First Case of Glyphosate Resistance in Bromus catharticus Vahl.: Examination of Endowing Resistance Mechanisms

Bromus catharticus Vahl. has been used as a valuable forage crop, but it has also been noted as a weed of winter crops and an invader in several countries. In Argentina, a putative glyphosate-resistant population of B. catharticus was identified as a consequence of the lack of effective control with glyphosate in the pre-sowing of wheat. Plant survival and shikimate accumulation analysis demonstrated a lower glyphosate-sensitivity of this population in comparison to a susceptible B. catharticus population. The resistant population was 4-fold more resistant to glyphosate than its susceptible counterpart. There was no evidence of target-site mechanisms of glyphosate resistance or an enhanced capacity to metabolize glyphosate in the resistant population. However, the resistant plants showed a lower foliar retention of glyphosate (138.34 μl solution g−1 dry weight vs. 390.79 μl solution g−1 dry weight), a reduced absorption of 14C-glyphosate (54.18 vs. 73.56%) and lower translocation of 14C-glyphosate from the labeled leaf (27.70 vs. 62.36%). As a result, susceptible plants accumulated a 4.1-fold higher concentration of 14C-glyphosate in the roots compared to resistant plants. The current work describes the first worldwide case of glyphosate resistance in B. catharticus. A reduced foliar retention of herbicide, a differential rate of glyphosate entry into leaves and an altered glyphosate translocation pattern would be the most likely mechanisms of glyphosate exclusion.

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New Case of False-Star-Grass (Chloris distichophylla) Population Evolving Glyphosate Resistance

Agronomy ◽

10.3390/agronomy10030377 ◽

2020 ◽

Vol 10 (3) ◽

pp. 377 ◽

Cited By ~ 2

Author(s):

José G. Vázquez-García ◽

Sajedeh Golmohammadzadeh ◽

Candelario Palma-Bautista ◽

Antonia M. Rojano-Delgado ◽

José A. Domínguez-Valenzuela ◽

...

Keyword(s):

Weed Management ◽

Chemical Control ◽

Shikimic Acid ◽

Dry Weight ◽

Glyphosate Resistance ◽

Integrated Weed Management ◽

Resistance Level ◽

Susceptible Population ◽

First Case

Chloris distichophylla, suspected of glyphosate resistance (GR), was collected from areas of soybean cultivation in Rio Grande do Sul, Brazil. A comparison was made with a susceptible population (GS) to evaluate the resistance level, mechanisms involved, and control alternatives. Glyphosate doses required to reduce the dry weight (GR50) or cause a mortality rate of 50% (LD50) were around 5.1–3 times greater in the GR population than in the GS population. The shikimic acid accumulation was around 6.2-fold greater in GS plants than in GR plants. No metabolized glyphosate was found in either GR or GS plants. Both populations did not differ in the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) basal activity or in vitro inhibition of EPSPS activity by glyphosate (I50). The maximum glyphosate absorption was observed at 96 hours after treatment (HAT), which was twofold higher in the GS plants than in the GR plants. This confirms the first case of glyphosate resistance in C. distichophylla. In addition, at 96 HAT, the GS plants translocated more 14C-glyphosate than the GR ones. The best options for the chemical control of both C. distichophylla populations were clethodim, quizalofop, paraquat, glufosinate, tembotrione, diuron, and atrazine. The first case of glyphosate resistance in C. distichophylla was due to impaired uptake and translocation. Chemical control using multiple herbicides with different modes of action (MOA) could be a tool used for integrated weed management (IWM) programs.

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Target-site resistance to cyhalofop-butyl in bearded sprangletop (Diplachne fusca) from China

Weed Science ◽

10.1017/wsc.2019.23 ◽

2019 ◽

Vol 67 (05) ◽

pp. 534-538 ◽

Cited By ~ 1

Author(s):

Shuzhong Yuan ◽

Yingjie Di ◽

Yueyang Chen ◽

Yongrui Chen ◽

Jingxuan Cai ◽

...

