| a codon deletion confers resistance to herbicides inhibiting protoporphyrinogen oxidase. | herbicides that act by inhibiting protoporphyrinogen oxidase (ppo) are widely used to control weeds in a variety of crops. the first weed to evolve resistance to ppo-inhibiting herbicides was amaranthus tuberculatus, a problematic weed in the midwestern united states that previously had evolved multiple resistances to herbicides inhibiting two other target sites. evaluation of a ppo-inhibitor-resistant a. tuberculatus biotype revealed that resistance was a (incompletely) dominant trait conferred ... | 2006 | 16894159 |
| evolved glyphosate-resistant weeds around the world: lessons to be learnt. | glyphosate is the world's most important herbicide, with many uses that deliver effective and sustained control of a wide spectrum of unwanted (weedy) plant species. until recently there were relatively few reports of weedy plant species evolving resistance to glyphosate. since 1996, the advent and subsequent high adoption of transgenic glyphosate-resistant crops in the americas has meant unprecedented and often exclusive use of glyphosate for weed control over very large areas. consequently, in ... | 2008 | 18273881 |
| biochemical and structural consequences of a glycine deletion in the alpha-8 helix of protoporphyrinogen oxidase. | a rare gly210 deletion in protoporphyrinogen oxidase (ppo) was recently discovered in herbicide-resistant amaranthus tuberculatus. according to the published x-ray structure of nicotiana tabacum ppo, gly210 is adjacent to, not in, the ppo active site, so it is a matter of interest to determine why its deletion imparts resistance to herbicides. in our kinetic experiments, this deletion did not affect the affinity of protoporphyrinogen ix nor the fad content, but decreased the catalytic efficiency ... | 2010 | 20399914 |
| interspecific hybridization transfers a previously unknown glyphosate resistance mechanism in amaranthus species. | a previously unknown glyphosate resistance mechanism, amplification of the 5-enolpyruvyl shikimate-3-phosphate synthase gene, was recently reported in amaranthus palmeri. this evolved mechanism could introgress to other weedy amaranthus species through interspecific hybridization, representing an avenue for acquisition of a novel adaptive trait. the objective of this study was to evaluate the potential for this glyphosate resistance trait to transfer via pollen from a. palmeri to five other weed ... | 2012 | 25568027 |
| amplified fragment length polymorphism-based genetic relationships among weedy amaranthus species. | weedy amaranthus species frequently cause economically significant reductions in crop yields. accurate identification of amaranthus species is important for efficient weed control, but amaranthus species can interbreed, which might cause difficulty when identifying hybrid-derived specimens. to determine which of several economically important weedy amaranthus species are most genetically similar, and thus most likely to produce viable hybrids, we performed amplified fragment length polymorphism ... | 2006 | 15829725 |
| biochemical characterization of metabolism-based atrazine resistance in amaranthus tuberculatus and identification of an expressed gst associated with resistance. | rapid detoxification of atrazine in naturally tolerant crops such as maize (zea mays) and grain sorghum (sorghum bicolor) results from glutathione s-transferase (gst) activity. in previous research, two atrazine-resistant waterhemp (amaranthus tuberculatus) populations from illinois, u.s.a. (designated acr and mcr), displayed rapid formation of atrazine-glutathione (gsh) conjugates, implicating elevated rates of metabolism as the resistance mechanism. our main objective was to utilize protein pu ... | 2017 | 28218978 |
| physical mapping of amplified copies of the 5-enolpyruvylshikimate-3-phosphate synthase gene in glyphosate-resistant amaranthus tuberculatus. | recent and rapid evolution of resistance to glyphosate, the most widely used herbicides, in several weed species, including common waterhemp (amaranthus tuberculatus), poses a serious threat to sustained crop production. we report that glyphosate resistance in a tuberculatus was due to amplification of the 5-enolpyruvylshikimate-3-p synthase (epsps) gene, which encodes the molecular target of glyphosate. there was a positive correlation between epsps gene copies and its transcript expression. we ... | 2017 | 27956489 |
