ethnomedicinal survey data, commonly used nine formulations were selected (Aru-18, Basam, Dadue, Dashel, Mutik-25, Raab Ga Yangzin Tea, Serdok-11, Sugmel-10, and Yungwa-4) to test biological activities. Antioxidant activity was evaluated using the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging method. The cytotoxicity was examined by using the Allium cepa L. root tip meristem model. Similarly, the antibacterial effect was assessed by using well diffusion and broth dilution methods. Results An ethnomedicinal survey showed a total of 52 Tibetan formulations were generally used by respondents for common diseases such as stomach disorders, diabetes, and migraine. From the antioxidant activity test, Sugmel-10 showed the highest DPPH free-radical-scavenging activity (IC50 1.8 μg/ml) and Yungwa-4 showed the lowest activity (IC50 5.2 μg/ml). Also, from the cytotoxic activity, the A. cepa root meristem model exhibited significant dose- and time-dependent growth suppression in Basam, Dadue, Mutik-25, and Serdok-11 as compared with cyclophosphamide standard drug. Similarly, Basam showed a good antibacterial effect having MIC 20 mg/ml and MBC 100 mg/ml against Enterococci faecalis. Conclusion. Research showed that Tibetan people preferred Tibetan formulations for the treatment and mitigation of several diseases. The result of antioxidant, cytotoxic, and antibacterial activities experimentally justified the ethnomedicinal value of nine common formulations (Aru-18, Basam, Dadue, Dashel, Mutik-25, Raab Ga Yangzin Tea, Serdok-11, Sugmel-10, and Yungwa-4). To the best of our knowledge, this study was performed for the first time in Nepal. Results from this preliminary study open the door to the scientific world to perform extensive pharmacological studies for designing and developing new therapeutic agents.

Mutagenic potential of Gamma rays on Somatic cell division and morphological parameters in Foeniculum vulgare Mill.

Mutagenesis involving ionizing radiation has been widely used for alteration in genetic constituents to increase the variability at gene level in a very small fraction of time. But, attempts to induce genetic variability in fennel for agronomically important trait are very limited. Narrow genetic base is the main hindrance in handling the conventional breeding in Fennel . Thus, main idea of this study is to generate genetic variability in Ajmer fennel-2 variety of Foeniculum vulgare Mill. by using the most potent physical mutagen i.e. gamma rays. The seeds were exposed to different doses of gamma rays viz. 5, 10, 15, 20 and 25Kr, respectively, along with control to analyze the effect of gamma rays on meristematic root tips. Germination and survival percentage were significantly affected in response to ionizing potential of gamma rays and a dose dependent decline was observed in both the parameters. Plant height, shoots, root length and days of flowering were also affected by gamma rays and a considerable increment was achieved at lowest dose with respect to control. As the dose of gamma ray increases, the rate of Active Mitotic Index declines. The irradiated seeds show numerous chromosomal variations such as; scattering, stickiness, bridge formation etc which are computed in the form of Total Abnormality Percentage.

Cytotoxic, Antimitotic, DNA Binding, Photocatalytic, H2O2 Sensing, and Antioxidant Properties of Biofabricated Silver Nanoparticles Using Leaf Extract of Bryophyllum pinnatum (Lam.) Oken.

Bryophyllum pinnatum is a perennial herb traditionally used in ethnomedicine. In the present report, silver nanoparticles (AgNPs) were synthesized using B. pinnatum leaf extract. BP-AgNPs were confirmed following UV-Vis spectroscopy with SPR peak at 412 nm and further characterized by FTIR, XRD, SEM-EDX, and TEM. Microscopic images confirmed the spherical shape and ~15 nm average size of nanostructures. BP-AgNPs were evaluated for photocatalytic degradation of hazardous dyes (methylene blue and Rhodamine-B) and showed their complete reduction within 100 and 110 min., respectively. BP-AgNPs have emerged as a unique SPR-based novel sensor for the detection of H2O2, which may deliver exciting prospects in clinical and industrial areas. DPPH and ABTS free radical scavenging activity were studied with respective IC50 values of 89 and 259 μg/mL. A strong intercalating interaction of CT-DNA with BP-AgNPs was investigated. Observed chromosomal abnormalities confirm the antimitotic potential of BP-AgNPs in the meristematic root tip. The cytotoxicity of BP-AgNPs against B16F10 (melanoma cell line) and A431 (squamous cell carcinoma cell line), was assessed with respective IC50 values of 59.5 and 96.61 μg/ml after 24 h of treatment. The presented green synthetic approach provides a novel and new door for environmental, industrial, and biomedical applications.