Keyword(s):

Amino Acid Position ◽

Resistance Mechanisms ◽

Target Site ◽

Annual Grass ◽

Site Mutation ◽

Resistance Level ◽

First Case ◽

Resistant Population ◽

Target Site Resistance ◽

Grass Weed

AbstractBearded sprangletop [Diplachne fusca(L.) P. Beauv. ex Roem. & Schult. ssp.fascicularis(Lam.) P. M. Peterson & N. Snow] is a noxious annual grass weed of paddy fields, distributed in coastal regions of the Jiangsu and Hebei provinces in China. Cyhalofop-butyl has been widely used to control grass weeds since 2006 in China. Overreliance on cyhalofop-butyl has led to the evolution of resistant weeds. In this study, the resistance level and cyhalofop-butyl resistance mechanisms were investigated in the putative resistant (JSHH) population. The dose–response experiments showed that the JSHHD.fuscapopulation had evolved 8.9-fold resistance to cyhalofop-butyl. Acetyl-CoA carboxylase (ACCase) sequencing revealed a point mutation (GGC to GCC) at amino acid position 2096, resulting in a Gly-2096-Ala substitution in the resistant population. To our knowledge, this is the first case of cyhalofop-butyl resistance inD.fuscaand the first report of a target-site mutation conferring resistance to ACCase-inhibiting herbicides inD.fusca. In addition, the resistantD.fuscapopulation (JSHH) with the Gly-2096-Ala mutation was cross-resistant to the aryloxyphenoxypropionate herbicide metamifop, the cyclohexanedione herbicide sethoxydim, and the phenylpyrazolin herbicide pinoxaden.

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Is glyphosate-resistant ryegrass resistant to paraquat?

New Zealand Plant Protection ◽

10.30843/nzpp.2017.70.90 ◽

2017 ◽

Vol 70 ◽

pp. 323

Author(s):

H. Ghanizadeh ◽

K.C. Harrington

Keyword(s):

New Zealand ◽

Perennial Ryegrass ◽

Glyphosate Resistance ◽

Main Mechanism ◽

Susceptible Population ◽

Mechanism Of Resistance ◽

First Case ◽

Paraquat Resistance ◽

Resistant Population ◽

Translocation Mechanism

Sequestration of herbicide into vacuoles is considered to be the main mechanism of resistance to both glyphosate and paraquat worldwide. In New Zealand, the first case of glyphosate resistance was found in ryegrass (Lolium) species, and the restricted herbicide translocation was found to be the main mechanism of resistance in the studied populations, presumably through sequestration. Overseas researchers hypothesised that the mechanism responsible for glyphosate resistance could also cause resistance to paraquat. We examined this hypothesis by comparing a known glyphosate-resistant population of perennial ryegrass with a known susceptible population after spraying with different rates (25—800 g ai/ha) of paraquat. The glyphosate-resistant population responded similarly to the susceptible population at the different rates of paraquat application. This result suggests that the restricted glyphosate translocation mechanism does not necessarily lead to paraquat resistance. These results also suggest that paraquat could be useful for controlling ryegrass when glyphosate resistance has evolved and the application of paraquat is permitted.

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Non-Target Site Mechanisms Endow Resistance to Glyphosate in Saltmarsh Aster (Aster squamatus)

Plants ◽

10.3390/plants10091970 ◽

2021 ◽

Vol 10 (9) ◽

pp. 1970

Author(s):

José Alfredo Domínguez-Valenzuela ◽

Ricardo Alcántara-de la Cruz ◽

Candelario Palma-Bautista ◽

José Guadalupe Vázquez-García ◽

Hugo E. Cruz-Hipolito ◽

...

Keyword(s):

Shikimic Acid ◽

Glyphosate Resistance ◽

Resistance Mechanisms ◽

Target Site ◽

Weed Species ◽

The Third ◽

Citrus Groves ◽

First Case ◽

Treated Leaf ◽

Target Site Resistance

Of the six-glyphosate resistant weed species reported in Mexico, five were found in citrus groves. Here, the glyphosate susceptibility level and resistance mechanisms were evaluated in saltmarsh aster (Aster squamatus), a weed that also occurs in Mexican citrus groves. The R population accumulated 4.5-fold less shikimic acid than S population. S plants hardly survived at 125 g ae ha−1 while most of the R plants that were treated with 1000 g ae ha−1, which suffered a strong growth arrest, showed a vigorous regrowth from the third week after treatment. Further, 5-enolpyruvylshikimate-3-phosphate basal and enzymatic activities did not diverge between populations, suggesting the absence of target-site resistance mechanisms. At 96 h after treatment, R plants absorbed ~18% less glyphosate and maintained 63% of the 14C-glyphsoate absorbed in the treated leaf in comparison to S plants. R plants metabolized twice as much (72%) glyphosate to amino methyl phosphonic acid and glyoxylate as the S plants. Three non-target mechanisms, reduced absorption and translocation and increased metabolism, confer glyphosate resistance saltmarsh aster. This is the first case of glyphosate resistance recorded for A. squamatus in the world.

