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Limited information exists on the global economic impact of glyphosate-resistant (GR) weeds. The objective of this manuscript was to estimate the potential yield and economic loss from uncontrolled GR weeds in the major field crops grown in Ontario, Canada. The impact of GR weed interference on field crop yield was determined using an extensive database of field trials completed on commercial farms in southwestern Ontario between 2010 and 2021. Crop yield loss was estimated by expert opinion (weed scientists and Ontario government crop specialists) when research data were unavailable. This manuscript assumes that crop producers adjust their weed management programs to control GR weeds, which increases weed management costs but reduces crop yield loss from GR weed interference by 95%. GR volunteer corn, horseweed, waterhemp, giant ragweed, and common ragweed would cause an annual monetary loss of (in millions of Can$) $172, $104, $11, $3, and $0.3, respectively, for a total annual loss of $290 million if Ontario farmers did not adjust their weed management programs to control GR biotypes. The increased herbicide cost to control GR volunteer corn, horseweed, waterhemp, giant ragweed, and common ragweed in the major field crops in Ontario is estimated to be (in millions of Can$) $17, $9, $2, $0.1, and $0.02, respectively, for a total increase in herbicide expenditures of $28 million annually. Reduced GR weed interference with the adjusted weed management programs would reduce farm-gate monetary crop loss by 95% from $290 million to $15 million. This study estimates that GR weeds would reduce the farm-gate value of the major field crops produced in Ontario by Can$290 million annually if Ontario farmers did not adjust their weed management programs, but with increased herbicide costs of Can$28 million and reduced crop yield loss of 95% the actual annual monetary loss in Ontario is estimated to be Can$43 million annually.

Cultivation of lowbush blueberry (Vaccinium angustifolium Aiton), an important crop in the eastern part of North America, is unique, as it is carried out over the course of two consecutive growing seasons. Pest management, particularly weed management, is impacted by this biennial cultural practice. The choice of methods to control weeds is narrow, and such a system relies heavily on herbicides for weed management. Availability of unique herbicide active ingredients for weed management is limited, and available herbicides are used repeatedly, so the risk of developing resistance is acute. Hair fescue (Festuca filiformis Pourr.), a perennial grass weed, has evolved resistance to hexazinone, a photosystem II inhibitor frequently used in lowbush blueberry production. We show that substitution of phenylalanine to isoleucine at position 255 is responsible for a decreased sensitivity to hexazinone by a factor of 6.12. Early diagnosis of resistance based on the detection of the mutation will alert growers to use alternative control methods and thus help to increase the sustainability of the cropping system.

Frequent cultivation is often used to control weeds in crops such as lettuce. The efficacy of this technique on weed populations has been evaluated, but the effect on weed emergence and seedbanks is less documented. Studies in mineral soil indicate that soil disturbance can increase both weed emergence and seed persistence depending on where seeds are redistributed in the soil profile. Evaluations done in muck soil are scarce. This study evaluated the effect of two and four repetitive shallow (3.4 to 7.1 cm deep) cultivations on weed emergence and the weed seedbank in muck soil. Cultivation treatments (0, 2, and 4 cultivations using a inter-row rototiller) were done in lettuce plots from 2017 to 2019. Weed density was evaluated by species before each cultivation date and after crop harvest. Viable seedbanks were evaluated by collecting soil samples before and after each growing season and placing them in greenhouse flats. Statistical analyses were based on mixed models. Results showed that shallow cultivation modified the emergence patterns of weeds but did not reduce total emergence during the subsequent years or viable seedbanks. After two seasons without seed inputs, total emergence was reduced by 46.6% and the seedbank was reduced by 31.7% regardless of the cultivation treatment. However, the seedbank of the very abundant common purslane (Portulaca oleracea) remained high.

The full spectrum of herbicide resistance in a weed can vary according to the mechanistic basis and cannot be implied from the selective pressure. Common ragweed (Ambrosia artemisiifolia L.) is an important weed species of horticultural crops that has developed resistance to linuron based on either target site– or non–target site resistance mechanisms. The objective of the study is to characterize the cross-resistance to metribuzin of linuron-selected biotypes of A. artemisiifolia with target site– and non–target site resistance and determine its genetic basis. Crosses were made between two types of linuron-resistant biotype and a linuron-susceptible biotype, and the progeny were further backcrossed with susceptible plants to the third backcross (BC3) generation to determine their responses to both herbicides compared with parental lines. The target site–based linuron-resistant biotype was cross-resistant to metribuzin, and resistance to both herbicides was maintained at the same level in the BC3 line. In contrast, the linuron-selected biotype with a non–target site resistance mechanism was not cross-resistant to metribuzin. In addition, the BC3 lines deriving from the non–target site resistant parents had very low-level resistance. While the target site–resistance trait is maintained through multiple crosses, non–target site based resistance would be lost over time when selection is absent or insufficient to retain all genes involved in resistance as a complex trait. This would imply A. artemisiifolia biotypes with different mechanisms would need to be managed differently over time.

Palmer amaranth is one of the most economically important and widespread weeds of arable land in the United States. Although no populations are currently known to exist in Canada, its distribution has expanded northward such that it is present in many of the states bordering Canada and multiple pathways exist for its introduction. In this short communication, we report on the transport of viable Palmer amaranth seed on imported sweet potato slips. A reproductive pair of Palmer amaranth seedlings were identified from soil accompanying imported sweet potato slips in 2018. Identification was confirmed using species-specific single nucleotide polymorphisms.

