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1.
PLoS One ; 15(8): e0238396, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32866180

RESUMO

The effect of different management techniques for plant control in the vineyard were compared in the present work, focusing on plant diversity preservation and management efficacy in a two-year experiment on vineyard row weed community. Biomass-fueled flame weeding (with two intensities) was applied as an innovative plant control technique in contrast to tillage and mowing practices. The results showed that flaming was comparable to tillage regarding weed control effectiveness, and was more efficient than mowing. However, species number and functional evenness were not substantially modified by changing the applied management technique. Functional trait analysis demonstrated that row management significantly affected the frequency of annual plants, plant height, root depth index, and the occurrence of plants with storage organs. As for species composition, meaningful differences were found: only the two flaming treatments (i.e. gentle vs intense) and the gentle flaming vs mowing had consistent species composition. Flame wedding showed some potential benefits in plant control in the vineyard by favouring small plant and controlling overall weed abundance. On the other hand, flaming favoured plant species with asexual reproduction, with a potential negative impact on weed-vine competition and species persistence in the vineyard. Further studies are required to investigate such contrasting aspects, also considering other weed control techniques (e.g. cover-crops), considering a sustainable perspective of an herbicide-free environment.


Assuntos
Produtos Agrícolas/crescimento & desenvolvimento , Plantas Daninhas/efeitos dos fármacos , Poaceae/crescimento & desenvolvimento , Controle de Plantas Daninhas/métodos , Agricultura/métodos , Biodiversidade , Biomassa , Produtos Agrícolas/efeitos dos fármacos , Fazendas , Herbicidas/farmacologia , Plantas/efeitos dos fármacos , Poaceae/efeitos dos fármacos
2.
Pestic Biochem Physiol ; 170: 104684, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32980064

RESUMO

As important chemical pesticides, protoporphyrinogen oxidase (PPO, EC 1.3.3.4) herbicides play a vital role in weed management. Herein, in a search for novel PPO herbicides, a series of phenoxypyridine-2-pyrrolidinone derivatives were synthesized and their herbicidal activities were tested. To confirm the structures of the newly synthesized compounds, a colorless single crystal of compound 9d was obtained and crystallographic data collected. PPO inhibition experiments showed that most compounds have PPO inhibitory effects. The half-maximal inhibitory concentration (IC50) of compound 9d and oxyfluorfen were 0.041 mg/L and 0.043 mg/L, respectively, which showed compound 9d was the most potent compound. Compound 9d reduced the Chlorophyll a (Chl a) and Chlorophyll b (Chl b) contents of Abutilon theophrasti (A. theophrasti), to 0.306 and 0.217 mg/g, respectively. Crop selectivity experiments and field trial indicated that compound 9d can potentially be used to develop post-emergence herbicides for weed control in rice, cotton, and peanut. Molecular docking studies showed that both oxyfluorfen and compound 9d can enter the PPO cavity to occupy the active site and compete with the porphyrin to block the chlorophyll synthesis process, affect photosynthesis, and eventually cause weed death. Compound 9d was found to be a promising lead compound for novel herbicide development.


Assuntos
Clorofila A , Herbicidas/farmacologia , Inibidores Enzimáticos/farmacologia , Simulação de Acoplamento Molecular , Protoporfirinogênio Oxidase , Piridinas/farmacologia , Pirrolidinonas , Relação Estrutura-Atividade
3.
Pestic Biochem Physiol ; 169: 104653, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32828371

RESUMO

Descurainia sophia L. is one of the most notorious broadleaf weeds in winter wheat fields of China. In this study, 95 out of 163 (58.3%) D. sophia populations which were collected from provinces of Hebei, Shandong, Henan, Shanxi, Shaanxi and Jiangsu, have evolved resistance to tribenuron-methyl. The als1 and als2 were cloned in all test D. sophia populations, while als3 and als4 were identified only in some of the populations. Resistant mutations of Pro-197-Ser/Thr/Leu/His/Ala/Arg, Asp-376-Glu and Trp-574-Leu were identified in tribenuron-methyl-resistant (TR) D. sophia plants, while the Pro-197-Arg was first identified in D. sophia in this study. These resistant mutations displayed no preference between ALS1 and ALS2. However, Pro-197-Ser/Thr and Trp-574-Leu were identified in all ALS isozymes, while the other mutations were not. In addition, some resistant mutations displayed regional differences, the frequency of Pro-197-Ser in Shandong and Trp-574-Leu in Shanxi province is much higher than that in other provinces.


