scholarly journals Coevolution of resistance to PPO inhibitors in waterhemp (Amaranthus tuberculatus) and Palmer amaranth (Amaranthus palmeri)

Weed Science ◽  
2019 ◽  
Vol 67 (05) ◽  
pp. 521-526 ◽  
Author(s):  
Kathryn J. Lillie ◽  
Darci A. Giacomini ◽  
Jonathan D. Green ◽  
Patrick J. Tranel
Keyword(s):  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Pcr Assay ◽  
Common Waterhemp ◽  
First Case ◽  
Amaranthus Tuberculatus ◽  
Single Field ◽  
Inhibitor Resistance ◽  
Amino Acid Glycine ◽  
Quantitative Pcr Assay

AbstractThe first case of evolved protoporphyrinogen oxidase (PPO)-inhibitor resistance was observed in 2001 in common waterhemp [Amaranthus tuberculatus (Moq.) Sauer var. rudis (Sauer) Costea and Tardif]. This resistance in A. tuberculatus is most commonly conferred by deletion of the amino acid glycine at the 210th position (ΔGly-210) of the PPO enzyme (PPO2) encoded by PPX2. In a field in Kentucky in 2015, inadequate control of Amaranthus plants was observed following application of a PPO inhibitor. Morphological observations indicated that survivors included both A. tuberculatus and Palmer amaranth (Amaranthus palmeri S. Watson). Research was conducted to confirm species identities and resistance and then to determine whether resistance evolved independently in the two species or via hybridization. Results from a quantitative PCR assay based on the ribosomal internal transcribed spacer confirmed that both A. tuberculatus and A. palmeri coexisted in the field. The mutation conferring ΔGly-210 in PPO2 was identified in both species; phylogenetic analysis of a region of PPX2, however, indicated that the mutation evolved independently in the two species. Genotyping of greenhouse-grown plants that survived lactofen indicated that all A. tuberculatus survivors, but only a third of A. palmeri survivors, contained the ΔGly-210 mutation. Consequently, A. palmeri plants were evaluated for the presence of an arginine to glycine or methionine substitution at position 128 of PPO2 (Arg-128-Gly and Arg-128-Met). The Arg-128-Gly substitution was found to account for resistance that was not accounted for by the ΔGly-210 mutation in plants from the A. palmeri population. Results from this study provide a modern-day example of both parallel and convergent evolution occurring within a single field.

scholarly journals Comparing responses of sensitive and resistant populations of Palmer amaranth (Amaranthus palmeri) and waterhemp (Amaranthus tuberculatus var. rudis) to PPO inhibitors

2019 ◽  
Vol 34 (1) ◽  
pp. 140-146 ◽  
Author(s):  
Kathryn J. Lillie ◽  
Darci A. Giacomini ◽  
Patrick J. Tranel
Keyword(s):  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Resistant Population ◽  
Evolution Of Resistance ◽  
Amaranthus Tuberculatus ◽  
Inhibitor Resistance ◽  
Dose Responses ◽  
Sensitive Population ◽  
Respective Species ◽  
Better Than

AbstractResistance to protoporphyrinogen oxidase (PPO) inhibitors was first observed in waterhemp in 2001 and was conferred by the deletion of a glycine residue at the 210th position (ΔGly-210) of the PPO enzyme. PPO-inhibitor resistance in Palmer amaranth was first observed in 2011, 10 years later. The objectives of this study were to directly compare PPO inhibitor responses in plants of both species with or without the ΔGly-210 mutation. Using greenhouse experiments, early (EPOST) and late (LPOST) postemergence dose responses using lactofen and fomesafen, and preemergence (PRE) dose responses using fomesafen and flumioxazin, were obtained for a sensitive and resistant population each of waterhemp and Palmer amaranth. An additional spray study confirmed each sensitive population used in the dose responses was representative of its respective species, with regards to PPO-inhibitor sensitivity. When treated at either POST timing, Palmer amaranth was more tolerant than waterhemp, and the ΔGly-210 mutation provided greater resistance in Palmer amaranth (48-fold to >3,440-fold, depending on timing and herbicide) than in waterhemp (31-fold to 123-fold). The level of tolerance in Palmer amaranth was striking; the sensitive Palmer amaranth population treated LPOST survived as well or better than the resistant waterhemp population treated EPOST. With PRE applications, response differences both between species and between resistant and sensitive populations generally were less pronounced, relative to POST applications. Collectively, this research indicates Palmer amaranth tolerance to POST-applied PPO inhibitors could have initially slowed (relative to waterhemp) evolution of resistance to these herbicides, and resistant and sensitive populations of both species are more likely to be effectively controlled with PRE rather than POST applications.