The introgression of a transgene conferring glyphosate resistance from Brassica napus (rapeseed, canola) to Brassica rapa weeds (bird rape) was documented at a single location in 2007. In 2015, several cases of glyphosate resistant mustard were reported by growers in areas where rapeseed was seldom grown.Survey result indicated glyphosate resistant bird rape mustard is present in areas where glyphosate tolerant corn and soybean are often grown in rotation. Genetic analyses reveal that hybridization followed by introgression and progressive loss of chromosome is the likely mechanism for the horizontal gene transfer (HGT) of glyphosate resistance.Introgression of the glyphosate-resistance conferring transgene in the populations studied appears to have occurred several times, consistent with the ease for B. rapa to form hybrids with B. napus. The introduction of a transgene into a crop should therefore take into account the weediness of the species that share a common genome and their ability to form hybrids. We provide here such an example between B. napus and B. rapa, and potentially between B. napus and Raphanistrum raphanistrum. © 2022 Her Majesty the Queen in Right of Canada. Pest Management Science © 2022 Society of Chemical Industry. Reproduced with the permission of the Minister of Agriculture and Agri-Food Canada.

Photosystem II (PS II)-inhibitor herbicide resistance in Ontario waterhemp [Amaranthus tuberculatus (Moq.) Sauer] populations is conferred via target-site resistance (TSR) and non–target site resistance (NTSR) mechanisms. Metribuzin-resistant (MR) A. tuberculatus is due to TSR. Conversely, in other populations of PS II–inhibitor resistant A. tuberculatus, plants are resistant to atrazine but metribuzin sensitive (MS). The objective of this study was to determine the biologically effective dose of metribuzin applied preemergence and postemergence for the control of MS and MR A. tuberculatus. Ten field experiments were conducted in 2019 and 2020 to determine the effective doses of metribuzin for 50%, 80%, and 95% control of MS and MR A. tuberculatus. Metribuzin applied preemergence at the calculated doses of 133, 350, and 1,070 g ai ha−1 controlled MS A. tuberculatus 50%, 80%, and 95%, respectively, whereas the calculated doses of 7,868 and 17,533 g ai ha−1 controlled MR A. tuberculatus 50% and 80%, respectively, at 12 wk after application (WAA). Metribuzin applied postemergence at the calculated doses of 245 and 1,480 g ai ha−1 controlled MS A. tuberculatus 50% and 80%, respectively; the calculated dose for 50% MR A. tuberculatus control was greater than the highest dose (17,920 g ai ha−1) included in this study. Metribuzin at 560 and 1,120 g ha−1 and pyroxasulfone/flumioxazin (240 g ai ha−1) applied preemergence controlled MS A. tuberculatus 88%, 95%, and 98%, respectively, at 12 WAA, whereas the same treatments only controlled MR A. tuberculatus 0%, 4%, and 93%, respectively, at 12 WAA. Metribuzin at 560 and 1,120 g ha−1 and fomesafen (240 g ai ha−1) applied postemergence controlled MS A. tuberculatus 65%, 70%, and 78%, and MR A. tuberculatus 0%, 1%, and 49%, respectively, at 12 WAA. Based on these results, PS II–inhibitor resistant A. tuberculatus with NTSR (enhanced metabolism) is controlled with metribuzin applied preemergence and postemergence; in contrast, PS II–inhibitor resistant A. tuberculatus with TSR (glycine-264-serine altered target site) is not controlled with metribuzin.

BACKGROUND Poa annua is a pervasive grassy, self‐pollinating, weed that has evolved resistance to 10 different herbicide modes‐of‐action, third most of all weed species. We investigated constitutive overexpression of genes associated with non‐target site resistance (NTSR) in POAAN‐R3 and the response of those genes when treated with trifloxysulfuron despite the biotype having a known target site mutation in acetolactate synthase (ALS). RESULTS Despite having an ALS target site mutation, POAAN‐R3 still had a transcriptomic response to herbicide application that differed from a susceptible biotype. We observed differential expression of genes associated with transmembrane transport and oxidation–reduction activities, with differences being most pronounced prior to herbicide treatment. CONCLUSIONS In the P. annua biotype we studied with confirmed target site resistance to ALS inhibitors, we also observed constitutive expression of genes regulating transmembrane transport, as well as differential expression of genes associated with oxidative stress after treatment with trifloxysulfuron. This accumulation of mechanisms, in addition to the manifestation of target site resistance, could potentially increase the chance of survival when plants are challenged by different modes of action., In Poa annua with target‐site resistance to ALS inhibitors, we observed constitutive expression of genes regulating transmembrane‐transport, and differential expression of genes associated with oxidative stress after treatment with trifloxysulfuron. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Plant evolution has been a complex process involving hybridization and polyploidization making understanding the origin and evolution of a plant’s genome challenging even once a published genome is available. The oilseed crop, Camelina sativa (Brassicaceae), has a fully sequenced allohexaploid genome with 3 unknown ancestors. To better understand which extant species best represent the ancestral genomes that contributed to C. sativa’s formation, we sequenced and assembled chromosome level draft genomes for 4 diploid members of Camelina: C. neglecta C. hispida var. hispida, C. hispida var. grandiflora, and C. laxa using long and short read data scaffolded with proximity data. We then conducted phylogenetic analyses on regions of synteny and on genes described for Arabidopsis thaliana, from across each nuclear genome and the chloroplasts to examine evolutionary relationships within Camelina and Camelineae. We conclude that C. neglecta is closely related to C. sativa’s sub-genome 1 and that C. hispida var. hispida and C. hispida var. grandiflora are most closely related to C. sativa’s sub-genome 3. Further, the abundance and density of transposable elements, specifically Helitrons, suggest that the progenitor genome that contributed C. sativa’s sub-genome 3 maybe more similar to the genome of C. hispida var. hispida than that of C. hispida var. grandiflora. These diploid genomes show few structural differences when compared to C. sativa’s genome indicating little change to chromosome structure following allopolyploidization. This work also indicates that C. neglecta and C. hispida are important resources for understanding the genetics of C. sativa and potential resources for crop improvement.