Assuntos
Acetolactato Sintase/genética , Brassicaceae/efeitos dos fármacos , Herbicidas/farmacologia , Esclerose Amiotrófica Lateral , Sulfonatos de Arila , China , Resistência a Herbicidas , Isoenzimas/genética , Mutação
4.
PLoS One ; 15(8): e0238144, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32857790

RESUMO

The efficacy of auxinic herbicides, a valuable weed control tool for growers worldwide, has been shown to vary with the time of day in which applications are made. However, little is known about the mechanisms causing this phenomenon. Investigating the differential in planta behavior of these herbicides across different times of application may grant an ability to advise which properties of auxinic herbicides are desirable when applications must be made around the clock. Radiolabeled herbicide experiments demonstrated a likely increase in ATP-binding cassette subfamily B (ABCB)-mediated 2,4-D and dicamba transport in Palmer amaranth (Amaranthus palmeri S. Watson) at simulated dawn compared to mid-day, as dose response models indicated that many orders of magnitude higher concentrations of N-1-naphthylphthalamic acid (NPA) and verapamil, respectively, are required to inhibit translocation by 50% at simulated sunrise compared to mid-day. Gas chromatographic analysis displayed that ethylene evolution in A. palmeri was higher when dicamba was applied during mid-day compared to sunrise. Furthermore, it was found that inhibition of translocation via 2,3,5-triiodobenzoic acid (TIBA) resulted in an increased amount of 2,4-D-induced ethylene evolution at sunrise, and the inhibition of dicamba translocation via NPA reversed the difference in ethylene evolution across time of application. Dawn applications of these herbicides were associated with increased expression of a putative 9-cis-epoxycarotenoid dioxygenase biosynthesis gene NCED1, while there was a notable lack of trends observed across times of day and across herbicides with ACS1, encoding 1-aminocyclopropane-1-carboxylic acid synthase. Overall, this research indicates that translocation is differentially regulated via specific protein-level mechanisms across times of application, and that ethylene release, a chief phytotoxic process involved in the response to auxinic herbicides, is related to translocation. Furthermore, transcriptional regulation of abscisic acid involvement in phytotoxicity and/or translocation are suggested.


Assuntos
Amaranthus/efeitos dos fármacos , Amaranthus/fisiologia , Resistência a Herbicidas/fisiologia , Herbicidas/farmacologia , Fotoperíodo , Ácido 2,4-Diclorofenoxiacético/farmacologia , Dicamba/farmacologia , Relação Dose-Resposta a Droga , Etilenos/metabolismo , Ftalimidas/metabolismo , Proteínas de Plantas/metabolismo , Ácidos Tri-Iodobenzoicos/metabolismo , Verapamil/metabolismo
5.
Pestic Biochem Physiol ; 168: 104634, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32711768

RESUMO

Multiple-herbicide resistance (MHR) in barnyardgrass (Echinochloa crus-galli) is a threat to rice production. The Ala-205-Val mutation in acetolactate synthase (ALS) conferred resistance to several ALS inhibitors in the E. crus-galli population AXXZ-2; consequently, ALS-inhibitors were unable to control this noxious weed species. In the present study, the sensitivity to acetyl-coenzyme A carboxylase (ACCase) herbicides and other herbicides having different modes of action was evaluated to determine an effective strategy for chemical weed control. Compared with that of the reportedly sensitive population JLGY-3, the AXXZ-2 population showed differential resistance to three ACCase-inhibitors (cyhalofop-butyl, fenoxaprop-P-ethyl, and pinoxaden), in addition to quinclorac and pretilachlor. A novel substitution (Asp-2078-Glu) in ACCase was detected as the main target-site resistance mechanisms in the AXXZ-2 population. Structural modeling of the mutant ACCase protein predicted that Asp-2078-Glu confers resistance to three ACCase inhibitors by reducing the binding affinity between them and the ACCase protein. To the best of our knowledge, this is the first study to report that the novel Asp-2078-Glu mutation confers resistance to several ACCase inhibitors. Target-site mutations in ALS and ACCase were detected in this MHR population. Except for quinclorac, pretilachlor, ALS inhibitors, and the three ACCase inhibitors, a number of herbicides remain effective in controlling this MHR E. crus-galli population.