A Panax notoginseng Root Tip Meristem Biosensor and Its Sensing Kinetics for Five Important Nitrogen Nutrients

Plants absorb nitrogen mainly through their roots. Nitrogen sensing is required for the absorption and transport of different nitrogen nutrients. In this study, we constructed biosensors with immobilized Panax notoginseng root tip meristems based on a three‐electrode system and successfully determined the kinetics of the interactions between the P. notoginseng root tip meristems and five important nitrogen nutrients, namely, urea, sodium nitrate, sodium glutamate, disodium inosinate, and disodium guanylate. We discovered that the biosensor’s sensing kinetics was similar to the enzyme–substrate kinetics, and the receptor–ligand interconnected allosteric interaction constant Ka (mol/L), analogous to the Michaelis constant, was calculated. The result showed that the root tip meristems of two‐ to four‐year‐old P. notoginseng plants had a higher capacity to sense inorganic nitrogen nutrients (sodium nitrate and urea) than the three organic nitrogen nutrients. The ability of the plants to sense inorganic nitrogen nutrients decreased with an increase in plant age. The sensing sensitivity of four‐year‐old P. notoginseng plants to disodium inosinate and disodium guanylate was 100‐ to 10,000‐fold lower than that of the two‐ and three‐year‐old plants. Additionally, the capability to sense sodium glutamate decreased initially and then increased with an increase in plant age. The biosensors reached an ultra‐sensitive level (1 × 10−22 mol/L) in sensing the five nitrogen nutrients and exhibited advantages such as good stability and reproducibility, low cost, a simple structure, and a rapid response, providing a new approach for quantitative determination of the capability of plants to sense different nitrogen nutrients.

GISH: Resolving Interspecific and Intergeneric Hybrids.

Genomic in situ hybridization (GISH) is an invaluable cytogenetic technique which enables the visualization of whole genomes in hybrids and polyploidy taxa. Total genomic DNA from one or two different species/genomes is used as a probe, labeled with a fluorochrome, and directly detected on mitotic chromosomes from root tip meristems. In sugarcane and sugarcane hybrids, we were able to characterize interspecific hybrids of two closely related species as well as intergeneric hybrids of two closely related genera.

Cytogenetical and Physiological Effects of L-tryptophan in Onion (Allium cepa L.) Exposed to Salt Stress

In this study, 10 mg L–1 L-tryptophan effects on the seedling growth (fresh weight, radicle length and radicle number), seed germination, chromosomal aberrations and mitotic activity in Allium cepa L. germinated in salinity (0.175 M NaCl) conditions were investigated. In only L-tryptophan medium, the radicle length and radicle number of the seedlings were partially reduced compared to the control seedlings grown in the pure water medium, the germination percentage and fresh weight indicate statistically the same values as the control. Moreover, the chromosomal aberrations and mitotic index in the root tip meristem cells of Allium cepa seeds germinated in alone L-tryptophan medium showed increase compared to the control seeds germinated in the pure water medium. On the other hand, salt stress significantly inhibited the germination rate, radicle length, radicle number and fresh weight of Allium cepa L. In addition, it important reduced the mitotic index (activity) and increased the chromosomal aberrations in root tip meristems of the seeds. Nevertheless, the inhibitory effects of salt stress on all the mentioned parameters were dramatically alleviated by L-tryptophan application. The germination percentage, radicle length, radicle number, fresh weight, mitotic index and chromosomal aberrations of the seedlings grown in 0.175 M salinity were 23%, 10.3 mm, 12.7, 7 g, 1.2 and 17% respectively, while these values became 77%, 15.3 mm, 16.7, 15.2 g, 11.6 and 14.6% in the seedlings treated with 10 mg L–1 L-tryptophan.