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Efficacy of Different Herbicides on Echinochloa colona (L.) Link Control and the First Case of Its Glyphosate Resistance in Greece

Agronomy ◽

10.3390/agronomy10071056 ◽

2020 ◽

Vol 10 (7) ◽

pp. 1056

Author(s):

Ilias Travlos ◽

Panagiotis Kanatas ◽

Anastasia Tsekoura ◽

Ioannis Gazoulis ◽

Panayiota Papastylianou ◽

...

Keyword(s):

Dose Response ◽

Weed Management ◽

Dry Weight ◽

Glyphosate Resistance ◽

Climatic Conditions ◽

Multiple Resistance ◽

Baseline Sensitivity ◽

Perennial Crops ◽

First Case ◽

Resistance Patterns

E. colona is a C4 annual summer grass which is troublesome to major summer annual and perennial crops. Due to recent complaints by the farmers, the objectives of the present study were to evaluate the efficacy of penoxsulam, profoxydim, cycloxydim, cyhalofop-butyl, florpyrauxifen-benzyl and glyphosate against six E. colona accessions, and also to evaluate the response of these accessions to different rates of glyphosate in a dose-response experiment. In the first experiment, herbicides were applied at their maximum recommended label rates, while in the dose-response experiment, glyphosate was applied at six doses corresponding to 0, 1/4X, 1/2X, X, 2X, and 4X of the recommended rate. The dry weight of the biotypes TH8 and TH7 treated with profoxydim was 66% and 68% of the untreated control, respectively. The efficacy of cyhalofop-butyl against three accessions was lower than 30%, while two accessions were susceptible to this herbicide. The efficacy of penoxsulam against the biotypes ET2 and ET4 was lower than 10%, while dry weight of FT5 and TH8 was only reduced by 23%–28% as compared to the control. Cycloxydim application provided control higher than 75% at 21 days after treatment (DAT) of three accessions, while the majority of E. colona accessions was adequately controlled by the application of florpyrauxifen-benzyl. The response of the different accessions to glyphosate varied. The results of the glyphosate dose-response experiment revealed that the GR50 values of the resistant E. colona accessions ET2 and ET4 were up to 1098 and 1220 g a.e. ha−1 of glyphosate, respectively, whereas the GR50 value of the susceptible accession (FT5) was only 98 g a.e. ha−1. The resistance indices of ET2 and ET4 were 12.4 and 11.2, respectively, indicating that they have already developed resistance to glyphosate. Three more accessions could be also of developing resistant to glyphosate. This is the first report of glyphosate resistance from E. colona accessions in Greece, with indications of multiple resistance also present. Further research is needed in order to evaluate the efficacy of several herbicides under different soil and climatic conditions, conduct baseline sensitivity studies, reveal the evolvement of resistance patterns to glyphosate from accessions of Echinochloa spp., and search for alternative options of weed management in annual and perennial crops due to the clear indications of multiple resistance situations.

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Evaluation of the Susceptibility of Some Eggplant Cultivars to Green Peach Aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae)

Agriculture ◽

10.3390/agriculture11010031 ◽

2021 ◽

Vol 11 (1) ◽

pp. 31

Author(s):

Zienab Raeyat ◽

Jabraiel Razmjou ◽

Bahram Naseri ◽

Asgar Ebadollahi ◽

Patcharin Krutmuang

Keyword(s):

Insect Pests ◽

Growth Parameters ◽

Green Peach Aphid ◽

Integrated Management ◽

Resistance Index ◽

Dry Weight ◽

Developmental Time ◽

Resistance Mechanisms ◽

Screening Tests ◽

Population Increase

Due to the detrimental side-effects of synthetic pesticides, the use of nonchemical strategies in the management of insect pests is necessary. In the present study, the susceptibility of fourteen eggplant cultivars to green peach aphid (M. persicae) were investigated. According to preliminary screening tests, ‘Long-Green’, ‘Ravaya’ and ‘Red-Round’ as relatively resistant, and ‘White-Casper’ and ‘Pearl-Round’ as susceptible cultivars were recognized. In the antixenosis tests, the highest hosting preference was documented for ‘White-Casper’. Population growth parameters were used for evaluation of antibiosis. The highest and lowest developmental time (d) was observed on ‘Long-Green’ (4.33 d) and ‘White-Casper’ (3.26 d), respectively. The highest and lowest intrinsic rates of population increase (rm) were on ‘White-Casper’ (0.384 d−1) and ‘Long-Green’ (0.265 d−1), respectively. Significant differences were observed in the height and fresh and dry weight of infested and noninfected plants. Plant resistance index (PRI), as a simplified way to assess all resistance mechanisms, provides a particular value to determine the proper resistant cultivar. The greatest PRI value was observed on ‘Long-Green’. In general, the ‘Long-Green’ showed the least, and the ‘White-Casper’ displayed the most susceptibility among tested cultivars infested by M. persicae, which might be useful in integrated management of this pest.