Assuntos
Echinochloa/efeitos dos fármacos , Herbicidas/farmacologia , Acetil-CoA Carboxilase/genética , Resistência a Herbicidas , Mutação , Proteínas de Plantas/genética
6.
Food Chem ; 332: 127422, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32623129

RESUMO

During wheat cultivation, glyphosate-based herbicides are recommended to be applied a week prior to harvest during the ripe stage of physiological maturity. However, some grains may not be at this physiological stage due to non-uniform maturation within the field. The goal of this study was to determine the effect of glyphosate-based herbicide timing on the chemistry of wheat gluten proteins and shikimic acid accumulation. The results of the study indicate that pre-harvest glyphosate application does not impact the amino acid composition, protein secondary structure or gluten protein composition. However, pre-harvest glyphosate application decreased the molecular weight of SDS extractable and unextractable proteins, and significantly increased the amount of shikimic acid accumulation, especially when applied early. Thus, this study indicates that pre-harvest use of glyphosate-based herbicides can cause significant differences in wheat protein chemistry and shikimic acid levels, especially when applied earlier than recommended, emphasizing the importance of timely application.


Assuntos
Glicina/análogos & derivados , Herbicidas/farmacologia , Proteínas de Plantas/metabolismo , Ácido Chiquímico/metabolismo , Triticum/efeitos dos fármacos , Aminoácidos/análise , Aminoácidos/metabolismo , Glutens/análise , Glutens/metabolismo , Glicina/farmacologia , Proteínas de Plantas/análise , Ácido Chiquímico/análise , Triticum/química , Triticum/crescimento & desenvolvimento , Triticum/metabolismo
7.
An Acad Bras Cienc ; 92(2): e20180445, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32556045

RESUMO

The present work evaluated the ecological risk of glyphosate by its commercial formulation (Roundup Original®) used to control floating aquatic macrophytes. Exposure analysis and ecological effects were performed from microcosm studies. The risk characterization was performed based on the calculation of the risk quotient. The commercial formulation of glyphosate had high toxicity when it was assessed separately. On the other hand, ecotoxicological evaluation of water samples from microcosms did not present toxicity to any tested organisms, however, glyphosate application is recommended exclusively to water bodies that have the surface completely covered by macrophytes.


Assuntos
Glicina/análogos & derivados , Herbicidas/farmacologia , Poluentes Químicos da Água/farmacologia , Animais , Glicina/farmacologia , Modelos Biológicos , Medição de Risco , Testes de Toxicidade Aguda/métodos
8.
PLoS One ; 15(6): e0235394, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32598352

RESUMO

Several Amaranthus spp. around the world have evolved resistance (and cross resistance) to various herbicide mechanisms of action. Populations of redroot pigweed (RRPW-R) and tall waterhemp (TW-R) in Mississippi, USA have been suspected to be resistant to one or more acetolactate synthase (ALS) inhibiting herbicides. Whole plant dose-response experiments with multiple ALS inhibitors, ALS enzyme assays with pyrithiobac, and molecular sequence analysis of ALS gene constructs were conducted to confirm and characterize the resistance profile and nature of the mechanism in the RRPW-R and TW-R populations. Two susceptible populations, RRPW-S and TW-S were included for comparison with RRPW-R and TW-R, correspondingly. The resistance index (R/S; the herbicide dose required to reduce plant growth by 50% of resistant population compared to the respective susceptible population) values of the RRPW-R population were 1476, 3500, and 900 for pyrithiobac, imazaquin, and trifloxysulfuron, respectively. The R/S values of the TW-R population for pyrithiobac, imazaquin, and trifloxysulfuron were 51, 950, and 2600, respectively. I50 values of RRPW-S and RRPW-R populations for pyrithiobac were 0.062 and 208.33 µM, indicating that the ALS enzyme of the RRPW-R population is 3360-fold more resistant to pyrithiobac than the RRPW-S population under our experimental conditions. The ALS enzyme of the TW-R population was 1214-fold resistant to pyrithiobac compared to the TW-S population, with the I50 values for pyrithiobac of ALS from TW-R and TW-S populations being 87.4 and 0.072 µM, correspondingly. Sequencing of the ALS gene identified a point mutation at position 574 of the ALS gene leading to substitution of tryptophan (W) residue with a leucine (L) residue in both RRPW-R and TW-R populations. Thus, the RRPW-R and TW-R populations are resistant to several ALS-inhibiting herbicides belonging to different chemical classes due to an altered target site, i.e., ALS. Resistance in Amaranthus spp. to commonly used ALS-inhibiting herbicides warrants an integrated weed management scheme incorporating chemical, mechanical, and cultural strategies by growers.