ASSESSMENT OF ANTIOXIDANT POTENTIAL AND ANTIGENOTOXICITY ANALYSIS THROUGH HYDROGEN PEROXIDE-INDUCED OXIDATIVE STRESS IN TERMINALIA PANICULATA ROTH

Objective: The present study is mainly focused on the antigenotoxicity and antioxidant potential of the fruit extract of an important dye yielding plant Terminalia paniculata Roth.
 Methods: Genoprotective activity of the fruit extract was studied by Allium cepa root tip assay. Three modes of treatment were used to perform the antigenotoxicity, that is, pre-treatment, post-treatment, and simultaneous treatment. For the study of antioxidant potential, four different assays were performed.
 Results: Antigenotoxicity studies revealed the protective role of the extract in chromosomal aberrations induced by 2% hydrogen peroxide (H2O2) on A. cepa root tip meristem. The fruit extract showed a significant modulatory effect by means of an inhibition percentage and also it showed a characteristic reversing of chromosomal aberrations induced by H2O2. While in the case of antioxidant activity, the plant extract showed an appreciable antioxidant potential. Four different assays were used to determine the antioxidant potential of T. paniculata. Of these 2,2-diphenyl-1-picryl-hydrazyl-hydrate radical scavenging activity revealed almost equal effect to that of the standard.
 Conclusions: In the present investigation, it has been found that the important dye yielding plant T. paniculata has a significant role in various commercial industries such as food, cosmetics, clothes, and pharmaceutics due to its efficient protective role.

Influence of He-Ne laser irradiation and cadmium and lead on changes in cell cycles at Zea mays L.

The aim of the study was to investigate the effect of red radiation emitted by helium-neon laser (He-Ne) with a wavelength λ = 632.8 nm and trace elements: cadmium (Cd) and lead (Pb), as cadmium nitrate and lead nitrate solutions, at 30 ppm concentrations, on the cell cycle of root-tip meristem cells in maize. Red light stimulated the mitotic activity of the meristemic cells of the maize root-tip meristem growth after irradiation of seed samples with simultaneous treatment in the presence of Cd or Pb. The mitotic index was inhibited when the seeds were treated with distilled water with the addition of Cd or Pb salts. Seeds treated with laser had significantly the highest mitotic index. Results revealed that maize seed pre-treatment with the red light protects the root-tip meristem cells against the mitodepressive effect of Cd and Pb ions. Seed biomodulation using red light emitted by He-Ne laser can positively effect the germination and plant growth.

The Effects of Green Tea Leaf Extract on Cytogenetical and Physiological Parameters of Allium cepa L. exposed to Salinity

The aim of this study investigated the effects of 50 mg L-1 green tea leaf extract in decreasing harmful effects of 0.175 M salinity stress on the mitotic activity, chromosomal aberrations, seedling growth (fresh weight, radicle length and radicle number), micronucleus frequency which is the simplest indicator, the most effective of cytological damage and bulb germination of A. cepa L. In only green tea leaf extract medium, the radicle length and radicle number of bulbs were partially reduced compared to the control bulbs germinated in the distilled water medium. While their germination percentage and fresh weight statistically indicated the same values. Besides, the mitotic index and chromosomal abnormalities in the root tip meristematic cells of Allium cepa bulbs germinated in alone green tea leaf extract medium increased compared to germinated control bulbs in the distilled water medium, whereas the micronucleus frequency showed statistically the same value compared to the control. In other words, it can be said that salt stress significantly inhibited the seedling growth and bulb germination of Allium cepa. What’s more, it significantly reduced the mitotic index in the root tip meristems of the bulbs and increased the number of chromosomal abnormalities and micronuclues frequency. On the other hand, inhibitory effects of salt on the mitotic activity, seedling growth, bulb germination, chromosomal abnormalities and micronuclues frequency significantly decreased with the application of green tea leaf extract. The germination percentage, radicle lenght, radicle number, fresh weight, mitotic index, micronuclues frequency and chromosomal aberrations of the seedlings grown in 0.175 M salinity were 23 %, 10.3 mm, 12.7, 7 g, 1.2 %, 13 % and 17 % respectively, while these values became 75 %, 13.4 mm, 17.2, 13.8 g, 6.3 %, 9 % and 9.3 % in the seedlings treated with 50 mg L-1 green tea leaf extract.

