Acetolactate synthase Ser-653-Asn mutation in redroot pigweed ( <i>Amaranthus retroflexus</i> ) gene confers high resistance to imidazolinones
Bibliographic record
Abstract
Abstract In the summer of 2016, a case of potentially herbicide-resistant redroot pigweed ( Amaranthus retroflexus L.) was reported in Saint-Louis-de-Gonzague (QC, Canada) in an identity-preserved soybean [ Glycine max (L.) Merr.] field where imazethapyr and chlorimuron-ethyl were applied preemergence, two active ingredients that inhibit acetolactate synthase (ALS). A few years earlier, several A. retroflexus populations resistant to ALS-inhibiting herbicides were reported in Manitoba (MB). Amaranthus retroflexus samples from these fields were collected and analyzed to characterize the presence of a resistance mechanism and the associated level of resistance. Sequencing of the ALS gene revealed a mutation resulting in a serine to asparagine substitution at amino acid position 653. Dose–response experiments indicated resistance factors of 27.7 to 194.0 to imazethapyr (imidazolinones) among these populations, but susceptibility to members of all other ALS inhibitor families that were tested. In one MB population, a serine to isoleucine substitution at position 653 was observed for the first time in A. retroflexus in some of the plants, and this contributed to the detection of resistance to thifensulfuron-methyl when compared with most susceptible control population. The response of the two MB control populations to thifensulfuron-methyl differed, and resistance factors were influenced by the level of susceptibility of the control populations to thifensulfuron-methyl. The same was not observed with imazethapyr. Non–target site resistance (NTSR) was not detected in the MB populations when they were exposed to malathion before exposure to the herbicide. We identified two new mutations on the ALS gene in A. retroflexus that result in ALS inhibitor–specific cross-resistance patterns. Further investigation into NTSR and the mechanism behind the differential response of the control populations to thifensulfuron-methyl are warranted.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".