Metribuzin resistance via enhanced metabolism in a multiple herbicide resistant Lolium rigidum population

Abstract

BACKGROUND: The photosystem II (PSII)-inhibiting herbicides are important for Australian farmers to control Lolium rigidum Gaud. and other weed species in trazine tolerant (TT)-canola fields. A L. rigidum population (R) collected from a TT-canola field from Western Australia showed multiple resistance to PSII, acetyl-coenzyme A carboxylase (ACCase) and acetolactate synthase (ALS) inhibitors. The mechanisms of multiple resistance in this R population were determined. RESULTS: The R population showed a low-level (about 3.0-fold) resistance to the PSII-inhibiting herbicides metribuzin and atrazine. Sequencing of the psbA gene revealed no differences between the R and susceptible (S) sequences. Furthermore, [ 14 C]metribuzin experiments found no significant difference in metribuzin foliar uptake and translocation between the R and S plants. However, [ 14 C]-metribuzin metabolism in R plants was 2.3-fold greater than in S plants. The cytochrome P450 monooxygenase inhibitor piperonyl butoxide (PBO) enhanced plant mortality response to metribuzin and atrazine in both R and S populations. In addition, multiple resistance to ALS and ACCase inhibitors are due to known resistance mutations in ALS and ACCase genes. CONCLUSION: The results demonstrate that enhanced metribuzin metabolism likely involving cytochrome P450 monooxygenase contributes to metribuzin resistance in Lolium rigidum. This is the first report of metabolic resistance to the PSII-inhibiting herbicide metribuzin in Australian Lolium rigidum.

Mechanistic basis for synergism of 2,4-D amine and metribuzin in <i>Avena sterilis</i>

“…A similar HPLC protocol was used for metribuzin metabolism studies in the metribuzin-resistant crop lupin 27) and weed species of Raphanus raphanistrum 27) and L. rigidum. 42) Although it is not possible to draw a clear conclusion due to the lack of peak identifications, the results in this paper showed an increase in polar metabolites (Fig. 3), similar to the HPLC profile in the resistant species studied (e.g., major polar metabolites eluted during 10-15 min).…”

Non‐target‐site resistance mechanism of barnyardgrass [Echinochloa crus‐galli (L.) P. Beauv.] to florpyrauxifen‐benzyl

“…However, the total FPB metabolism difference between Sus and R barnyardgrass observed in the present study was too small to infer the FPB resistance mechanism. In addition, other previous studies for resistance mechanisms of 2,4‐D, imazamox, glufosinate, and metribuzin have revealed that enhanced metabolism is commonly found in resistant weeds 25–28 . Thus, to elucidate the relationship between FPB resistance and metabolism, it was necessary to investigate what types of metabolites were produced in Sus and R barnyardgrass at each sampling time and how they were involved in the FPB sensitivity/resistance mechanisms.…”

Biologically effective dose of metribuzin applied preemergence and postemergence for the control of waterhemp (Amaranthus tuberculatus) with different mechanisms of resistance to photosystem II–inhibiting herbicides

“…Evans et al (2017) found that a single GST enzyme, AtuGSTF2, correlated strongly with PS II resistance in A. tuberculatus. In other weed species, NTSR has been found to confer PS II-inhibitor resistance by P450 monooxygenase, which was recently reported to confer metribuzin resistance in rigid ryegrass (Lolium rigidum Gaudin) in Australia (Ma et al 2020). Amaranthus tuberculatus with PS II resistance due to NTSR is resistant to atrazine but sensitive to metribuzin (Patzoldt et al 2003;Vennapusa et al 2018).…”