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Growth and dry matter partitioning response in cereal-legume intercropping under full and limited irrigation regimes

Scientific Reports ◽

10.1038/s41598-021-92022-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Amanullah ◽

Shah Khalid ◽

Farhan Khalil ◽

Mohamed Soliman Elshikh ◽

Mona S. Alwahibi ◽

...

Keyword(s):

Water Stress ◽

Dry Matter ◽

Dry Weight ◽

Pigeon Pea ◽

Growth Stages ◽

Dry Matter Partitioning ◽

Sole Crop ◽

Irrigation Regimes ◽

Storage Organs ◽

Winter Crops

AbstractThe dry matter partitioning is the product of the flow of assimilates from the source organs (leaves and stems) along the transport route to the storage organs (grains). A 2-year field experiment was conducted at the agronomy research farm of the University of Agriculture Peshawar, Pakistan during 2015–2016 (Y1) to 2016–2017 (Y2) having semiarid climate. Four summer crops, pearl millet (Pennisetum typhoidum L.), sorghum (Sorghum bicolor L.) and mungbean (Vigna radiata L.) and pigeonpea (Cajanus cajan L.) and four winter crops, wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), fababean (Vicia faba) and rapeseed (Brassica napus) were grown under two irrigation regimes (full vs. limited irrigation) with the pattern of growing each crop either alone as sole crop or in combination of two crops in each intercropping system under both winter and summer seasons. The result showed that under full irrigated condition (no water stress), all crops had higher crop growth rate (CGR), leaf dry weight (LDW), stem dry weight (SDW), and spike/head dry weight (S/H/PDW) at both anthesis and physiological maturity (PM) than limited irrigated condition (water stress). In winter crops, both wheat and barley grown as sole crop or intercropped with fababean produced maximum CGR, LDW, SDW, S/H/PDW than other intercrops. Among summer crops, sorghum intercropped either with pigeon pea or with mungbean produced maximum CGR, LDW, SDW, and S/H/PDW at both growth stages. Sole mungbean and pigeon pea or pigeon pea and mungbean intercropping had higher CGR, LDW, SDW, S/H/PDW than millet and sorghum intercropping. On the other hand, wheat and barley grown as sole crops or intercropped with fababean produced maximum CGR, LDW, SDW, and S/H/PDW than other intercrops. Fababean grown as sole crop or intercropped with wheat produced higher CGR, LDW, SDW, and S/H/PDW at PM than intercropped with barley or rapeseed. From the results it was concluded that cereal plus legume intercropping particularly wheat/fababean in winter and sorghum/pigeon pea or sorgum/mungbean in summer are the most productive intercropping systems under both low and high moisture regimes.

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The SCREENING OF HERBICIDES FOR EFFECTIVE CONTROL OF WEEDS IN SOYBEAN (Glycine max L.)

JOURNAL OF WEED SCIENCE RESEARCH ◽

10.28941/pjwsr.v26i3.862 ◽

2020 ◽

Vol 27 (2) ◽

pp. 251-266

Author(s):

Muhammad Ehsan Safdar ◽

Muhammad Ather Nadeem ◽

Abdul Rehman ◽

Amjed Ali ◽

Nasir Iqbal ◽

...

Keyword(s):