scholarly journals Sex-specific markers for waterhemp (Amaranthus tuberculatus) and Palmer amaranth (Amaranthus palmeri)

Weed Science ◽  
2019 ◽  
Vol 67 (4) ◽  
pp. 412-418 ◽  
Author(s):  
Jacob S. Montgomery ◽  
Ahmed Sadeque ◽  
Darci A. Giacomini ◽  
Patrick J. Brown ◽  
Patrick J. Tranel
Keyword(s):  
Crop Production ◽  
Genetic Basis ◽  
The United States ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Data Set ◽  
Amaranthus Tuberculatus ◽  
Primer Sets ◽  
Male Specific ◽  
Specific Sequences

AbstractWaterhemp [Amaranthus tuberculatus (Moq.) J. D. Sauer] and Palmer amaranth (Amaranthus palmeri S. Watson) are troublesome weeds of row-crop production in the United States. Their dioecious reproductive systems ensure outcrossing, facilitating rapid evolution and distribution of resistances to multiple herbicides. Little is known, however, about the genetic basis of dioecy in Amaranthus species. In this work, we use restriction site–associated DNA sequencing (RAD-Seq) to investigate the genetic basis of sex determination in A. tuberculatus and A. palmeri. For each species, approximately 200 plants of each sex were sampled and used to create RAD-Seq libraries. The resulting libraries were separately bar-coded and then pooled for sequencing with the Illumina platform, yielding millions of 64-bp reads. These reads were analyzed to identify sex-specific and sex-biased sequences. We identified 345 male-specific sequences from the A. palmeri data set and 2,754 male-specific sequences in A. tuberculatus. An unexpected 723 female-specific sequences were identified in a subset of the A. tuberculatus females; subsequent research, however, indicated female specificity of these markers was limited to the population from which they were identified. Primer sets designed to specifically amplify male-specific sequences were tested for accuracy on multiple, geographically distinct populations of A. tuberculatus and A. palmeri, as well as other Amaranthus species. Two primer sets for A. palmeri and four primer sets for A. tuberculatus were each able to distinguish between male and female plants with at least 95% accuracy. In the near term, sex-specific markers will be useful to the A. tuberculatus and A. palmeri research communities (e.g., to predict sex for crossing experiments). In the long-term, this research will provide the foundational tools for detailed investigations into the molecular biology and evolution of dioecy in weedy Amaranthus species.

Confirmation and Characterization of Non–target site Resistance to Fomesafen in Palmer amaranth (Amaranthus palmeri)

Weed Science ◽  
2018 ◽  
Vol 66 (6) ◽  
pp. 702-709 ◽  
Author(s):  
Vijay K. Varanasi ◽  
Chad Brabham ◽  
Jason K. Norsworthy
Keyword(s):  
Cytochrome P450 ◽  
Cropping Systems ◽  
Palmer Amaranth ◽  
Target Site ◽  
Amaranthus Palmeri ◽  
Allelic Discrimination Assay ◽  
Allelic Discrimination ◽  
First Case ◽  
Target Site Resistance ◽  
Novel Target