The Potential Risk Assessment of Phenoxyethanol with a Versatile Model System

In this study, the toxic effects of phenoxyethanol (Phy-Et), which is widely used in cosmetic industry, has been investigated with Allium test by means of physiological, cytogenetic, anatomical and biochemical parameters. To determine the changes in physiological reactions weight gain, relative injury rate, germination percentage and root length were investigated. Malondialdehyde, superoxide dismutase, glutathion and catalase levels were analyzed as biochemical parameters for determining the presence of oxidative stress. Mitotic index, micronucleus and chromosomal abnormality frequencies were studied as cytogenetic evaluation and the anatomical changes in root tip cells were investigated by cross sections. Changes in surface polarity and wettability were investigated by taking contact angle measurements of pressed root preparations. The mechanism of toxicity has been tried to be explained by these contact angles and this is the first study using contact angle measurements in toxicity tests. Consequently, exposure to Phy-Et resulted in a decrease in all measured physiological parameters and in mitotic index. In contrast, significant increases in the micronucleus and chromosomal abnormality frequencies were observed and the most significant toxic effect was found in 10 mM Phy-Et treated group. Phy-Et application induced oxidative damage and caused a significant increase in malondialdehyde level and a decrease in glutathione level compared to control group. Also a response occured against oxidative damage in superoxide dismutase and catalase activity and the activities increased in 2.5 mM and 5 mM Phy-Et treated groups and decreased in 10 mM Phy-Et treated groups. Furthermore, Phy-Et treatment resulted in some anatomical damages and changes such as necrosis, cell deformation and thickening of the cortex cell wall in root tip meristem cells of A. cepa. In the contact angle measurements taken against water, it was found that the wettability and hydrophilicity of the root preparations treated with Phy-Et were reduced, and this was the explanation of the growth abnormalities associated with water uptake. As a result, it was found that Phy-Et application caused toxic effects on many viability parameters and A. cepa test material was a reliable biomarker in determining these effects.

Cytogenetic and Physiologic Efficacies of Grape Seed Extract in Allium cepa L. Seeds Exposed to Salinity

In this study, effects of grape seed extract (GSE) on the seedling growth (fresh weight, radicle length, radicle number), seed germination, mitotic activity, chromosomal aberrations (CAs) and micronucleus frequency (MN) in Allium cepa L. seeds germinated in both saline and normal conditions investigated. In only GSE medium, althought the radicle number and radicle length of seeds partially reduced compared to the control seeds germinated in distilled water medium, the fresh weight partly ascended and germination percentage indicate statistically the same value as the control. Besides, whereas the mitotic index in root-tip meristems of A. cepa seeds germinated in alone GSE medium showed increase compared to the control seeds, CA and MN showed statistically the same values compared to the control. On the other hand, salt stress significantly inhibited the seedling growth and seed germination of A. cepa. What’s more, it reduced significantly the mitotic index in root-tip meristems of the seeds and escalated the number of CA and MN, which is the simplest indicator and the most effective of cytological damage. Contrariwise, inhibitive effects of salt on the mitotic activity, seedling growth, seed germination and CA significantly decreased with application of GSE but, GSE was inefficient in reducing of salt damage on MN.

Cytogenetical and Physiological Effects of β-alanine Treatment in Alleviation of Salt-Induced Stress in Allium cepa L.