This is the first record of protoporphyrinogen oxidase (PPO) inhibitor resistance in eastern Canada, and the second record of a glyphosate-resistant weed in Quebec. In 2016 and 2017, waterhemp seed was collected from 25 locations across Ontario and Quebec. All populations tested positive for imazethapyr resistance. Three-way resistance to imazethapyr, atrazine, and glyphosate was confirmed in 80% of the samples. Additionally, between 2015 and 2017, waterhemp seed was collected from 74 locations in Ontario or Quebec and resistance to lactofen was confirmed in 28% of the seed lots screened.

Herbicide resistance is selected for within a weed population through the recurrent use of an herbicide. Once the use of the herbicide is reduced or discontinued, the trait may persist in the population unless resistance endows a fitness penalty. Few studies have examined the long-term persistence of an herbicide resistance trait in a weed population once the selection pressure that led to its prevalence has been removed. The objective of this research was to re-survey the locations described by A.J.J. Smisek in her 1995 study of a paraquat resistant biotype of C. canadensis on the grounds of the Harrow Research and Development Centre. Results indicate that, ∼20 yr after paraquat use was significantly reduced, a glyphosate resistant biotype had replaced the paraquat resistant biotype at all but one of the original locations surveyed by Smisek. The sole location where the paraquat resistant biotype was observed was an old, un-treed orchard row currently managed by mowing. This location not only served as a refuge for the paraquat resistant biotype, ensuring its persistence in the face of strong selection for glyphosate resistance at all other locations, but it facilitated the co-occurrence of glyphosate and paraquat resistant biotypes. The observation of a multiple resistant biotype at this location alone, with resistance to both paraquat and glyphosate, suggests a role for refugia in the stacking of herbicide resistance traits. Given that this stacking occurred in the absence of either herbicide, we hypothesize that the multiple resistant biotype arose through pollen mediated gene flow among biotypes.

Erwinia amylovora and Pseudomonas syringae are bacterial phytopathogens responsible for considerable yield losses in commercial pome fruit production. The pathogens, if left untreated, can compromise tree health and economically impact entire commercial fruit productions. Historically, the choice of effective control methods has been limited. The use of antibiotics was proposed as an effective control method. The identification of these pathogens and screening for the presence of antibiotic resistance is paramount in the adoption and implementation of disease control methods. Molecular tests have been developed and accepted for identification and characterization of these disease-causing organisms. We improved existing molecular tests by developing methods that are equal or superior in robustness for identifying E. amylovora or P. syringae while being faster to execute. In addition, the real-time PCR-based detection method for E. amylovora provided complementary information on the susceptibility or resistance to streptomycin of individual isolates. Finally, we describe a methodology and results that compare the aggressiveness of the different bacterial isolates on four apple cultivars. We show that bacterial isolates exhibit different behaviors when brought into contact with various apple varieties and that the hierarchical clustering of symptom severity indicates a population structure, suggesting a genetic basis for host cultivar specificity.

Cover cropping is a soil conservation practice that may reduce the impacts of the economically important pathogen Pseudomonas syringae on crops including squash (Cucurbita pepo). To date, no studies have directly quantified the effect of rye cover crops on P. syringae populations, nor on the bacterial community of squash leaves. In this work, we tested the hypothesis that the protective effects of cover cropping on squash may be mediated by cover cropping effects on the plant’s microbiota that in turn protects against P. syringae. Using combined 16S sequencing and culture-based approaches, we showed that rye cover cropping protects squash against P. syringae, by decreasing pathogen population size on squash leaves and increasing fruit health and marketability at harvest. We also found evidence of a strong effect of rye cover crops on bacterial communities of the squash phyllosphere. Those findings were more striking early in the growing season. Finally, we identified numerous phyllosphere bacteria belonging to the genera Sphingomonas, Methylobacterium and Pseudomonas that were promoted by rye cover crops. Overall, our findings suggest cover cropping is effective for the sustainable management of P. syringae on squash and may provide a reservoir of potential microbial biocontrol agents colonizing the phyllosphere.

In this short communication, we report the observation of a tricotyledenous giant ragweed (Ambrosia trifida L.) individual. In contrast to the normal dicotyledenous pattern of phyllotaxy, this individual was observed to express three axillary meristems at each node that intersected the main stem at angles of 120°.

