Organic toxicants and plants

Organic xenobiotics absorbed by roots and leaves of higher plants are trans located by different physiological mechanisms. The following pathways of xe nobiotic detoxication have been observed in higher plants: conjugation with such endogenous compounds as peptides, sugars, amino acids, and organic ac ids; oxidative degradation and consequent oxidation of xenobiotics with the final participation of their carbon atoms in regular cell metabolism. The small parts of xenobiotics are excreted maintaining their original structur e and configuration. Enzymes catalyze oxidative degradation of xenobiotics from the initial hydroxylation to their deep oxidation. The wide intracellu lar distribution and inductive nature of oxidative enzymes lead to the high detoxication ability. With plant aging, transformation of the monooxygenas e system into peroxidase takes place. Once in the cells, xenobiotics are in corporated into different cell organelles. All xenobiotics examined are cha racterized by a negative effect on cell ultrastructure. The penetration of high doses of xenobiotics into plant cells leads to significant deviations from the norm and, in some cases, even to the complete cell destruction and plant death. (C) 2000 Academic Press.