In this study, β-alanine effects on the seedling growth (radicle number, radicle length and fresh weight), seed germination, chromosomal aberrations, mitotic activity and micronucleus frequency in Allium cepa L. germinated in both salt stress and normal conditions investigated. In only β-alanine medium, the fresh weight, radicle number and radicle length of the seeds partially reduced compared to the control seeds germinated in distilled water medium but the germination percentage indicate statistically the same value ​​as the control. Besides, while the micronucleus formation and mitotic index in root tip meristems of A. cepa seeds germinated in alone β-alanine medium showed the same values as the control seeds germinated in distilled water medium, the chromosomal abnormalities exhibited an increase compared to the control. On the other hand, salt stress significantly inhibited the seedling growth and seed germination of A. cepa. What’s more, it majorly reduced the mitotic index in meristem cells of the seeds and increased the number of chromosomal abnormalities and micronuclei formation, which is the simplest indicator and the most effective of cytological damage. Althought the harmful affects of saltness on the chromosomal aberrations, seed germination, seedling growth and mitotic activity alleviated in varying degrees by β-alanine treatment, this application was inefficient in damage reducing of salt on the micronucleus formation.

Protective effects of anthocyanin-rich bilberry (Vaccinium myrtillus L.) extract against copper(II) chloride toxicity.

In this study, the protective effects of 50 mg/L and 100 mg/L doses of anthocyanin-rich bilberry extracts (ABE) against the toxicity caused by 20 μM copper(II) chloride (CuCl2) on Allium cepa L. were investigated. Alterations in weight gain, germination percentage, and root elongation were evaluated as physiological parameters while micronucleus (MN), mitotic index (MI), and chromosomal abnormality (CA) frequency were studied as cytogenetic parameters. Oxidative stress indicators such as malondialdehyde (MDA) formation, superoxide dismutase (SOD) activity, and catalase (CAT) activity were analyzed and also damages in root tip meristem cells were determined by cross sections. As a result, it was found that the percentage of germination, weight gain, root length, and MI decreased and the frequency of MN and CAs increased with CuCl2 treatment. CuCl2 exposure caused a significant increase in SOD and CAT activities and MDA levels. A number of anatomical abnormalities and damages were detected in the cross sections of CuCl2-treated roots. On the other hand, ABE applications ameliorated notably all copper-induced damages in a dose-dependent manner. Therefore, the powerful protective potential of ABE against copper-induced toxicity was proven through an extensive study in a popular plant model.

Effects of L-lysine on cytogenetical and physiological parameters in Allium cepa L. under salt stress

The role of L-lysine (Lys) on some cytogenetic and physiological parameters in Allium cepa L. seeds exposed to salt was evaluated. NaCl stress on the other hand showed a significantly inhibitory effect on the seedling growth and seed germination of Allium cepa. Besides, it significantly reduced the mitotic index in the root tip meristems of seeds and increased micronuclei which are the most effective and simplest indicator of cytological damage and chromosomal abnormalities. However, the effects of salinity on chromosomal aberrations, seedling growth, seed germination and mitotic activity have decreased significantly with Lys application.

Effects of sodium hypochlorite on some physiological and cytogenetical parameters in Allium cepa L. exposed to salt stress

The effects of sodium hypochlorite (NaClO) on the seed germination, seedling growth (radicle length, radicle number and fresh weight), mitotic activity and chromosomal aberrations of Allium cepa L. germinated under salt stress were studied. Salt stress considerably inhibited the seed germination and seedling growth of A. cepa. Furthermore, it markedly reduced the mitotic index in root tip meristems of the seeds and increased the number of chromosomal aberrations. Whereas, the detrimental effects of salt on the seed germination, seedling growth, mitotic activitiy and chromosomal aberrations were dramatically alleviated in varying degrees by NaClO application.

An efficient fabrication of ZnO–carbon nanocomposites with enhanced photocatalytic activity and superior photostability

Synthesis of carbon nanoparticles (CNPs) and their composite with ZnO has proposed for the first time by combustion of camphor and chemical precipitation method. TEM image shows the surface of ZnO covered by tiny CNPs and acts as structure directing agent that transforms ZnO nanorods to uniform spherical ZnO. CNPs play a vital role to improve the photocatalytic activity and photostability of ZnO up to five runs due to impeding the photo-corrosion of ZnO. Enhance in the photocatalytic activity of ZnO–carbon nanocomposite could be attributed to the excellent dye adsorption capacity, direct photooxidation of dye and suppression of photoinduced electron–hole recombination. The presence of CNPs in nanocomposite served as the main role in accepting the photogenerated electrons due to electronic interaction between ZnO and CNPs. The cytotoxicity studies of meristematic root tip cells of Allium cepa reveals that photocatalytically degraded products were less toxic.

