Scholarly record

CYTOGENETIC EFFECTS OF THE COMMERCIAL FUNGICIDE TOPAS 100EC ON MERISTEMATIC ROOT CELLS OF ALLIUM CEPA L.

Assist. Prof. Dr. Liliana MIRON, Prof. Dr. Georgeta BELENIUC, Assoc. Prof. Dr. Elena DOROFTEI

Abstract

The present investigation was done to assess cytomorphologic and cell cycle parameters as indicators of genotoxicity as it is a simpler method and could be suggested for rapid screening of the vast range of agrochemicals used all over the world. The excessive and indiscriminate use of agrochemicals is responsible for increasing the level of pollutants in the soil environment resulting in cellular and molecular damage to the plants. Topas 100EC is a widely employed foliar fungicide for horticultural applications. Allium cepa L. is a reliable model for the assessment of xenobiotic genotoxicity and cytotoxicity. We evaluated the effects of the Topas 100EC in cell cycle stages of the meristem root cells of Allium cepa. The roots of Allium cepa were treated with 0.5, 1 and 2% concentration of Topas 100EC for 6 and 24 h, and in mitotic preparation of their respective root, mitotic index, phase indices and the genotoxic markers viz. chromosomal aberrations and binucleate cells were observed and the data statistically analysed. Ten bulbs were used for each concentration, treatment period, and control group. The roots were coloured by the Feulgen method and the slides were prepared by applying squashing method and the samples were analysed under light microscope (Epifluorescent Microscope Fluo 2 with a Bel Photonics DV-1300 digital camera). A significant decrease in mitotic index and increase in abnormality percentage as compared to control was observed which increased with the treatment duration and the concentration of Topas fungicide. Chromosomal aberrations like stickiness, condensation of chromosomes, c- mitosis and delay in spindle formation are seen immediately after 6-hour treatments. The bridge, stickiness, vagrant chromosomes, fragments, c-anaphase and multipolarity chromosome aberrations were observed in anaphase-telophase cells. The total chromosome aberrations were more frequent with an increasing in the exposure time and the concentrations of tested fungicide. The method used are applicable for biological monitoring of environmental pollutants, in our study, it has revealed the cytogenotoxic behaviour of higher concentrations of Topas fungicide than the indicated ones in horticulture.

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