Common chickweed [Stellaria media(L.) Vill.] is an annual weed found in grain fields and pastures. This creeping weed produces a mat-like canopy that competes with crop seedlings for light and nutrients. This species is almost exclusively autogamous. Acetolactate synthase (ALS)-inhibiting herbicides are frequently used to control this broadleaf weed, and two mutations in theS. media ALSgene (Pro-197-Gln and Trp-574-Leu) have been reported to confer herbicide resistance. Seeds from several plants that survived an application of thifensulfuron-methyl/tribenuron-methyl (16 g ai ha−1) were collected from the same field in Québec, Canada. Seedlings were grown, tested for the presence of mutations in theALSgene, and treated with different rates of foramsulfuron, flumetsulam, and imazethapyr, each belonging to different families of ALS inhibitors. Two herbicide resistance–conferring mutations were identified in this population. One biotype had the previously reported Pro-197-Gln, while a new mutation, Pro-197-Ser, was identified in different plants from the same population. The new mutation (Pro-197-Ser) confers a lower level of resistance to sulfonylureas than Pro-197-Gln, and both biotypes are susceptible to imizadolinone and triazolopyrimidines.

The patient's response to the IVF stimulation protocol is highly variable and thus difficult to predict. When a cycle fails, there are often no apparent or obvious reasons to explain the failure. Having clues on what went wrong during stimulation could serve as a basis to improve and personalize the next stimulation protocol. This exploratory study aimed to investigate if it is possible to distinguish different failure causes or different follicular responses in a population of non-pregnant IVF patients. Using qRT-PCR, we analyzed a panel of genes indicative of different failure causes in patients who did not achieve pregnancy following an IVF cycle. Follicular cells samples from 135 women were analyzed. For each patient, a pool of follicular cells from all aspirated follicles was used as a sample which gives a global picture of the patient's ovary and not a specific picture of each follicle. We performed hierarchical clustering analysis to split the non-pregnant patients according to the gene expression pattern. The patient parameters and the gene expression levels were then compared between the groups resulting from the clustering. Hierarchical analysis showed that the population of non-pregnant IVF patients could be divided into three clusters. Gene expression was significantly different, and each cluster displayed a particular gene expression pattern. Follicular cells from patients in cluster 1 displayed a pattern of gene expression related to large incompetent follicles with a higher level of apoptosis (over matured). Gene expression in follicular cells from patients from cluster 2 was related to follicles not ready to ovulate (under mature); while follicular cells from patients in cluster 3 were characterized by an excess of inflammation with no visible symptoms. This study reinforces the idea that women often have different response to the same protocol and would benefit from more personalized treatments.

Glyphosate-resistant populations ofConyza canadensishave been spreading at a rapid rate in Ontario, Canada, since first being documented in 2010. Determining the genetic relationship among existing Ontario populations is necessary to understand the spread and selection of the resistant biotypes. The objectives of this study were to: (1) characterize the genetic variation ofC. canadensisaccessions from the province of Ontario using simple sequence repeat (SSR) markers and (2) investigate the molecular mechanism (s) conferring resistance in these accessions. Ninety-eightC. canadensisaccessions were genotyped using 8 SSR markers. Germinable accessions were challenged with glyphosate to determine their dose response, and the sequences of 5-enolpyruvylshikimate-3-phosphate synthase genes 1 and 2 were obtained. Results indicate that a majority of glyphosate-resistant accessions from Ontario possessed a proline to serine substitution at position 106, which has previously been reported to confer glyphosate resistance in other crop and weed species. Accessions possessing this substitution demonstrated notably higher levels of resistance than non–target site resistant (NTSR) accessions from within or outside the growing region and were observed to form a subpopulation genetically distinct from geographically proximate glyphosate-susceptible and NTSR accessions. Although it is unclear whether other non–target site resistance mechanisms are contributing to the levels of resistance observed in target-site resistant accessions, these results indicate that, at a minimum, selection for Pro-106-Ser has occurred in addition to selection for non–target site resistance and has significantly enhanced the levels of resistance to glyphosate inC. canadensisaccessions from Ontario.

Prodiamine is a dinitroaniline herbicide labeled for PRE control of goosegrass in warm- and cool-season turfgrass. In 2013, several golf course roughs in Maryville, TN reported poor goosegrass control (< 20%) following prodiamine treatment at 1,120 g ai ha-1. We harvested suspected prodiamine-resistant (PR) and prodiamine-susceptible (S) goosegrass phenotypes from the field and exposed them to a range of increasing prodiamine concentrations in hydroponic culture. Exposure to prodiamine at 0.001 mM reduced root growth of the S phenotype to 11% of the non-treated check. By comparison, exposure to 0.001 mM prodiamine had minimal effect on the PR phenotype, as root growth was 94% of the non-treated check. Molecular analyses revealed that PR plants contained a threonine (Thr) to isoleucine (Ile) substitution at position 239 on the α-tubulin 1 (TUA1) protein. The substitution, found in all PR plants, is the mechanism of prodiamine resistance in this phenotype. In field studies, topramezone controlled PR goosegrass 72% to 89% by 50 d after treatment (DAT) compared to only 22% to 23% for foramsulfuron. Topramezone treatment injured bermudagrass 34% to 60% from 7 to 14 DAT; however, injury was≤6% 28 DAT and 0% by the end of the study. Our results indicate that POST applications of topramezone can control dinitroaniline-resistant goosegrass. In addition, we established an easy-to-use genotyping assay to quickly screen goosegrass phenotypes for a target-site mutation (Thr-239-Ile) on TUA1 associated with resistance to dinitroaniline herbicides such as prodiamine. Future research should work to expand this assay for use with other weed species and herbicidal modes of action.

