Combined cytogenetic and ultrastructural effects of substituted urea herbicides and synthetic pyrethroid insecticide on the root meristem cells of Allium cepa (original) (raw)
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Genotoxic Effects of Herbicide Illoxan (Diclofop-Methyl) on Allium cepa L
Turkish Journal of Biology
The genotoxic potential of the commercial herbicide Illoxan (containing 284 g/L diclofop-methyl) was determined by using chromosome aberrations in Allium cepa root tip cells. The EC 50 value was determined as 150.00 mg/L using a root growth inhibition test and then the roots were treated with 37.50, 75.00, and 150.00 mg/L concentrations for 12, 24, and 48 h. The results indicated that Illoxan significantly increased the abnormal cell frequency at all concentrations and treatment periods when compared with their controls, and this increase was dose-dependent for the 24 and 48 h treatments. On the other hand, Illoxan significantly decreased the mitotic index (MI) in all treatments when compared with their controls. The decrease in the mitotic index was slightly dose-dependent for the 24 and 48 h treatments. Illoxan did not affect the percentage of mitotic stages. For the pretreated root tips, Illoxan (except 37.50 mg/L at 12 and 24 h) significantly increased the frequency of abnormal cells in a dose-dependent manner. This study indicates that Illoxan decreased the mitotic index and produced clastogenic and aneugenic types of abnormalities in Allium cepa root tip cells. The data obtained in this study showed that plant bioassays can be used as an important test battery to detect possible genotoxicity of chemicals.
Cytogenetic effects of different herbicides viz. Atrazine, Avenoxan, Diuron and Quizalofop-P-ethyl (QPE), were evaluated in the root tip meristem cells of Allium cepa. In the Allium root growth test, the effective concentration (EC 50) value was determined as approximately 0.5 ppm in the case of Atrazine and Avenoxan and 1.0 ppm in the case of Diuron and QPE herbicides with a control for each combination. Mitotic index decreased with increasing herbicide concentration at each exposure time. In anaphase-telophase cells, the total percentages of different chromosomal aberrations like stickiness, bridges, break(s), ring chromosomes, vagrant chromosomes, c-mitosis, delayed anaphase, laggard(s) and micronuclei at high concentration (1 ppm) were calculated as 31.85% (Atrazine), 29.94% (Avenoxan), 36.66% (Diuron) and 41.04% (QPE). The total number of chromosome aberrations increased as herbicide concentration increased. Micro-nucleated cells were observed at different stages of the cell cycle. The frequency of the micronucleus was markedly higher at 1 ppm than at other test concentrations.
Plants are direct recipients of agro – toxics and therefore important materials for assessing environmental chemicals for genotoxicity. The meristematic mitotic cells of Allium cepa is an efficient cytogenetic material for chromosome aberration assay on environmental pollutants. Onion root tips were grown on moistened filter paper in petri dish at room temperature. Germinated root tips were then exposed to three concentrations of each pesticide for 24 h. About 1 – 2 mm length of root tip was cut, fixed in cornoy’s fixative, hydrolyzed in warm 1 N HCL, stained with acetocarmine and squashed on glass slide. About 3000 cells were scored and classified into interphase and normal or aberrant division stage. Cytotoxicity was determined by comparing the mitotic index (MI) of treated cells with that of the negative control. The MI of cells treated with Dichlorophen and Dichlorovos at one or more concentration was half or less than that of control are said to be cytotoxic. Genotoxicity was m...
Cytotechnology, 2016
2,4-Dichlorophenoxyacetic acid (2,4-D) is a synthetic plant growth regulator that is highly toxic to most broad leaved plants and relatively nontoxic to monocotyledonous plants; is frequently used as weed killer. The study aimed to investigate cytogenetic effects of different concentrations of 2,4-D (0.67, 1.34, 2.01, 2.68, 3.35 and 4.02 mg/L) on Allium cepa bulblets' root tips treated for 24 and 48 h. The results showed six types of structural aberrations: C-mitosis, stickiness, laggards, bridges, fragments and multipolarity that varied numerically compared to control. It significantly affected mitotic index (MI) at 24 and 48 h treatment. In the Allium test, MI increased significantly at three lower concentrations (0.67, 1.34, 2.01 mg/L) after treatment with 2,4-D for 24 h and decreased significantly at higher concentration. Whereas, 2,4-D treatment for 48 h increased MI at all concentrations with significantly decreased MI at the highest concentration. The experiment was extended using comet test that did not reveal significant difference among treatments except for application of 4.02 mg/L 2,4-D for 48 h; where cell damages were verified by comet test. Rest of the concentrations for any duration of time were not damaging and toxic to cells. The results showed, visible mitodepressive action of 4.02 mg/L 2,4-D when treated for 48 h that had tendency to become toxic if the roots had been in touch with 2,4-D for a longer time.