Assuntos
Acetolactato Sintase/antagonistas & inibidores , Acetolactato Sintase/genética , Amaranthus/efeitos dos fármacos , Resistência a Herbicidas , Herbicidas/farmacologia , Mutação , Proteínas de Plantas/antagonistas & inibidores , Acetolactato Sintase/metabolismo , Amaranthus/classificação , Amaranthus/enzimologia , Amaranthus/genética , Substituição de Aminoácidos , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo
9.
PLoS One ; 15(5): e0233503, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32442184

RESUMO

Recently-emerged base editing technologies could create single base mutations at precise genomic positions without generation DNA double strand breaks. Herbicide resistant mutations have been successfully introduced to different plant species, including Arabidopsis, watermelon, wheat, potato and tomato via C to T (or G to A on the complementary strand) base editors (CBE) at the P197 position of endogenous acetolactate synthase (ALS) genes. Additionally, G to A conversion to another conserved amino acid S653 on ALS gene could confer tolerance to imidazolinone herbicides. However, no such mutation was successfully generated via CBE, likely due to the target C base is outside of the classic base editing window. Since CBE driven by egg cell (EC) specific promoter would re-edit the wild type alleles in egg cells and early embryos, we hypothesized the diversity of base editing outcomes could be largely increased at later generations to allow selection of desired herbicide resistant mutants. To test this hypothesis, we aimed to introduce C to T conversion to the complement strand of S653 codon at ALS gene, hosting a C at the 10th position within the 20-nt spacer sequence outside of the classic base editing window. While we did not detect base-edited T1 plants, efficient and diverse base edits emerged at later generations. Herbicide resistant mutants with different editing outcomes were recovered when T3 and T4 seeds were subject to herbicide selection. As expected, most herbicide resistant plants contained S653N mutation as a result of G10 to A10. Our results showed that CBE could create imidazolinone herbicide resistant trait in Arabidopsis and be potentially applied to crops to facilitate weed control.


Assuntos
Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Resistência a Herbicidas/genética , Acetolactato Sintase/genética , Substituição de Aminoácidos , Proteínas de Arabidopsis/genética , Sequência de Bases , Sistemas CRISPR-Cas , DNA de Plantas/genética , Edição de Genes , Genes de Plantas , Herbicidas/farmacologia , Imidazolinas/farmacologia , Mutagênese Sítio-Dirigida , Melhoramento Vegetal , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/genética , Seleção Genética , Controle de Plantas Daninhas
10.
Artigo em Inglês | MEDLINE | ID: mdl-32353674

RESUMO

Herbicides that inhibit acetyl-coenzyme A carboxylase (ACCase) are commonly used to control weedy grasses such as short-spike canarygrass (Phalaris brachystachys). Two resistant biotypes of P. brachystachys (R1 and R2) were found in different winter wheat fields in Iran. This study was done to confirm the suspected resistance observed in the field and to elucidate the resistance mechanisms involved. The results indicated that the both resistant biotypes showed cross-resistance to diclofop-methyl (DM), pinoxaden (PN) and cycloxydim (CD) herbicides. Based on the herbicide dose that inhibited 50% of the ACCase activity (I50), the ACCase activity of the resistant biotypes was less sensitive than the S biotype to DM, CD, and PN. No differences in translocation were detected between biotypes; most of the herbicide remained in the treated leaves. The 14C-DM metabolites were identified using thin-layer chromatography. Pre-treatment with the cytochrome P450 inhibitor ABT inhibited 14C-DM metabolism in the R1 biotype, indicating that metabolism is involved in the DM resistance in the R1 biotype. DNA sequencing studies found an Ile-1781-Thr change in both resistant biotypes, conferring cross-resistance to ACCase inhibitors. In general, in the R1 biotype which showed a higher level of resistance than that of the R2 biotype, cross-resistance was observed because of mutation and DM metabolism, while in the R2 biotype, the mutation confers resistance to ACCase-inhibiting herbicides. This is the first reported evidence of the mechanisms responsible for the resistance to ACCase herbicides in P. brachystachys. These results could be useful for improved management of resistant biotypes carrying similar mutations.