BACKGROUND The occurrence of herbicide-resistant weed biotypes is increasing and this report of an acetyl-CoA carboxylase (ACCase) inhibitor-resistant Digitaria sanguinalis L. Scop. from southwestern Ontario is another example. The identified weed escaped control in an onion and carrot rotation in which graminicides were used for several consecutive years. Our goal was to characterize the level and mechanism of resistance of the biotype. RESULTS The biotype was resistant to all five ACCase inhibitor herbicides tested. Gene-expression profiling was performed because none of the mutations known to confer resistance in the ACCase gene were detected. RNASeq and quantitative reverse-transcriptase PCR (qRT-PCR) results indicated that transcription of ACCase was 3.4–9.3 times higher in the resistant biotype than the susceptible biotype. ACCase gene copy number was determined by qPCR to be five to seven times higher in the resistant compared with the susceptible biotype. ACCase gene overexpression was directly related to the increase of the ACCase gene copy number. CONCLUSION Our results are consistent with the hypothesis that overexpression of the herbicide target gene ACCase confers resistance to the herbicide. This is the first reported case of target gene duplication conferring resistance to a herbicide other than glyphosate. © 2017 Society of Chemical Industry See related Article

Background Due to the accessibility of underlying technologies the 'Omics', in particular genomics, are becoming commonplace in several fields of research, including the study of agricultural pests. The weed community is starting to embrace these approaches; genome sequences have been made available in the past years, with several other sequencing projects underway, as promoted by the International Weed Genome Consortium. Chromosome-scale sequences are essential to fully exploit the power of genetics and genomics. Results We report such an assembly for Conyza canadensis, an important agricultural weed. Third-generation sequencing technology was used to create a genome assembly of 426 megabases, of which nine chromosome-scale scaffolds cover more than 98% of the entire assembled sequence. As this weed was the first to be identified with glyphosate resistance, and since we do not have a firm handle on the genetic mechanisms responsible for several herbicide resistances in the species, the genome sequence was annotated with genes known to be associated with herbicide resistance. A high number of ABC-type transporters, cytochrome P450 and glycosyltransferases (159, 352 and 181, respectively) were identified among the list of ab initio predicted genes. Conclusion As C. canadensis has a small genome that is syntenic with other Asteraceaes, has a short life cycle and is relatively easy to cross, it has the potential to become a model weed species and, with the chromosome-scale genome sequence, contribute to a paradigm shift in the way non-target site resistance is studied. © 2020 Her Majesty the Queen in Right of CanadaPest Management Science © 2020 Society of Chemical Industry.

Potato producers in the Atlantic Canadian provinces of New Brunswick (NB) and Prince Edward Island (PE) rely on the photosystem II-inhibiting herbicide metribuzin for weed management. Recently, potato producers in the region have reported unacceptable common lambsquarters control following an application of metribuzin. Tissue and seed samples were collected from escaped common lambsquarters populations from across the potato producing regions of NB and PE and screened for the Ser264Gly mutation in psbA. Overall, 46% of sampled populations possessed the Ser264Gly mutation across the region. Cross-resistance testing to atrazine, metribuzin and linuron confirmed populations with the Ser264Gly were resistant to triazines and triazinones but remained susceptible to linuron. Dose response analysis determined a moderate level of resistance to metribuzin in common lambsquarters which would not be controlled in producers fields. A field experiment was conducted in Fredericton, NB and Harrington, PE, to determine if currently registered and unregistered products and tank-mixes would control PSII-inhibitor-resistant common lambsquarters in potato. All evaluated products, with the exception of S-metolachlor, provided control equivalent to the weed-free check without compromising potato yield or quality. This study demonstrates that PSII-inhibitor-resistant common lambsquarters are found in Atlantic Canadian potato production systems, but can be controlled with currently registered herbicides and rates with alternative modes of action.

Common ragweed (Ambrosia artemisiifolia L.) is frequently observed in Quebec carrot fields. Carrot growers essentially rely on linuron, a photosystem II inhibitor, to control this broadleaf weed. A...

The occurrence of herbicide-resistant weed biotypes is increasing and this report of an acetyl-CoA carboxylase (ACCase) inhibitor-resistant Digitaria sanguinalis L. Scop. from southwestern Ontario is another example. The identified weed escaped control in an onion and carrot rotation in which graminicides were used for several consecutive years. Our goal was to characterize the level and mechanism of resistance of the biotype.The biotype was resistant to all five ACCase inhibitor herbicides tested. Gene-expression profiling was performed because none of the mutations known to confer resistance in the ACCase gene were detected. RNASeq and quantitative reverse-transcriptase PCR (qRT-PCR) results indicated that transcription of ACCase was 3.4-9.3 times higher in the resistant biotype than the susceptible biotype. ACCase gene copy number was determined by qPCR to be five to seven times higher in the resistant compared with the susceptible biotype. ACCase gene overexpression was directly related to the increase of the ACCase gene copy number.Our results are consistent with the hypothesis that overexpression of the herbicide target gene ACCase confers resistance to the herbicide. This is the first reported case of target gene duplication conferring resistance to a herbicide other than glyphosate. © 2017 Society of Chemical Industry See related Article.