Cytogenetic activities of a triazine herbicide in root tips of Allium cepa and Vicia faba
1983
The cytogenetic effects of various treatments with aventox SC, a triazine herbicide containing ~imazine and trietazine, were investigated in Allium cepa and Vicia faba. Actively growing root tips of both plants were treated with 3 concentrations of the herbicide for 3, 6 and 24 h. The 3-h treatments caused an increase in mitotic index (MI), but 24-h treatments markedly reduced the mitotic activity. All treatments caused an imbalance in the frequency of mitotic phases. Aventox SC produced a number of-mitotic abnormalities resulting from an action on the spindle apparatus. These were C-metaphase and C-anaphase configurations, lagging chromosomes and multipolar ~anapliases and telophases. This herbicide also induced chromosomal stickiness and chromosomal aberrations comprising bridges and breakage, which indicate an action on the chromosomes. These aberrations indicate a mutagenic potential of'the tested herbicide and point out the need for mutagenicity testing of agricultural chemicals.
Cytological effects of the herbicide racer “flurochloridone” on Allium cepa
Caryologia, 2003
The present investigation was carried out to study the cytological effects of the herbicide racer "flurochloridone" (3-chloro-4-(chloromethyl)-1-[3-(trifluoromethyl)= phenyl]-2-pyrrolidinone) on Allium cepa with respect to the cell response, mitotic index, mitotic abnormalities and chromosome aberrations. The roots of bulbs were treated with the following concentrations depending on the root growth inhibition test: 80 ppm (LD 50 ), 40 ppm (LD 50/2 ) and 20 ppm (LD 50/4 ). The results indicated that flurochloridone herbicide reduced the mitotic division in A. cepa as compared to their control groups. The reduction in mitotic activity was more significant when the concentration of the herbicide increased and the exposure time was prolonged. The treatment conducted with flurochloridone induced a significant percentage of abnormal mitosis. Seven types of abnormalities were recorded: C-metaphase, laggards, stickiness, bridges, fragments, multipolarity and poliploidy. Micronucleated cells were also observed at interphase. In additon, in pretreated root tips, chromosome breaks, fragments and sister union were detected.
The Nucleus, 2010
A wide number of chemicals from different sources are released into the environment, some of which upon metabolic activation are converted to mutagenic products. These chemicals might hence possess threat to public health. Genotoxic potential of three promutagenso-phenylenediamine (o-PDA), mphenylenediamine (m-PDA) and maleic hydrazide (MH) was evaluated using Allium cepa as the test system. Following treatment the genotoxic endpoints measured in the root tissue were mitotic index, cells with mitotic or chromosome aberration and micronuclei. DNA damage in root cells was evaluated by comet assay. EC 50 determined on the basis of root growth for o-PDA, m-PDA, MH were between 7-8 mg/l, 65-70 mg/l and 9-10 mg/l respectively. All the three agents induced genotoxicity significantly, that followed a dose response. While o-PDA and m-PDA did not induce DNA damage significantly, induction of DNA damage by MH was significant and dose dependent. The study identifies the genotoxic potential and re-establishes the fact that Allium cepa could ideally be used for evaluation of chromosome aberration and DNA damage.
Journal of Natural Sciences Research, 2014
Pesticides possess biological activity including genotoxic influence and can affect non target organisms. The cyto-and genotoxicological potency of wide-spec (Abamectin+Emaamectin benzoate) pesticide was screened using Allium cepa L. test. Onion roots were exposed for 24 h to ten concentrations (0, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1ml.L-1) of pesticide and 8 gm.L-1 of cyclophosphamide as positive control. Some microscopic endpoints as: mitotic indices and chromosomal aberration types were evaluated. The results showed obvious concentrationdependence. Mitotic index decreased from 21.77% (negative control) to 11.97% (dose of 1.00). Abnormal cell's frequency was considerably increased, too. Root growth retardation was significant due to different doses. Physiological and clastogenic types of chromosomal aberrations, as: lagging, fragments, granule, bridges, polyploidy, stickiness, and micronuclei chromosomes were observed in all corresponding concentrations. Data of this study showed that analyzed pesticide (commonly used in Iraqi agriculture) can potentially induce cytotoxic and genotoxic effects on crops and ultimately damage biota and human health.