Assuntos
Resistência a Herbicidas , Herbicidas , Phalaris , Acetil-CoA Carboxilase/antagonistas & inibidores , Resistência a Herbicidas/genética , Herbicidas/farmacologia , Irã (Geográfico) , Mutação , Phalaris/efeitos dos fármacos , Phalaris/genética
11.
Environ Sci Pollut Res Int ; 27(15): 17692-17705, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32246421

RESUMO

Weeds are a major constraint to crop production and a barrier to human efforts to meet the ever-rising global demand for food, fibre and fuel. Managing weeds solely with herbicides is unsustainable due to the rapid evolution of herbicide-resistant weeds. Precise knowledge of the ecology and biology of weeds is of utmost importance to determine the most appropriate nonchemical management techniques. Raphanus raphanistrum L. is an extremely invasive and noxious weed due to its prolific seed production, allelopathic potential, multiple herbicide resistance and biological potential. R. raphanistrum causes high crop yield losses and thus has become one of the most troublesome agricultural and environmental weeds. R. raphanistrum could exchange pollen with herbicide-tolerant canola and could become an environmental threat. This weed has evolved resistance to many herbicides, and relying exclusively on herbicide-based management could lead to severe crop loss and uneconomical cropping. Although reviews are available on the ecology and biology of R. raphanistrum, significant changes in tillage, weed management and agronomic practices have been occurring worldwide. Therefore, it is timely to review the status of noxious weeds in different agro-ecological zones and management scenarios. This review focuses on the response of R. raphanistrum to different cultural, mechanical, biological, chemical and integrated management strategies practiced in various agro-ecosystems, and its biological potential to thrive under different weed management tactics. In addition, this review facilitates a better understanding of R. raphanistrum and describes how weed management outcomes could be improved through exploiting the biology and ecology of the weed.


Assuntos
Herbicidas/farmacologia , Raphanus/efeitos dos fármacos , Produtos Agrícolas/efeitos dos fármacos , Ecossistema , Resistência a Herbicidas , Plantas Daninhas/efeitos dos fármacos , Controle de Plantas Daninhas
12.
Artigo em Inglês | MEDLINE | ID: mdl-32289637

RESUMO

Acetohydroxyacid synthase (AHAS, E.C. 2.2.1.6) is the target site of several herbicide classes including imidazolinones. Imidazolinone resistance in wheat is conferred by two major genes AhasL-D1 and AhasL-B1. The objective of this work was to evaluate the in vitro and in vivo AHAS activity and plant growth in response to imazamox of nine wheat cultivars. Dose-response curves for two-gene resistant cultivars were significantly different from the single-gene resistant and susceptible cultivars in the in vitro AHAS assay. Resistance levels at the in vivo AHAS and whole-plant assays for resistant cultivars were >10-fold higher than susceptible cultivars. Moreover, in vivo dose-response curves showed differences among cultivars with the same number of resistance genes. It was concluded that in the in vitro AHAS assay cultivar variability was due to differences in target-site sensitivity while the in vivo AHAS assay reflected the resistance at whole-plant level. Both in vitro and in vivo AHAS dose-response curves could be useful tools when exploring mechanisms involved in imidazolinone resistance in different wheat genetic backgrounds and for the selection of higher resistant genotypes.


Assuntos
Acetolactato Sintase , Agricultura , Ensaios Enzimáticos , Resistência a Herbicidas , Imidazóis , Triticum , Acetolactato Sintase/genética , Agricultura/métodos , Resistência a Medicamentos/genética , Resistência a Herbicidas/genética , Herbicidas/farmacologia , Imidazóis/farmacologia , Seleção Genética , Triticum/efeitos dos fármacos , Triticum/enzimologia
13.
Microbes Environ ; 35(2)2020.
Artigo em Inglês | MEDLINE | ID: mdl-32269200

