Metolachlor in corn (Zea mays) and soybean (Glycine max): persistence and biochemical signs of stress during its detoxification
1992
Scarponi, L. | Alla, M.N. | Martinetti, L.
Metolachlor translocation and persistence were investigated in corn (Zea mays L.) and soybean (Glycine max L.) during a 12-day period after treatment. Herbicide uptake was rapid, and its detoxification resulted in small residues of the parent molecule in soybean and negligible residues in corn by the 12th day. The accumulation of metolachlor in the roots and in the shoots was found to be greater in soybean than in corn seedlings. This seems to be due to a faster detoxification in corn than in soybean tissues because of the higher herbicide-induced activity of glutathione S-transferase (GST, EC 2.5.1.18) in the corn than in the soybean. A reduction of dry matter, protein, and chlorophyll content in the treated seedlings was observed. A decrease in chlorophyll appeared to be a consequence of reduced activity of 3-aminolevulinate dehydratase (ALA-D, EC 4.2.1.24). The increased activities in the treated seedlings of phenylalanine ammonia-lyase (PAL, EC 4.3.1.5), and of tyrosine ammonia-lyase (TAL, EC 4.3.1), key enzymes in phytoalexin biogenesis, confirmed the metolachlor-induced stress status.
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