Seed Yield ◽

Soybean Seed ◽

Dry Weight ◽

Yield Component ◽

Effective Control ◽

College Of Agriculture ◽

Glycine Max L ◽

Relationship Of ◽

Moderate Relationship ◽

100 Seed Weight

Little is known about best herbicidal weed option for weed eradication in soybean in agro-climatic circumstances of Sargodha, Punjab, Pakistan. A two year field study was accomplished at College of Agriculture experimental site Sargodha in spring seasons of 2018 and 2019 to evaluate the efficacy of different herbicides adjacent to major weeds present in soybean. The study consisted of 8 herbicide treatments including two pre-emergence herbicides (pendimethalin at 489.1 g a.i. ha-1, pendimethalin + S-metolachlor at 731.1 g a.i. ha-1) which are applied immediately after sowing and six post-emergence herbicides (oxyfluorfen at 237.1 g a.i. ha-1, metribuzin at 518.7 g a.i. ha-1, quizalofop-p-ethyl at 148.2 g a.i. ha-1, acetochlor at 741 g a.i. ha-1, halosulfuron at 37 g a.i. ha-1and topramezone at 21.5 g a.iha-1) which were used 25 days subsequent to sowing. In contrast to control, all herbicides have shown significant decline in weed density (up to 94%) and dry weight (up to 88%); and caused significant increases in plant height (up to 85%), pod bearing branches (up to 77%), number of pods per plant (up to 83%), 100-seed weight (up to 37%) and seed yield (up to 160%) of soybean. Among herbicides, topramezone at 21.5 g a.i ha-1 gave significantly the highest (1234 and 1272 kg ha-1 in the year 2018 and 2019) seed yield of soybean and HEIs (1.28 and 1.03 in year 2018 and 2019, respectively). However, oxyfluorfen at 237.1 g a.i. ha-1, pendimethalin + S-metolachlor at 731.1 g a.i. ha-1, pendimethalin at 489.1 g a.i. ha-1, quizalofop-p-ethyl at 148.2 g a.i.ha-1 followed it. The regression analysis depicted a significant negative moderate relationship of soybean seed yield with weed dry weight (R2 = 0.7074), and pods per plant (R2 = 0.7012) was proved to be the main yield component responsible for higher yield of soybean.

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Genotypic Variationin Dry Weight and Nitrogen Concentration of Wheat Plant Parts; Relations to Grain Yield and Grain Protein Concentration

Journal of Agricultural Science ◽

10.5539/jas.v4n11p11 ◽

2012 ◽

Vol 4 (11) ◽

Author(s):

Ali Hafeez Malik ◽

Allan Andersson ◽

Ramune Kuktaite ◽

Muhammad Yaqub Mujahid ◽

Bismillah Khan ◽

...

Keyword(s):

Grain Yield ◽

Protein Concentration ◽

Nitrogen Concentration ◽

Wheat Plant ◽

Dry Weight ◽

Grain Protein ◽

Grain Protein Concentration ◽

Plant Parts

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Deciphering the Mechanism of Glyphosate Resistance in Amaranthus palmeri by Cytogenomics

Cytogenetic and Genome Research ◽

10.1159/000521409 ◽

2022 ◽

pp. 1-7

Author(s):

Dal-Hoe Koo ◽

Rajendran Sathishraj ◽

Bernd Friebe ◽

Bikram S. Gill

Keyword(s):

Genome Size ◽

Copy Number ◽

Fold Increase ◽

Glyphosate Resistance ◽

Resistance Mechanisms ◽

Fish Analysis ◽

Amaranthus Palmeri ◽

Artificial Chromosomes ◽

Genetic Elements ◽

Meiotic Chromosomes

In agriculture, various chemicals are used to control the weeds. Out of which, glyphosate is an important herbicide invariably used in the cultivation of glyphosate-resistant crops to control weeds. Overuse of glyphosate results in the evolution of glyphosate-resistant weeds. Evolution of glyphosate resistance (GR) in Amaranthus palmeri (AP) is a serious concern in the USA. Investigation of the mechanism of GR in AP identified different resistance mechanisms of which 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene amplification is predominant. Molecular analysis of GR AP identified the presence of a 5- to >160-fold increase in copies of the EPSPS gene than in a glyphosate-susceptible (GS) population. This increased copy number of the EPSPS gene increased the genome size ranging from 3.5 to 11.8%, depending on the copy number compared to the genome size of GS AP. FISH analysis using a 399-kb EPSPS cassette derived from bacterial artificial chromosomes (BACs) as probes identified that amplified EPSPS copies in GR AP exist in extrachromosomal circular DNA (eccDNA) in addition to the native copy in the chromosome. The EPSPS gene-containing eccDNA having a size of ∼400 kb is termed EPSPS-eccDNA and showed somatic mosacism in size and copy number. EPSPS-eccDNA has a genetic mechanism to tether randomly to mitotic or meiotic chromosomes during cell division or gamete formation and is inherited to daughter cells or progeny generating copy number variation. These eccDNAs are stable genetic elements that can replicate and exist independently. The genomic characterization of the EPSPS locus, along with the flanking regions, identified the presence of a complex array of repeats and mobile genetic elements. The cytogenomics approach in understanding the biology of EPSPS-eccDNA sheds light on various characteristics of EPSPS-eccDNA that favor GR in AP.

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