RESUMO

Atrazine is a triazine herbicide that is widely used to control broadleaf weeds. Its widespread use over the last 50 years has led to the potential contamination of soils, groundwater, rivers, and lakes. Its main route of complete degradation is via biological means, which is carried out by soil microbiota using a 6-step pathway. The aim of the present study was to investigate whether application of atrazine to soil changes the soil bacterial community. We used 16S rRNA gene sequencing and qPCR to elucidate the microbial community structure and assess the abundance of the atrazine degradation genes atzA, atzD, and trzN in a Brazilian soil. The results obtained showed that the relative abundance of atzA and trzN, encoding triazine-initiating metabolism in Gram-negative and -positive bacteria, respectively, increased in soil during the first weeks following the application of atrazine. In contrast, the abundance of atzD, encoding cyanuric acid amidohydrolase-the fourth step in the pathway-was not related to the atrazine treatment. Moreover, the overall soil bacterial community showed no significant changes after the application of atrazine. Despite this, we observed increases in the relative abundance of bacterial families in the 4th and 8th weeks following the atrazine treatment, which may have been related to higher copy numbers of atzA and trzN, in part due to the release of nitrogen from the herbicide. The present results revealed that while the application of atrazine may temporarily increase the quantities of the atzA and trzN genes in a Brazilian Red Latosol soil, it does not lead to significant and long-term changes in the bacterial community structure.


Assuntos
Atrazina/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Herbicidas/farmacologia , Microbiota/efeitos dos fármacos , Microbiologia do Solo , Biodegradação Ambiental , Brasil , Genes Bacterianos , Bactérias Gram-Negativas/classificação , Bactérias Gram-Positivas/classificação , RNA Ribossômico 16S/genética , Solo/química , Poluentes do Solo/farmacologia , Clima Tropical
14.
PLoS One ; 15(3): e0229909, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32134988

RESUMO

Stable transformation of common bean (Phaseolus vulgaris L.) has been successful, to date, only using biolistic-mediated transformation and shoot regeneration from meristem-containing embryo axes. In this study, using precultured embryo axes, and optimal co-cultivation conditions resulted in a successful transformation of the common bean cultivar Olathe using Agrobacterium tumefaciens strain EHA105. Plant regeneration through somatic embryogenesis was attained through the preculture of embryo axes for 12 weeks using induced competent cells for A. tumefaciens-mediated gene delivery. Using A. tumefaciens at a low optical density (OD) of 0.1 at a wavelength of 600 nm for infection and 4-day co-cultivation, compared to OD600 of 0.5, increased the survival rate of the inoculated explants from 23% to 45%. Selection using 0.5 mg L-1 glufosinate (GS) was effective to identify transformed cells when the bialaphos resistance (bar) gene under the constitutive 35S promoter was used as a selectable marker. After an 18-week selection period, 1.5% -2.5% inoculated explants, in three experiments with a total of 600 explants, produced GS-resistant plants through somatic embryogenesis. The expression of bar was confirmed in first- and second-generation seedlings of the two lines through reverse polymerase chain reaction. Presence of the bar gene was verified through genome sequencing of two selected transgenic lines. The induction of regenerable, competent cells is key for the successful transformation, and the protocols described may be useful for future transformation of additional Phaseolus germplasm.


Assuntos
Agrobacterium tumefaciens/genética , Phaseolus/genética , Melhoramento Vegetal/métodos , Plantas Geneticamente Modificadas/genética , Transformação Genética , Agrobacterium tumefaciens/efeitos dos fármacos , Aminobutiratos/farmacologia , DNA de Plantas/genética , Farmacorresistência Bacteriana/genética , Vetores Genéticos , Herbicidas/farmacologia , Compostos Organofosforados/farmacologia , Fenótipo , RNA de Plantas/genética
15.
PLoS One ; 15(3): e0230664, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32208460

