Metazachlor effect on poplar - Pioneer plant species for riparian buffers.

Metazachlor belongs to one of the most used herbicides throughout the world. In order to prevent the contamination of water bodies by such herbicides, the riparian buffers are constructed. The selection of appropriate plant species for this purpose is necessary. In our project, we studied the possibility of grey poplar to uptake and biotransform metazachlor, along with the phytotoxic effect of metazachlor and its metabolites. We used two different models - suspension cultures and poplar regenerants cultivated in vitro. Our results show that the herbicide metazachlor is readily metabolized by both suspension cultures and regenerants to 16 detectable metabolites. The detailed scheme of biotransformation pathway in poplar tissue is presented for the first time. The profile of detected metabolites was approximately the same in poplar cell cultures and regenerants, but the ratio and amounts of particular compounds was significantly different. Generally, the highest concentration (peak area/mg of DW) of all metabolites was present in the roots; the only exception was lactate conjugate (deCl-MZCl-Lact), which accumulated in the cultivation media. Although the plants were not visibly affected by metazachlor or its metabolites, they showed changes in activity of antioxidant enzymes and increased content of phenolic substances, the indicators of stress.