The two forms of cytoplasmic male sterility (CMS) native to the oilseed rape or canola species Brassica napus, nap and pol, have novel features that may provide insight into the molecular mechanisms through which CMS/nuclear restorer systems evolve. One such feature is the finding that the distinct nuclear restorer genes for the two systems represent different alleles or haplotypes of the same nuclear locus. Improved understanding of how these systems have evolved will require molecular cloning and characterization of this novel locus. We have employed an approach that exploits the regional co-linearity between the Arabidopsis and Brassica genomes to construct a high-resolution genetic map of the nuclear restorer for the pol system, Rfp. Specifically, Arabidopsis-derived sequences have been used as a set of ordered RFLP probes to localize Rfp to a region of the B. napus genome equivalent to a 115 kb interval on Arabidopsis chromosome 1. Based on the known relationship of physical distances between orthologous segments of Arabidopsis and Brassica chromosomes, it is anticipated that the B. napus restorer locus is now mapped to sufficient resolution to permit its isolation and characterization.

We describe some instances in quantum information processing where numerical range techniques arise. We focus on two basic settings: higher-rank numerical ranges and their relevance in theoretical quantum error correction, and the classical numerical range and its use for comparing quantum information processing operations. We present the basic theory, discuss examples and formulate open problems.

Adenosine monophosphate-activated kinase (PRKA) is a serine/threonine kinase that functions as a metabolic switch in a number of physiological functions. The present study was undertaken to assess the role of this kinase in nuclear maturation of porcine oocytes. RT-PCR and immunoblotting revealed the expression of the PRKAA1 subunit in granulosa cells, cumulus-oocyte complexes (COC), and denuded oocytes (DO). Porcine COC and DO contained transcripts that corresponded to the expected sizes of the designed primers for PRKAB1 and PRKAG1. The PRKAA2 subunit was detected in granulosa cells and COC, whereas the PRKAG3 subunit was not detected in granulosa cells, COC or DO, whereas it was detected in the heart. The PRKAA1 protein was detected in granulosa cells, COC, DO, and zona pellucida (ZP). In the presence of the pharmacological activator of PRKA 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranosyl 5'-monophosphate (ZMP), COC were transiently maintained in meiotic arrest in a fully reversible manner. This inhibitory effect was not observed in DO. Other known PRKA activators, 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR) and metformin, also blocked meiotic resumption in COC. In contrast to mouse oocytes, in which PRKA activators reverse the inhibitory effect of PDE3 inhibitors, this combination still blocked meiotic resumption in porcine COC. These results demonstrate that the meiotic resumption of porcine COC is transiently blocked by PRKA activators in a dose-dependent manner, and that this effect is dependent on PRKA activity in cumulus cells. The present study describes a new role for PRKA in regulating meiotic resumption in COC and strongly suggests that cumulus cells play an essential role in the control of porcine oocyte maturation through the PRKA metabolic switch.

We consider the transmission properties of a novel type of optical filter, based on a periodic array of curved coupled optical waveguides in which the curvature varies periodically with propagation distance. For carefully chosen curvature profiles, this system exhibits transmission resonances that arise in direct analogy to the dynamic localization of electrons in a periodic potential in a periodic ac electric field. We demonstrate its use as a bandpass optical filter and show how the curvature profile can be adjusted to tailor the transmission of the structure.

The meiosis of mammalian oocytes begins during the fetal life and stops at the dictyate stage. This study has assessed the role of specific phosphodiesterase (PDE) inhibitors on the control of meiotic resumption in porcine oocytes investigating the influence of PMSG-hCG and cAMP stimulation. Cumulus-oocytes complexes (COCs) and denuded oocytes (DOs) were collected from gilt ovaries obtained at a local slaughterhouse. Oocytes were cultured in NCSU23 with different PDE inhibitors. The EC(50) for oocytes maintained in germinal vesicle (GV) stage was evaluated using different doses of both cilostamide (CIL), PDE3 inhibitor and 3-isobutyl-1-methylxanthine (IBMX), a nonspecific PDE inhibitor. In presence of PMSG-hCG, meiotic resumption is observed after 24 hr of culture. Both CIL and IBMX reversibly blocked meiotic resumption. In absence of PMSG-hCG, meiotic resumption is reduced after 24 hr of culture. After 48 hr of culture, only CIL significantly blocked meiotic resumption. Still in absence of PMSG-hCG, significant effect of treatment was only observed in COCs using the combination of CIL and rolipram (PDE3 and PDE4 inhibitor, respectively) compared to the use of IBMX. To assess the contribution of cAMP synthesis, a low dose of an adenylyl cyclase (AC) stimulator, forskolin, has been used in combination with CIL showing a significant effect of this combination. In CIL-treated COCs and DOs, significant higher percentages of oocytes were maintained in GV stage when cultured in combination with forskolin instead of PMSG-hCG. In conclusion, these results demonstrate that the control of meiotic resumption in porcine oocytes is highly regulated by cAMP. Both the degradation by specific PDE3 enzyme and the synthesis by an active AC are highly involved.

