Chromosomal aberrations and micronuclei induced in onion (Allium cepa) by gamma-radiation

The use of the aquatic plant Elodea canadensis to assess the effects of low-dose gamma irradiation

Responses of cytogenetic and growth endpoints of the aquatic plant Elodea canadensis were studied using the plants collected from non-contaminated control areas of the Yenisei River and exposed to external γ-radiation for 11-13 days in the laboratory. Elodea canadensis was exposed to 0.5-25 mGy/day γ-radiation dose rates from a ¹³⁷Cs source. The total number of aberrant cells and total root length were more sensitive elodea endpoints to γ-radiation than total shoot length and mitotic index of elodea. Radiation sensitivity of elodea can be compared with the sensitivity of such a Reference Plant as Wild Grass (1-10 mGy/day) recommended by the ICRP. Thus, the aquatic plant Elodea canadensis can be used as a radiation bioindicator.

Cytogenetic effects of β-particles in Allium cepa cells used as a biological indicator for radiation damages

Analysis of cytogenetics effects of ionizing radiation for flora and fauna is essential to determine the impact on these communities and may produce an efficient warning system to avoid harm to human health. Onion (Allium cepa) is a well-established in vivo standard model, and it is widely used in cytogenetics studies for different environmental pollutants. In this work, onion roots were exposed to 0.04-1.44 Gy of β-particles from a ⁹⁰Sr/⁹⁰Y source. We investigated the capacity of brief external exposures to β-particles on inducing cytogenetic damages in root meristematic cells of onion aiming to verify if onion can be used as a radiation-sensitive cytogenetic bioindicator. A nonlinear increase in the frequencies of chromosomal aberrations and cells with micronuclei was observed. Onion roots exposed to doses 0.13 Gy or higher of β-particles showed a significant difference (p<0.05) in these frequencies when compared to the unirradiated group. The frequencies of these endpoints showed to be suitable to assess the difference in the dose of beta radiation received from 0.36 Gy. Our research shows the potential of using cytogenetic effects in Allium cepa cells as a biological indicator for a first screening of genotoxic damages induced by brief external exposures to β-particles.

Lycopene: an antioxidant product reducing dithane toxicity in Allium cepa L

The current study was undertaken to assess the attenuating potential of lycopene against Dithane toxicity in Allium cepa L. roots. A. cepa bulbs were arranged in 6 groups. The control group was treated with tap water while the other groups were treated with 215 mg/L lycopene, 430 mg/L lycopene, 500 mg/L Dithane, 500 mg/L Dithane + 215 mg/L lycopene and 500 mg/L Dithane + 430 mg/L lycopene, respectively. When the treatments were completed, growth inhibition, biochemical, genotoxicity and meristematic cell injury analyses were performed. Lycopene did not cause any toxic effect when applied alone. While rooting percentage, root elongation, weight gain and mitotic index (MI) decreased in response to Dithane exposure, the frequency of micronucleus (MN) and chromosomal abnormalities (CAs) in addition to malondialdehyde (MDA) level and the catalytic activities of superoxide dismutase (SOD) and catalase (CAT) increased. Dithane promoted fragment, sticky chromosome, vagrant chromosome, unequal distribution of chromatin, bridge, nucleus bud and reverse polarization formation in meristem cells. Dithane also provoked meristematic cell injuries, including indistinct appearance of vascular tissue, epidermis cell damage and flattened cell nucleus. Lycopene mitigated all damage types, depending on the lycopene dose applied with Dithane. Hence, the data analysis revealed that lycopene provides exceptional antioxidant protection against the fungicide Dithane, which has devastating toxic potential.

Acute multiple toxic effects of Trifloxystrobin fungicide on Allium cepa L

Trifloxystrobin (TFS) is a strobilurin-type fungicide that should be investigated due to its risks to non-targeted organisms. The goal of this study was to assess the susceptibility of Allium cepa L. to TFS in a multi-pronged approach. For 72 h, 0.2 g/L, 0.4 g/L and 0.8 g/L doses of TFS were administered to A. cepa bulbs and the control group was treated with tap water. The toxic effects of TFS were tested, considering physiological, cytogenetic, biochemical and anatomical analyses. TFS delayed growth by reducing the rooting ratio, root elongation and weight increase. Following TFS treatments, mitotic index (MI) scores decreased, while the formation of micronucleus (MN) and chromosomal aberrations (CAs) ascended. CAs types induced by TFS were listed according to their frequency as fragment, vagrant chromosome, sticky chromosome, uneven distribution of chromatin, bridge, nucleus with vacuoles, reverse polarization and irregular mitosis. TFS provoked an increment in superoxide dismutase (SOD) and catalase (CAT) enzyme activities as well as an accumulation of malondialdehyde (MDA). Meristematic cells of A. cepa roots treated with TFS had various anatomical damages, including damaged epidermis, flattened cell nucleus, damaged cortex and thickness in the cortex cell wall. All damages arising from TFS treatments exhibited dose-dependency. The findings of the present study revealed the serious toxicity of TFS in a non-targeted plant. It should not be neglected to evaluate the potential hazards of TFS with different toxicity tests.

Effect of Gamma Radiation on Cytogenetic and Growth Endpoints of Allium cepa Seedlings in Long-Term Experiments

The effect of γ-radiation on the growth and cytogenetic endpoints of Allium cepa L. seedlings in a long period after irradiation in absorbed doses from 1.0 to 10.7 Gy were examined. The chromosome aberration rate was most sensitive to the radiation: it increased immediately after exposure at all doses. In the recovery period (up to 216 h) after irradiation, the chromosome aberration frequency naturally decreased but at the end of experiment in maximum doses remained above the control values. The impact of the initial level of chromosome aberrations on the inhibition of onion roots growth in the long terms after irradiation is discussed.

The long-term effects of γ-radiation on the growth of Allium cepa plants

PURPOSE

The purpose of this study was to assess the long-term effects of gamma-radiation, including low-dose radiation, on growth parameters of onion (Allium cepa) seedling roots 6-10 days after irradiation.

MATERIALS AND METHODS

Onion seedlings were exposed to a ¹³⁷Cs gamma source at doses ranging from 0.1 to 10 grays (Gy). Responses of root and shoot length growth were studied 6 and 10 days after irradiation.

RESULTS

Our results showed inhibition of the root and shoot length growth 6 days after exposure at all doses, including the low dose - 0.1 Gy. At a later point in time (day 10), root and shoot inhibition was only observed after irradiation at high doses (above 5 Gy), and that suggested the occurrence of cell repair after irradiation at low doses. The results indicated that the length of seedling roots was more sensitive to gamma-irradiation than the shoot length.

CONCLUSION

The results of the study suggested that short-term gamma-irradiation of onion seedlings (absorbed doses of 0.1-10 Gy) caused inhibition of plant growth 6 and 10 days after irradiation. The dose dependence of the onion root length was linear. The present study showed for the first time that short-term low-dose gamma-irradiation could induce long-term negative effects on plant growth.

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.