| Research Abstract |
Contamination of the environment and agricultural products with environmental endocrine disruptors is a serious global problem. These chemicals were found in the environment and agricultural products at nano-level concentrations, and are suspected of affecting ecosystems and human health. Therefore, it is requested to develop novel technologies to remove contamination by nano-level concentrations of environmental endocrine disruptors, since most conventional technologies are high cost, take a long time to obtain results, and do not work effectively to remove contamination of nano-level chemicals. Certain plant species are grounding and have deep roots. These plants absorb and accumulate nano-level concentrations of environmental chemicals from a wide area through their root systems. On the other hand, it was found that certain enzymatic systems including cytochrome P450 (P450 or CYP) monooxygenases recognize and metabolize lipophilic xenobiotics. We attempted to clone genes coding for
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enzymes which metabolize environmental endocrine disruptors and to evaluate them for phytoremediation.
(1) Tobacco CYP71A11 gene was induced by the treatment with 2,4-D, bromoxynil and others to produce the CYP71A11 enzyme, which catalyzed N-demethylation of the herbicide chlorotoluron. Thus, CYP71A11 enzyme seemed to be important for the herbicide selectivity and resistance. Also, we have identified bromoxynil-response cis element in the promoter region of the CYP71A11 gene.
(2) Rice CYP72A18 cDNA was cloned and expressed in yeast. Yeast microsomes containing CYP72A11 enzyme metabolized the herbicide pelargonic acid. Thus, CYP72A11 was found to catalyze ω-1 hydroxylation of the herbicide pelargonic acid.
(3) The Lolium biotype WLR2 showing multiple herbicide cross-resistance specifically expressed CYP71R4 gene. Then, CYP71R4 cDNA was cloned and expressed in yeast. Yeast microsomes containing CYP71R4 enzyme metabolized the herbicide chlorotoluron. Thus, CYP71R4 was found to be involved in herbicide cross-resistance. Less
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