Cytological, anatomical and biochemical studies on the side-effect of some pesticides

ABSTRACT

The invisible side-effects of triazophos and spinosad [insecticides], thiophanate-methyl [fungicide] and 2,4-D [herbicide] on plant were carried out using the bioassay test system of Vicia faba root tips to detect their cytotoxicity. Also, effects on the anatomical and biochemical characteristics were investigated. The obtained data showed that a linear decrease in mitotic index [MI] with increasing pesticide concentration. In addition, a linear correlation between the concentration and percentage of chromosomal abnormalities was recorded in the presently treated pesticides. The EC50 values caused undivided to 50% of total root tip cells were 3.61x10[-6], 1.31x10[-3], 4.85x10[-3] and 35.5 ppm for spinosad, thiophanate-methyl, 2,4-D and triazophos, respectively. The results also revealed that all tested pesticides found to decrease the growth of seedlings by 50 to 60% compared to the control. The normal tissues of stem and root similar to control were obtained in the case of insecticide spinosad and tested fungicide thiophanate-methyl while, malformation of the parenchyma cells and dialysis of the cell walls were observed in the case of herbicide 2,4-D. All tested pesticides significantly decreased the protein content in shoot and root except the herbicide 2,4-D in the case of shoot tissue. The insecticide spinosad increased the DNA content while, insecticide triazophos, fungicide thiophanate-methyl and herbicide 2,4-D reduced the DNA content of shoot and root tissues. It is clear that the effect of tested pesticides depends on pesticide type and plant tissue. In addition, the peroxidase enzyme was high sensitive to the tested pesticides. In similar, all of the tested pesticides shown to be highly esterase inhibitors in the case of shoot tissues. It was clear that there were 5 bands of protein pattern in control sample. The protein bands identical with 95.9 and 56.2 KDa were recorded in all treatment samples. In contrast, the protein band of 40.4 KDa was completely disappeared from the homogenates of all tested treatments, Peroxidase isozyme [58.9 KDa] was appeared in tested fungicide and herbicide treatments. While, the band [30.8 KDa] was disappeared in all treatments. Two major esterase isozymes corresponded to 68.3 and 27.8 KDa were presented. These isozymes were appeared in all pesticide treatments except in the case of spinosad. In general, according to the results of present study it can be stated that; the evaluation of pesticides hazardous effects depends on their side visible effects on the non-target organism did not enough. The invisible side-effect is very important in this response