Prevalence, spatial structure and evolution of resistance to acetolactate-synthase (ALS) inhibitors and 2,4-D in the major weed Papaver rhoeas (L.) assessed using a massive, country-wide sampling.

BACKGROUND: Corn poppy (Papaver rhoeas) is the most damaging broadleaf weed in France. Massively parallel amplicon sequencing was used to investigate the prevalence, mode of evolution and spread of resistance-endowing ALS alleles in 422 populations randomly sampled throughout poppy's range in France. Bioassays were used to detect resistance to the synthetic auxin 2,4-D in 43 of these populations. RESULTS: A total of 21 100 plants were analysed and 24 mutant ALS alleles carrying an amino-acid substitution involved or potentially involved in resistance were identified. The vast majority (97.6%) of the substitutions occurred at codon Pro197, where all six possible single-nucleotide non-synonymous substitutions plus four double-nucleotide substitutions were identified. Changes observed in the enzymatic properties of the mutant ALS isoforms could not explain the differences in prevalence among the corresponding alleles. Sequence read analysis showed that mutant ALS alleles had multiple, independent evolutionary origins, and could have evolved several times independently within an area of a few kilometres. Finally, 2,4-D resistance was associated with mutant ALS alleles in individual plants in one third of the populations assayed. CONCLUSION: The intricate geographical mosaic of mutant ALS alleles observed is the likely result of the combination of huge population sizes, multiple independent mutation events and human-mediated spread of resistance. Our work highlights the ability of poppy populations and individual plants to accumulate different ALS alleles and as yet unknown mechanisms conferring resistance to synthetic auxins. This does not bode well for the continued use of chemical herbicides to control poppy. © 2023 Society of Chemical Industry.

Physiological Approach to the Use of the Natural Compound Quinate in the Control of Sensitive and Resistant Papaver rhoeas.

Quinate (1,3,4,5-tetrahydroxycyclohexanecarboxylate) is a compound synthesized in plants through a side-branch of the shikimate biosynthesis pathway, which is accumulated after glyphosate and acetolactate synthase inhibiting herbicides (ALS-inhibitors) and has phytotoxic potential. The objective of this study was to evaluate the phytotoxicity of quinate on several weed species. Among the species evaluated, Cynodon dactylon, Bromus diandrus, Lolium rigidum, Sinapis alba, and Papaver rhoeas, P. rhoeas was the most sensitive, and its growth was controlled with quinate concentrations above 100 mM at the phenological stage of 6-8 true leaves. A physiological study, including the shikimate pathway and the physiological markers of ALS-inhibitors (carbohydrates and amino acids), was performed in the sensitive and resistant plants treated with sulfonylureas or quinate. The typical physiological effects of ALS-inhibitors were detected in the sensitive population (free amino acid and carbohydrate accumulation) and not detected in the resistant population. The mode of action of quinate appeared to be related to general perturbations in their carbon/nitrogen metabolism rather than to specific changes in the shikimate pathway. These results suggest the possibility of using quinate in the weed control management of P. rhoeas.

Metabolomics of the alimurgic plants Taraxacum officinale, Papaver rhoeas and Urtica dioica by combined NMR and GC-MS analysis.

INTRODUCTION: The phytoalimurgic plants, common dandelion (Taraxacum officinale), corn poppy (Papaver rhoeas) and stinging nettle (Urtica dioica) are a source of nutraceuticals. OBJECTIVES: To apply a combined metabolomic fingerprinting approach by nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS) to common dandelion, corn poppy and stinging nettles to obtain simultaneous identification and quantitation of the major classes of organic compounds. METHODOLOGY: The whole plants collected in the Cilento National Park were dried and then extracted to obtain non-polar and polar organic extracts. GC-MS was used for non-polar extracts while 1 H-NMR spectroscopy was used for polar extracts. In both cases, simultaneous identification and quantification of the bioactive metabolites was obtained. RESULTS: Non-polar organic extracts of all plants were mainly composed of palmitic, stearic and oleic acids. The two pentacyclic triterpenols α- and ß-amyrin were detected in nettle extract. The analysis of polar organic extracts allowed to detect and quantify organic acids and sugars as main metabolites along with amino acids, caffeoyl derivatives, flavonoids, and nucleotides. In particular, corn poppy leaves contained a huge amount of glyceric acid (55.7% of the total extract). Stinging nettles, instead, exhibited a large amount of choline (19.5%). CONCLUSION: Metabolomic approach coupling GC-MS with NMR spectroscopy allowed to provide a detailed metabolite profile of three alimurgic plants, common dandelion, corn poppy and stinging nettle, from both a qualitative and quantitative point of view.

Occurrence, genetic control and evolution of non-target-site based resistance to herbicides inhibiting acetolactate synthase (ALS) in the dicot weed Papaver rhoeas.

Non-target-site resistance (NTSR) to herbicides is a major issue for the chemical control of weeds. Whilst predominant in grass weeds, NTSR remains largely uninvestigated in dicot weeds. We investigated the occurrence, inheritance and genetic control of NTSR to acetolactate synthase (ALS) inhibitors in Papaver rhoeas (corn poppy) using progenies from plants with potential NTSR to the imidazolinone herbicide imazamox. NTSR to imazamox was inherited from parents over two successive generations. NTSR to tritosulfuron (a sulfonylurea) was observed in F1 generations and inherited in F2 generations. NTSR to florasulam (a triazolopyrimidine) emerged in F2 generations. Our findings suggest NTSR was polygenic and gradually built-up by accumulation over generations of loci with moderate individual effects in single plants. We also demonstrated that ALS alleles conferring herbicide resistance can co-exist with NTSR loci in P. rhoeas plants. Previous research focussed on TSR in P. rhoeas, which most likely caused underestimation of NTSR significance in this species. This may also apply to other dicot species. From our data, resistance to ALS inhibitors in P. rhoeas appears complex, and involves well-known mutant ALS alleles and a set of unknown NTSR loci that confer resistance to ALS inhibitors from different chemical families.

Antioxidant, antimutagenic, and anticarcinogenic effects of Papaver rhoeas L. extract on Saccharomyces cerevisiae.

The aim of this work was to analyze the antioxidant and antimutagenic/anticarcinogenic capacity of Papaver rhoeas L. water extract against standard mutagen/carcinogen methyl methanesulfonate (MMS) and radiomimetic zeocin (Zeo) on a test system Saccharomyces cerevisiae. The following assays were used: 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, quantitative determination of superoxide anion (antireactive oxygen species [antiROS test]), DNA topology assay, D7ts1 test--for antimutagenic--and Ty1 transposition test--for anticarcinogenic effects. Strong pro-oxidative capacity of Zeo was shown to correlate with its well-expressed mutagenic and carcinogenic properties. The mutagenic and carcinogenic effects of MMS were also confirmed. Our data concerning the antioxidant activity of P. rhoeas L. extract revealed that concentration corresponding to IC(50) in the DPPH assay possessed the highest antioxidant activity in the antiROS biological assay. It was also observed that a concentration with 50% scavenging activity expressed the most pronounced antimutagenic properties decreasing Zeo-induced gene conversion twofold, reverse mutation fivefold, and total aberrations fourfold. The same concentration possessed well-expressed anticarcinogenic properties measured as reduction of MMS-induced Ty1 transposition rate fivefold and fourfold when Zeo was used as an inductor. Based on the well-expressed antioxidant, antimutagenic, and anticarcinogenic properties obtained in this work, the P. rhoeas L. extract could be recommended for further investigations and possible use as a food additive.