AbstractPalmer amaranth (Amaranthus palmeri S. Watson), a dioecious summer annual species, is one of the most troublesome weeds in U.S. cropping systems. The evolution of resistance to protoporphyrinogen oxidase inhibitors in A. palmeri biotypes is a major cause of concern to soybean [Glycine max (L.) Merr.] and cotton (Gossypium hirsutum L.) growers in the midsouthern United States. The objective of this study was to confirm and characterize the non–target site mechanism in a fomesafen-resistant accession from Randolph County, AR (RCA). A dose–response assay was conducted to assess the level of fomesafen resistance, and based on the GR50 values, the RCA accession was 18-fold more resistant to fomesafen than a susceptible (S) biotype. A TaqMan allelic discrimination assay and sequencing of the target-site genes PPX2 and PPX1 revealed no known or novel target-site mutations. An SYBR Green assay indicated no difference in PPX2 gene expression between the RCA and S biotypes. To test whether fomesafen resistance is metabolic in nature, the RCA and the S biotypes were treated with different cytochrome P450 (amitrole, piperonyl butoxide [PBO], malathion) and glutathione S-transferase (GST) (4-chloro-7-nitrobenzofurazan [NBD-Cl]) inhibitors, either alone or in combination with fomesafen. Malathion followed by (fb) fomesafen in RCA showed the greatest reduction in survival (67%) and biomass (86%) compared with fomesafen alone (45% and 66%, respectively) at 2 wk after treatment. Interestingly, NBD-Cl fb fomesafen also resulted in low survival (35%) compared with the fomesafen-only treatment (55%). Applications of malathion or NBD-Cl preceding fomesafen treatment resulted in reversal of fomesafen resistance, indicating the existence of cytochrome P450– and GST-based non–target site mechanisms in the RCA accession. This study confirms the first case of non–target site resistance to fomesafen in A. palmeri.

scholarly journals Late-season surveys to document seed rain potential of Palmer amaranth (Amaranthus palmeri) and waterhemp (Amaranthus tuberculatus) in Texas cotton

PLoS ONE ◽  
2020 ◽  
Vol 15 (6) ◽  
pp. e0226054
Author(s):  
Kaisa Werner ◽  
Debalin Sarangi ◽  
Scott Nolte ◽  
Peter Dotray ◽  
Muthukumar Bagavathiannan
Keyword(s):  
Seed Rain ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Late Season ◽  
Amaranthus Tuberculatus

Biotypes of Palmer Amaranth (Amaranthus palmeri) and Common Waterhemp (Amaranthus rudis) are Resistant to Imazethapyr and Thifensulfuron

1995 ◽  
Vol 9 (1) ◽  
pp. 192-195 ◽  
Author(s):  
Michael J. Horak ◽  
Dallas E. Peterson
Keyword(s):  
Herbicide Resistance ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Typical Pattern ◽  
Resistance Development ◽  
Common Waterhemp ◽  
Herbicide Resistant ◽  
Amaranthus Rudis ◽  
History Of ◽  
History Of Use

Seeds of suspected herbicide-resistant Palmer amaranth and common waterhemp were collected in Clay County and Douglas County, KS, respectively. An experiment was established in a greenhouse to determine if these species had developed resistance to imazethapyr and thifensulfuron. Imazethapyr was applied pre- (PRE) and postemergence (POST) at 1×, 2×, 4×, and 8× the suggested use rate (70 g/ha), and thifensulfuron was applied POST at 1×, 2×, 4×, and 8× the suggested use rate (4.5 g/ha). Both species had developed resistance to all rates of these herbicides. The occurrence of resistance at the Clay County site (Palmer amaranth) fit the typical pattern for the development of herbicide resistance, i.e., multiple applications of the same class of herbicide for several years. However, the Douglas County (common waterhemp) site had a limited history of use of ALS-inhibiting herbicides and did not follow typical models of resistance development.