A single radish nuclear gene, Rfo, restores Ogura (ogu) cytoplasmic male sterility (CMS) in Brassica napus. A map-based cloning approach relying on synteny between radish and Arabidopsis was used to clone Rfo. A radish gene encoding a 687-amino-acid protein with a predicted mitochondrial targeting pre-sequence was found to confer male fertility upon transformation into ogu CMS B. napus. This gene, like the recently described Petunia Rf gene, codes for a pentatricopeptide repeat (PPR)-containing protein with multiple, in this case 16, PPR domains. Two similar genes that do not appear to function as Rfo flank this gene. Comparison of the Rfo region with the syntenic Arabidopsis region indicates that a PPR gene is not present at the Rfo-equivalent site in Arabidopsis, although a smaller and related PPR gene is found about 40 kb from this site. The implications of these findings for the evolution of restorer genes and other PPR encoding genes are discussed.

The serine/threonine kinase 5′ adenosine monophosphate-activated protein kinase (AMPK), a heterotrimeric protein known as a metabolic switch, is involved in oocyte nuclear maturation in mice, cattle, and swine. The present study analyzed AMPK activation in cumulus cell expansion during in vitro maturation (IVM) of porcine cumulus-oocyte complexes (COC). 5-Aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR) is a well-known activator of AMPK. It inhibited oocyte meiotic resumption in COC. Moreover, cumulus cell expansion did not occur in the presence of AICAR, demonstrating its marked impact on cumulus cells. Activation of AMPK was supported by AICAR-mediated phosphorylation of alpha AMPK subunits. Furthermore, the presence of AICAR increased glucose uptake, a classical response to activation of this metabolic switch in response to depleted cellular energy levels. Neither nuclear maturation nor cumulus expansion was reversed by glucosamine, an alternative substrate in hyaluronic acid synth...

The serine/threonine kinase 5' adenosine monophosphate-activated protein kinase (AMPK), a heterotrimeric protein known as a metabolic switch, is involved in oocyte nuclear maturation in mice, cattle, and swine. The present study analyzed AMPK activation in cumulus cell expansion during in vitro maturation (IVM) of porcine cumulus-oocyte complexes (COC). 5-Aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR) is a well-known activator of AMPK. It inhibited oocyte meiotic resumption in COC. Moreover, cumulus cell expansion did not occur in the presence of AICAR, demonstrating its marked impact on cumulus cells. Activation of AMPK was supported by AICAR-mediated phosphorylation of alpha AMPK subunits. Furthermore, the presence of AICAR increased glucose uptake, a classical response to activation of this metabolic switch in response to depleted cellular energy levels. Neither nuclear maturation nor cumulus expansion was reversed by glucosamine, an alternative substrate in hyaluronic acid synthesis, through the hexosamine biosynthetic pathway, which ruled out possible depletion of substrates. Both increased gap junction communication and phosphodiesterase activity in COC are dependent on protein synthesis during the initial hours of IVM; however, both were inhibited in the presence of AICAR, which supports the finding that activation of AMPK by AICAR mediated inhibition of protein synthesis. Moreover, this protein synthesis inhibition was equivalent to that of the well-known protein synthesis inhibitor cycloheximide, as observed on cumulus expansion and protein concentration. Finally, the phosphorylation level of selected kinases was investigated. The pattern of raptor phosphorylation is supportive of activation of AMPK-mediated inhibition of protein synthesis. In conclusion, AICAR-mediated AMPK activation in porcine COC inhibited cumulus cell expansion and protein synthesis. These results bring new considerations to the importance of this kinase in ovarian physiology and to the development of new oocyte culture medium.

Profilin is a ubiquitous actin-monomer-binding protein. The protistPhysarum polycephalum contains two profilins, ProA and ProP, present in amoebae and plasmodia, respectively. We have used mutantSaccharomyces cerevisiae cells in an attempt to observe distinct functions for the two profilins. Profilin-deficient yeast cells (Δpfy1) have delocalized actin cortical patches, do not contain visible actin cables, have reduced mating efficiency and do not grow at 37 °C or in the presence of caffeine. Deletion of theSRV2 gene (Δsrv2), coding for the adenylyl cyclase-associated protein, also results in an altered actin distribution and an inability to survive on rich medium. We found that the Δpfy1 and Δsrv2 mutant phenotypes were corrected equally well by the overexpression of Physarum ProA or yeast Pfy1p profilins. The Δpfy1 cells overexpressing ProP have improved mating efficiency and a normal distribution of actin cortical patches. These cells, however, have barely detectable actin cables, do not grow at 37 °C, and are sensitive to caffeine. Also, the expression of ProP does not correct the growth defect of the Δsrv2 cells. These results suggest that the two Physarum proteins are not functionally equivalent in yeast cells. No difference was detected in the affinity of ProA and ProP for poly-L-proline, while ProA has a slightly greater affinity than ProP for phosphatidylinositol 4,5-biphosphate.

Measurement of coupled quantum systems plays a central role in quantum information processing. We have realized independent single-shot read-out of two electron spins in a double quantum dot. The read-out method is all-electrical, cross-talk between the two measurements is negligible, and read-out fidelities are ~86% on average. This allows us to directly probe the anticorrelations between two spins prepared in a singlet state and to demonstrate the operation of the two-qubit exchange gate on a complete set of basis states. The results provide a possible route to the realization and efficient characterization of multiqubit quantum circuits based on single quantum dot spins.

