Treatment with the herbicide glyphosate led to significantly increased activities of the enzyme gluiathione S‐transferase (GST, EC 2.5.1.18) in wheat (Triticum aestivum L. cv. Kadett and cv. Satu), pea (Pisum sativum L. ev. Debreceni Világoszöld) and in maize (Zea mays. L. Pioneer 3839 hybrid) tissues. GST activities in wheat seedlings (cv. Kadett) exposed to 960 μM glyphosate for 4 days were ca 6‐fold and 3‐fold higher in shoots and roots, respectively, than in the controls. Glyphosate increased the GST activity to a lesser extent in pea and maize than in wheat. In wheat seedlings (cv. Satu) exposed let 120 μM glyphosate gradual increases in the content of non‐protein thiols were observed. After 7 days exposure to glyphosate the thiol levels rose to about 360% and 220% of the controls in wheal shoots and roots, respectively. The elevation of thiol content in glyphosate‐treated plants was shown to be primarily due increases of glutathione level. These results suggest that the enhanced glutathione metabolism may have a role in the mode of action or degradation of this herbicide.
Summary:
The phytotoxicity of glyphosate(N‐(phosphonomethyl glycine) to seedlings of white mustard (Sinapis alba) cultivated indoors was studied. Yellowing and wrinkling of leaves was observed, necrotic spots appeared and the elongation of the seedlings was significantly reduced at doses 0–49 kg ai/ha and above. Only when sprayed at 4–97 kg ai/ha was the effect of glyphosate 100% lethal (5–7 days after spraying) At the highest concentration of herbicide a marked decrease in chlorophyll content was found but with 0–49 kg ai/ha the chlorophyll content was found to be higher than that in the leaves of control plants.
Two and fourteen days after spraying with glyphosate and the commercial product samples of leaf and stem were harvested for electron microscopy. Cellular defects in the leaves ranging from slight swelling to complete disruption of the chloroplasts were detected at the two highest herbicide doses 48 h after spraying. These defects were intensified with time und in addition other sub‐morphological changes occurred: decrease in starch grain content, an increase in the number of dictyosomes and mitochondria, disruption of tonoplasts and increase of plastoglobuli In the more central parts of stem segments the commercial product resulted in greater cellular effects than did glyphosate. It is suggested that the differences may be due to the surfactant.
Changes in chlorophyll, non‐protein thiol and glutathione (GSH) levels, and the activity of glutathione S‐transferase (GST) were investigated in cadmium(ll) and mercury(ll) cchloride treated leaf discs of mature pedunculate oak trees (Quercus robur). Both heavy metals caused decreases in chlorophyll content, but mercury was more toxic than cadmium. Cadmium treatments (30–250μiM) resulted in increasing non‐protein thiol levels after 3d, but GSH contents decreased. Mercury (1–20μM) led to a concentration‐dependent decline in both non‐protein thiol and GSH levels. GST activities were not modified significantly by cadmium, but mercury treatments caused a dose‐ and time‐dependent enzyme induction. Both the phytotoxic‐ and GST‐inducing effect of mercury could be prevented by the cysteine precursor L‐2‐oxo‐4‐thiazolidinecarboxylic acid.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.