Transfer and Expression of ALS Inhibitor Resistance from Palmer Amaranth (Amaranthus palmeri) to anA. spinosus×A. palmeriHybrid

Weed Science ◽  
2016 ◽  
Vol 64 (2) ◽  
pp. 240-247 ◽  
Author(s):  
William T. Molin ◽  
Vijay K. Nandula ◽  
Alice A. Wright ◽  
Jason A. Bond
Keyword(s):  
Field Experiments ◽  
Acetolactate Synthase ◽  
Palmer Amaranth ◽  
Enzyme Assays ◽  
Amaranthus Palmeri ◽  
Weed Species ◽  
Als Inhibitors ◽  
Inhibitor Resistance ◽  
Als Inhibitor ◽  
Interspecific Transfer

Transfer of herbicide resistance among closely related weed species is a topic of growing concern. A spiny amaranth × Palmer amaranth hybrid was confirmed resistant to several acetolactate synthase (ALS) inhibitors including imazethapyr, nicosulfuron, pyrithiobac, and trifloxysulfuron. Enzyme assays indicated that the ALS enzyme was insensitive to pyrithiobac and sequencing revealed the presence of a known resistance conferring point mutation, Trp574Leu. Alignment of the ALS gene for Palmer amaranth, spiny amaranth, and putative hybrids revealed the presence of Palmer amaranth ALS sequence in the hybrids rather than spiny amaranth ALS sequences. In addition, sequence upstream of the ALS in the hybrids matched Palmer amaranth and not spiny amaranth. The potential for transfer of ALS inhibitor resistance by hybridization has been demonstrated in the greenhouse and in field experiments. This is the first report of gene transfer for ALS inhibitor resistance documented to occur in the field without artificial/human intervention. These results highlight the need to control related species in both field and surrounding noncrop areas to avoid interspecific transfer of resistance genes.

scholarly journals Seedbank Persistence of Palmer Amaranth (Amaranthus palmeri) and Waterhemp (Amaranthus tuberculatus) across Diverse Geographical Regions in the United States

Weed Science ◽  
2018 ◽  
Vol 66 (4) ◽  
pp. 446-456 ◽  
Author(s):  
Nicholas E. Korres ◽  
Jason K. Norsworthy ◽  
Bryan G. Young ◽  
Daniel B. Reynolds ◽  
William G. Johnson ◽  
...  
Keyword(s):  
United States ◽  
Seed Viability ◽  
Soil Surface ◽  
The United States ◽  
Palmer Amaranth ◽  
Soil Conditions ◽  
Burial Depth ◽  
Amaranthus Palmeri ◽  
Seed Damage ◽  
Amaranthus Tuberculatus

AbstractKnowledge of the effects of burial depth and burial duration on seed viability and, consequently, seedbank persistence of Palmer amaranth (Amaranthus palmeriS. Watson) and waterhemp [Amaranthus tuberculatus(Moq.) J. D. Sauer] ecotypes can be used for the development of efficient weed management programs. This is of particular interest, given the great fecundity of both species and, consequently, their high seedbank replenishment potential. Seeds of both species collected from five different locations across the United States were investigated in seven states (sites) with different soil and climatic conditions. Seeds were placed at two depths (0 and 15 cm) for 3 yr. Each year, seeds were retrieved, and seed damage (shrunken, malformed, or broken) plus losses (deteriorated and futile germination) and viability were evaluated. Greater seed damage plus loss averaged across seed origin, burial depth, and year was recorded for lots tested at Illinois (51.3% and 51.8%) followed by Tennessee (40.5% and 45.1%) and Missouri (39.2% and 42%) forA. palmeriandA. tuberculatus, respectively. The site differences for seed persistence were probably due to higher volumetric water content at these sites. Rates of seed demise were directly proportional to burial depth (α=0.001), whereas the percentage of viable seeds recovered after 36 mo on the soil surface ranged from 4.1% to 4.3% compared with 5% to 5.3% at the 15-cm depth forA. palmeriandA. tuberculatus, respectively. Seed viability loss was greater in the seeds placed on the soil surface compared with the buried seeds. The greatest influences on seed viability were burial conditions and time and site-specific soil conditions, more so than geographical location. Thus, management of these weed species should focus on reducing seed shattering, enhancing seed removal from the soil surface, or adjusting tillage systems.

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