Sterol metabolism in wheat treated by N-substituted morpholines

Wheat caryopses were treated with racemic fenpropimorph. As shown previously in other plant species, 9(β,19-cyclopropyl sterols were found to accumulate markedly. A distinctive feature was a remarkable accumulation of 31 -norcyclobranol, a very rare sterol in nature. A⁸-sterols were also identified. The ratio A⁸-sterols: cyclopropyl sterols was shown to depend greatly on the configuration of the methyl substituent in position 2 of fenpropimorph. Whereas cyclopropyl sterols predominated in the case of seedlings treated with the (2S)-2-methyl enantiomer, A⁸-sterols were shown to be very abundant in plants treated with the (2R)-2-methyl enantiomer. A⁸-sterols were shown also to be more abundant in leaves than in roots. Experiments were conducted to find out whether the phytotoxic response of plants to fenpropimorph could be ascribed to its action on sterol biosynthesis. From the results obtained it appears that this is not the case and thus the phytotoxic effect is probably related to a cellular target other than sterol biosynthesis.