Metabolism of herbicide

Root tips squashes were also used to examine the cross-resistance of the R biotype to other mitotic disrupters. Mudge gi al- (3) had previously shown that field applications of all of the dinitroaniline herbicides were ineffective in controlling the R biotype, and this was confirmed using root tip squashes as well (20). The phosphoric amide herbicide amiprophosmethyl also inhibits polymerization of tubulin into microtubules (21) and causes the same kinds of mitotic disruption as the dinitroaniline herbicides. The R biotype is also cross-resistant to this herbicide (20). Because the structure of amiprophosmethyl and trifluralin are quite different, it is likely that mechanisms of resistance based upon translocation and/or metabolism of herbicides is unlikely (but see 16 for an exception). 

In considering whether MFO-catalyzed metabolism of herbicides is associated with cross-resistance in Lolium rigidum we have taken, initially, an indirect approach. Growth experiments with wheat showed that the MFO inhibitors aminobenzotriazole (ABT) and PBO synergized chlortoluron when the herbicide and inhibitors were added as a soil drench (34). This synergism was presumed to be due to the inhibition of MFO-catalysed metabolism of chlortoluron (27-29). Significantly, Kemp and Caseley (2) have shown that cross-resistant Alopecurus are relatively more susceptible to chlortoluron in the presence of ABT and other... 

Figure L Pathways for the metabolism of herbicides in plant cells. Herbicides may need de-esterification mediated by esterases in the cell wall prior to transport into the cell. Once inside the cell, detoxification followed by conjugation and transport into the vacuole is the main pathway.

Metabolism of Herbicides in Transgenic Rice Plants Expressing CYPlAl and CYP2B6 Gene... 

These results indicate that exogienous CYP2B6 proteins enhanced the metabolism of herbicides in transgenic rice plants and had a high potential to metabolize chemical conqmunds in vivo in the xenobiotic pathway. 

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