Pyroxasulfone resistance in Lolium rigidum is metabolism-based

In earlier work (Busi et al Weed Research 2012) in AHRI, Roberto Busi evolved pyroxasulfone resistance in L. rigidum (annual ryegrass) by repeated selection at low pyroxasulfone dose (thus far we have not documented pyroxasulfone resistance evolution in the field). In Canada, Mangin, Hall & Beckie documented pyroxasulfone cross-resistance in triallate selected Avena fatua (Can J Plant Sci 2016).

This study shows that the resistance mechanism endowing pyroxasulfone resistance in this Lolium rigidum population is enhanced rates of pyroxasulfone metabolism. This enhanced rate of pyroxasulfone metabolism is associated with over-expression of two glutathione transferases. Thus, the resistance mechanism in this L. rigidum population of enhanced rates of pyroxasulfone metabolism suggests GST-catalysed increased rates of glutathione conjugation. More work is required for definitive evidence of specific responsible GSTs.