The content and spectral characteristics of cytochrome P450 (Cyt P450) induced by rac- and S-metolachlor extracted from shoots of etiolated maize and rice seedlings were studied. The effects of rac- and S-metolachlor on activities of CYP1A1-associated ethoxyresorufin O-deethylase (EROD) and CYP2E1-associated 4-nitrophenol hydroxylase (4-NPH) were also measured. The content of maize and rice microsomal Cyt P450 induced by rac-metolachlor was higher than that induced by S-metolachlor with p<0.05. When induced by rac- and S-metolachlor, the maize Cyt P450 content was, respectively, 3.02- and 2.48-fold that of the control, while the rice Cyt P450 content was 1.91- and 1.33-fold that of the control. The EROD and 4-NPH activities induced by S-metolachlor were higher than that of rac-metolachlor. The interaction of microsomal Cyt P450 with S-metolachlor was higher than that with rac-metolachlor, which may be one of the reasons why S-metolachlor is superior at killing weeds compared with rac-metolachlor. These results will help to develop a better understanding of the tolerance for and selectivity of rac- and S-metolachlor.

Enantioselectivity in effects of metolachlor on Cyt 450 enzyme systems in maize and rice

239th National Meeting (2010)

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