| a generalised individual-based algorithm for modelling the evolution of quantitative herbicide resistance in arable weed populations. | simulation models are useful tools for predicting and comparing the risk of herbicide resistance in weed populations under different management strategies. most existing models assume a monogenic mechanism governing herbicide resistance evolution. however, growing evidence suggests that herbicide resistance is often inherited in a polygenic or quantitative fashion. therefore, we constructed a generalised modelling framework to simulate the evolution of quantitative herbicide resistance in summer ... | 2017 | 27174645 |
| resistance to ppo-inhibiting herbicide in palmer amaranth from arkansas. | the widespread occurrence of als inhibitor- and glyphosate-resistant amaranthus palmeri has led to increasing use of protoporphyrinogen oxidase (ppo)-inhibiting herbicides in cotton and soybean. studies were conducted to confirm resistance to fomesafen (a ppo inhibitor), determine the resistance frequency, examine the resistance profile to other foliar-applied herbicides and investigate the resistance mechanism of resistant plants in a population collected in 2011 (ar11-law b) and its progenies ... | 2016 | 26817647 |
| do plant traits predict the competitive abilities of closely related species? | invasive species are a threat to every ecosystem. there is a strong incentive to predict which species will become invasive before they become too widespread and unmanageable. different approaches have been advocated to assess invasive species potential. these include examining plant functional traits, quantifying competitive ability and phylogenetic comparison. in this study, we conducted experiments based on the above approaches in a multi-year, temporally replicated, set of experiments to com ... | 2015 | 26722108 |
| measuring rates of herbicide metabolism in dicot weeds with an excised leaf assay. | in order to isolate and accurately determine rates of herbicide metabolism in an obligate-outcrossing dicot weed, waterhemp (amaranthus tuberculatus), we developed an excised leaf assay combined with a vegetative cloning strategy to normalize herbicide uptake and remove translocation as contributing factors in herbicide-resistant (r) and -sensitive (s) waterhemp populations. biokinetic analyses of organic pesticides in plants typically include the determination of uptake, translocation (delivery ... | 2015 | 26383604 |
| managing the evolution of herbicide resistance. | understanding and managing the evolutionary responses of pests and pathogens to control efforts is essential to human health and survival. herbicide-resistant (hr) weeds undermine agricultural sustainability, productivity and profitability, yet the epidemiology of resistance evolution - particularly at landscape scales - is poorly understood. we studied glyphosate resistance in a major agricultural weed, amaranthus tuberculatus (common waterhemp), using landscape, weed and management data from 1 ... | 2016 | 25809409 |
| population genetics and origin of the native north american agricultural weed waterhemp (amaranthus tuberculatus; amaranthaceae). | • | 2014 | 25091000 |
| characterization of glyphosate resistance in amaranthus tuberculatus populations. | the evolution of glyphosate-resistant weeds has recently increased dramatically. six suspected glyphosate-resistant amaranthus tuberculatus populations were studied to confirm resistance and determine the resistance mechanism. resistance was confirmed in greenhouse for all six populations with glyphosate resistance factors (r/s) between 5.2 and 7.5. no difference in glyphosate absorption or translocation was observed between resistant and susceptible individuals. no mutation at amino acid positi ... | 2014 | 24956036 |
| distinct detoxification mechanisms confer resistance to mesotrione and atrazine in a population of waterhemp. | previous research reported the first case of resistance to mesotrione and other 4-hydroxyphenylpyruvate dioxygenase (hppd) herbicides in a waterhemp (amaranthus tuberculatus) population designated mcr (for mclean county mesotrione- and atrazine-resistant). herein, experiments were conducted to determine if target site or nontarget site mechanisms confer mesotrione resistance in mcr. additionally, the basis for atrazine resistance was investigated in mcr and an atrazine-resistant but mesotrione-s ... | 2013 | 23872617 |