Rhizophagy Cycle: An Oxidative Process in Plants for Nutrient Extraction from Symbiotic Microbes.

In this paper, we describe a mechanism for the transfer of nutrients from symbiotic microbes (bacteria and fungi) to host plant roots that we term the ‘rhizophagy cycle.’ In the rhizophagy cycle, microbes alternate between a root intracellular endophytic phase and a free-living soil phase. Microbes acquire soil nutrients in the free-living soil phase; nutrients are extracted through exposure to host-produced reactive oxygen in the intracellular endophytic phase. We conducted experiments on several seed-vectored microbes in several host species. We found that initially the symbiotic microbes grow on the rhizoplane in the exudate zone adjacent the root meristem. Microbes enter root tip meristem cells—locating within the periplasmic spaces between cell wall and plasma membrane. In the periplasmic spaces of root cells, microbes convert to wall-less protoplast forms. As root cells mature, microbes continue to be subjected to reactive oxygen (superoxide) produced by NADPH oxidases (NOX) on the root cell plasma membranes. Reactive oxygen degrades some of the intracellular microbes, also likely inducing electrolyte leakage from microbes—effectively extracting nutrients from microbes. Surviving bacteria in root epidermal cells trigger root hair elongation and as hairs elongate bacteria exit at the hair tips, reforming cell walls and cell shapes as microbes emerge into the rhizosphere where they may obtain additional nutrients. Precisely what nutrients are transferred through rhizophagy or how important this process is for nutrient acquisition is still unknown.

Toxicity evaluation of waste effluent from cassava-processing factory in lagos state, nigeria using the <i>Allium cepa</i> assay

Mutagenic and genotoxic effects of cassava wastewater (CWW) were investigated by assay of Allium cepa root meristematic cells. The physicochemical parameters of the wastewater samples were also determined. In Allium root growth inhibition test, experimental onion bulbs were cultivated in various concentrations of the CWW and distilled water was used as a negative control. After 72 h, the root tips from the treated bulb were processed for cytological studies by orcein squash technique. The mean lengths of root bundles were obtained and effective concentration (EC) values calculated. The cytotoxic effects on the onion root tips showed strong growth retardation at high concentrations of the effluent with EC value of 5.67%. The mitotic index (MI) 50 rapidly decreased with increasing effluent concentration compared to control. There was significant increase in frequency of chromosome aberrations (stickiness, c-mitosis, vagrant, bridged fragment, binuclei, multipolar anaphase, attached chromosome and laggard chromosome) in root tip meristem cells of Allium cepa at all tested concentrations. At lower concentrations (0.005%), binuclei, (0.5%), vagrant chromosome and (1.0%), bridged fragment were the most common aberrations observed while at higher concentrations, (100 %), c-mitosis, vagrant and bridged fragment were the typical aberrations observed. The results indicate that the effluent samples collected were highly mutagenic. The results of physicochemical analysis revealed that the concentrations of some parameters (turbidity, chemical oxygen demand (COD), biological oxygen demand (BOD), conductivity, total dissolved solid (TDS), total suspended solid (TSS), sulphate, nitrate, phosphate and metals-copper, cobalt, chromium, iron, manganese, magnesium, nickel, cadmium, lead, sodium, potassium and calcium) were above the maximum permissible limit set by world health organization (WHO) and could partly be correlated with the toxicity of wastewater. The findings indicate that the substances contained in the cassava effluents may be toxic to living organisms and may pollute the environment if untreated. Keywords : Mutagenicity, genotoxicity, cassava wastewater, chromosomal aberration, mitotic index, cyanide, Allium cepa.