In building a quantum-information processor (QIP), the challenge is to coherently control a large quantum system well enough to perform an arbitrary quantum algorithm and to be able to correct errors induced by decoherence. Nuclear magnetic resonance (NMR) QIPs offer an excellent testbed on which to develop and benchmark tools and techniques to control quantum systems. Two main issues to consider when designing control methods are accuracy and efficiency, for which two complementary approaches have been developed so far to control qubit registers with liquid-state NMR methods. The first applies optimal control theory to numerically optimize the control fields to implement unitary operations on low-dimensional systems with high fidelity. The second technique is based on the efficient optimization of a sequence of imperfect control elements so that implementation of a full quantum algorithm is possible while minimizing error accumulation. This paper summarizes our work in implementing both of these methods. Furthermore, we show that taken together, they form a basis to design quantum control methods for a block-architecture QIP so that large system size is not a barrier to implementing optimal control techniques.

We use NMR quantum simulators to study antiferromagnetic Ising spin chains undergoing quantum phase transitions. Taking advantage of the sensitivity of the systems near criticality, we detect the critical points of the transitions using a direct measurement of the Loschmidt echo. We test our simulators for spin chains of even and odd numbers of spins, and compare the experimental results to theoretical predictions.

A major goal of developing high-precision control of many-body quantum systems is to realise their potential as quantum computers. Probably the most significant obstacle in this direction is the problem of "decoherence": the extreme fragility of quantum systems to environmental noise and other control limitations. The theory of fault-tolerant quantum error correction has shown that quantum computation is possible even in the presence of decoherence provided that the noise affecting the quantum system satisfies certain well-defined theoretical conditions. However, existing methods for noise characterisation have become intractable already for the systems that are controlled in today's labs. In this paper we introduce a technique based on symmetrisation that enables direct experimental characterisation of key properties of the decoherence affecting a multi-body quantum system. Our method reduces the number of experiments required by existing methods from exponential to polynomial in the number of subsystems. We demonstrate the application of this technique to the optimisation of control over nuclear spins in the solid state., Comment: About 12 pages, 5 figures

We present an experimental implementation of the coined discrete time quantum walk on a square using a three qubit liquid state nuclear magnetic resonance (NMR) quantum information processor (QIP). Contrary to its classical counterpart, we observe complete interference after certain steps and a periodicity in the evolution. Complete state tomography has been performed for each of the eight steps making a full period. The results have extremely high fidelity with the expected states and show clearly the effects of quantum interference in the walk. We also show and discuss the importance of choosing a molecule with a natural Hamiltonian well suited to NMR QIP by implementing the same algorithm on a second molecule. Finally, we show experimentally that decoherence after each step makes the statistics of the quantum walk tend to that of the classical random walk., Comment: revtex4, 8 pages, 6 figures, submitted to PRA

Within the context of quantum teleportation, a proposed intuitive model to explain bipartite entanglement describes the scheme as being the same qubit of information evolving along and against the flow of time of an external observer. We investigate the physicality of such a model by applying the time-reversal of the Schrodinger equation in the teleportation context. To do so, we first lay down the theory of time-reversal applied to the circuit model and then show that the outcome of a teleportation-like circuit is consistent with the usual tensor product treatment, thus independent of the physical quantum system used to encode the information. Finally, we demonstrate a proof of principle experiment on a liquid state NMR quantum information processor. The experimental results are consistent with the interpretation that information can be seen as flowing backward in time through entanglement., Comment: 10 pages, 16 figures, changed the approach in the theory section. Rewrote some sections for clarity

Noise and imperfection of realistic devices are major obstacles for implementing quantum cryptography. In particular birefringence in optical fibers leads to decoherence of qubits encoded in polarization of photon. We show how to overcome this problem by doing single qubit quantum communication without a shared spatial reference frame and precise timing. Quantum information will be encoded in pair of photons using ``tag'' operations which corresponds to the time delay of one of the polarization modes. This method is robust against the phase instability of the interferometers despite the use of time-bins. Moreover synchronized clocks are not required in the ideal situation no photon loss case as they are only necessary to label the different encoded qubits., Comment: 4 pages, 2 figures

A single radish nuclear gene, Rfo, restores Ogura (ogu) cytoplasmic male sterility (CMS) in Brassica napus. A map-based cloning approach relying on synteny between radish and Arabidopsis was used to clone Rfo. A radish gene encoding a 687-amino-acid protein with a predicted mitochondrial targeting pre-sequence was found to confer male fertility upon transformation into ogu CMS B. napus. This gene, like the recently described Petunia Rf gene, codes for a pentatricopeptide repeat (PPR)-containing protein with multiple, in this case 16, PPR domains. Two similar genes that do not appear to function as Rfo flank this gene. Comparison of the Rfo region with the syntenic Arabidopsis region indicates that a PPR gene is not present at the Rfo-equivalent site in Arabidopsis, although a smaller and related PPR gene is found about 40 kb from this site. The implications of these findings for the evolution of restorer genes and other PPR encoding genes are discussed.

We give a convenient representation for any map that is covariant with respect to an irreducible representation of SU(2), and use this representation to analyze the evolution of a quantum directional reference frame when it is exploited as a resource for performing quantum operations. We introduce the moments of a quantum reference frame, which serve as a complete description of its properties as a frame, and investigate how many times a quantum directional reference frame represented by a spin-j system can be used to perform a certain quantum operation with a given probability of success. We provide a considerable generalization of previous results on the degradation of a reference frame, from which follows a classification of the dynamics of spin-j system under the repeated action of any covariant map with respect to SU(2)., 18 pages. Accepted in Journal of Mathematical Physics