| resistance to hppd-inhibiting herbicides in a population of waterhemp (amaranthus tuberculatus) from illinois, united states. | a population of waterhemp in a seed maize production field in central illinois, united states, was not adequately controlled after post-emergence applications of herbicides that inhibit 4-hydroxyphenylpyruvate dioxygenase (hppd). | 2011 | 21308951 |
| herbicide resistances in amaranthus tuberculatus: a call for new options. | amaranthus tuberculatus is a major weed of crop fields in the midwestern united states. making this weed particularly problematic to manage is its demonstrated ability to evolve resistance to herbicides. herbicides to which a. tuberculatus has evolved resistance are photosystem ii inhibitors, acetolactate synthase inhibitors, protoporphyrinogen oxidase inhibitors, and glyphosate. many populations of a. tuberculatus contain more than one of these resistances, severely limiting the options for eff ... | 2011 | 21073196 |
| characterization of de novo transcriptome for waterhemp (amaranthus tuberculatus) using gs-flx 454 pyrosequencing and its application for studies of herbicide target-site genes. | waterhemp is a model for weed genomics research in part because it possesses many interesting biological characteristics, rapidly evolves resistance to herbicides and has a solid foundation of previous genetics work. to develop further the genomics resources for waterhemp, the transcriptome was sequenced using roche gs-flx 454 pyrosequencing technology. | 2010 | 20680963 |
| out of the swamp: unidirectional hybridization with weedy species may explain the prevalence of amaranthus tuberculatus as a weed. | *amaranthus tuberculatus represents one of the most dramatic cases of weed invasion documented in the midwestern usa. the species is infamous for evolving resistance to multiple herbicides, and predicting whether these resistances may be transferred to widespread weeds of the amaranthus hybridus aggregate is a matter of epidemiological concern. here, we explore the patterns of genetic exchange between amaranthus tuberculatus and a. hybridus in an effort to understand whether allele introgression ... | 2009 | 19659658 |
| weed species shifts in glyphosate-resistant crops. | the adoption of glyphosate-based crop production systems has been one of the most important revolutions in the history of agriculture. changes in weed communities owing to species that do not respond to current glyphosate-based management tactics are rapidly increasing. clearly, glyphosate-resistant crops (grcs) do not influence weeds any more than non-transgenic crops. for most crops, the trait itself is essentially benign in the environment. rather, the weed control tactics imposed by growers ... | 2008 | 18232055 |
| fertility, segregation at a herbicide-resistance locus, and genome structure in bc hybrids from two important weedy amaranthus species. | field studies have established high potential for hybridization between two important and often coexisting weedy species, amaranthus hybridus and amaranthus tuberculatus. prezygotic reproductive barriers between these species are believed to be limited to pollen competition and availability. a greenhouse study showed that a herbicide-resistance gene (als) from a. hybridus could be introgressed into an advanced a. tuberculatus background (bc2). however, evidence is lacking in support of such tran ... | 2005 | 16029473 |
| differential response of amaranthus tuberculatus (moq ex dc) jd sauer to glyphosate. | midwest usa farmers have reported inconsistent control of amaranthus tuberculatus (= rudis) (moq ex dc) jd sauer by glyphosate in glyphosate-resistant crops. the potential of selection for decreased a tuberculatus sensitivity to glyphosate was therefore investigated in a reportedly resistant everly, ia population (p0-ev). evaluation of six a tuberculatus populations from the midwest usa estimated a seedling baseline sensitivity of 2.15 mm glyphosate. based on these results, three generations of ... | 2005 | 15912567 |
| triazine resistance in amaranthus tuberculatus (moq) sauer that is not site-of-action mediated. | while surveying illinois amaranthus tuberculatus (moq) sauer (tall waterhemp) half-sib populations for herbicide response variability, several were observed to segregate for resistance to atrazine. studies were conducted on greenhouse-grown a tuberculatus plants to compare atrazine responses among populations that were segregating for resistance (segr), uniformly sensitive (unis) or uniformly resistant (unir). in chlorophyll fluorescence assays, leaves of plants from the segr and unis population ... | 2003 | 14561071 |