Pyroxasulfone metabolism in resistant Lolium rigidum: is it all down to GST activity?

Resistance to the herbicide pyroxasulfone is slowly but steadily increasing in agricultural weeds.

The evolved resistance of one Lolium rigidum population has been attributed to conjugation of pyroxasulfone to reduced glutathione, mediated by glutathione transferase (GST) activity.

To determine if GST-based metabolism is a widespread mechanism of pyroxasulfone resistance in L. rigidum, a number of putative-resistant populations were screened for GST activity towards pyroxasulfone, presence of GSTF13-like isoforms (previously implicated in pyroxasulfone conjugation in this species), tissue glutathione concentrations, and response to inhibitors of GSTs and oxygenases.

Although there were no direct correlations between pyroxasulfone resistance levels and these individual parameters, a random forest analysis indicated that GST activity was of primary importance for L. rigidum resistance to this herbicide.

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