Most Australian crop farm populations of the grass weed Lolium rigidum are multiple herbicide-resistant. Most resistant populations exhibit target site mutations (e.g. ACCase, ALS), as well as metabolic resistance due to cytochrome P450, catalysed enhanced rates of herbicide metabolism.
Interestingly, for the PS2 herbicides, target site mutations (psbA gene) are rare in these multiple resistant Lolium populations. Previously, we have documented metabolic resistance endowing resistance to PS2 triazine and urea herbicides. In this paper, paper Ma et al show that resistance to the triazinone herbicide metribuzin in a multiple resistant population is again not target site based but rather, it is metabolic resistance. Resistance is endowed by enhanced rates of metribuzin metabolism, likely P450 catalysed.
The first author of this paper, Dr Hongju Ma from Huazhong Agricultural University, Wuhan, was in AHRI for one year, sponsored by the China Scholarship Council.
Authors: Hongju Ma, Huan Lu, Heping Han, Qin Yu and Stephen Powles