RESUMO

Recent empirical evidence suggests that herbicides have damaging effects on non-target organisms in both natural and semi-natural ecosystems. The African mound building termite, Macrotermes bellicosus, is an important beneficial insect that functions as an ecosystem engineer due to its role in the breakdown of dead and decaying materials. Here, we examined the effects of 2,4-D amine salt (2,4-D) and atrazine based herbicides viz. Vestamine® and Ultrazine® on the survival and locomotion response of M. bellicosus. Worker termites were treated with a range of concentrations of Vestamine® (the recommended concentration: 6.25 ml per 500 ml of water, 0.25- and 0.5-fold below the recommended concentration and distilled water as control) and Ultrazine® (the recommended concentration: 3.75 ml per 500 ml of water, 0.25-, 0.5-, 2.0- and 4-fold of the recommended concentration and distilled water as control) for 24 hours for the mortality test, and allowed to run for 15 seconds for the locomotion trial. All concentrations of both Vestamine® and Ultrazine® were highly toxic to worker termites and mortality increased as the concentration and time after treatment increased. For both herbicides, concentrations far less than the recommended rates caused 100% mortality. The speed of termites was significantly influenced by both Vestamine® and Ultrazine® as termites exposed to all tested concentrations of the herbicides exhibited reduced running speed than the control. These findings suggest that beneficial insects, especially M. bellicosus may experience high mortality (up to 100%) and reduced mobility if they are sprayed upon or come in contact with plant materials that have been freshly sprayed with (less or more than) the recommended concentrations of Vestamine® and Ultrazine®. The findings of our study calls for the reassessment of the usage of 2,4-D and atrazine based herbicides in weed control in termite and other beneficial insect populated habitats.


Assuntos
Ácido 2,4-Diclorofenoxiacético/farmacologia , Atrazina/farmacologia , Herbicidas/farmacologia , Isópteros/fisiologia , Locomoção/efeitos dos fármacos , Animais , Ecossistema , Isópteros/efeitos dos fármacos
16.
J Agric Food Chem ; 68(10): 3017-3025, 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32059105

RESUMO

Chlorsulfuron has been applied in wheat fields as a recognized herbicide worldwide, yet it was officially banned in China since 2014 for its soil persistence problem. On the basis of our previous research that 5-dimethylamino distinctively accelerated degradation rate in soils, a modified amino moiety (Ia-c) and monosubstituted amino group (Id-e) were introduced onto the fifth position of the benzene ring in sulfonylurea structures, as well as heterocyclic amino substituents (If-g) to seek a suitable soil degradation rate during such an in situ crop rotation system. Referring to the biological data and ScAHAS inhibition and ScAHAS docking results, they turned out to be AHAS inhibitors with high potent herbicidal activities. The various influence on soil degradation rate along with crop safety indicated that different substituents on the fifth position have exerted an apparent impact. Their united study of structure-activity-safety-degradation relationship has great potential to provide valuable information for further development of eco-friendly agrochemicals.


Assuntos
Acetolactato Sintase/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Herbicidas/farmacologia , Proteínas de Plantas/antagonistas & inibidores , Poluentes do Solo/química , Compostos de Sulfonilureia/farmacologia , Acetolactato Sintase/metabolismo , Amaranthus/efeitos dos fármacos , Amaranthus/enzimologia , Brassica/efeitos dos fármacos , Brassica/enzimologia , Inibidores Enzimáticos/química , Herbicidas/química , Cinética , Modelos Moleculares , Proteínas de Plantas/metabolismo , Poluentes do Solo/farmacologia , Relação Estrutura-Atividade , Compostos de Sulfonilureia/química
17.
J Agric Food Chem ; 68(9): 2623-2630, 2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32058714

RESUMO

Eleusine indica is a typical xerophytic weed species with a cosmopolitan distribution. It is invasive and highly adaptable to diverse habitats and crops. Due to rice cropping-pattern changes, E indica has become one of the main dominant grass weeds infecting direct-seeding paddy fields. A Chinese E. indica population has evolved multiple-herbicide resistance to cyhalofop-butyl and glyphosate. In this study, the multiple-resistance profile of E. indica to these two different types of herbicides and their resistance mechanisms were investigated. Whole-plant dose-response assays indicated that the multiple-herbicide-resistant (MHR) population exhibited 10.8-fold resistance to cyhalofop-butyl and 3.1-fold resistance to glyphosate compared with the susceptible (S) population. ACCase sequencing revealed that the Asp-2078-Gly mutation was strongly associated with E. indica resistance to cyhalofop-butyl. The MHR plants accumulated less shikimic acid than S plants at 4, 6, and 8 days after glyphosate treatment. In addition, no amino acid substitution in the EPSPS gene was found in MHR plants. Further analysis revealed that the relative expression level of EPSPS in MHR plants was 6-10-fold higher than that in S plants following glyphosate treatment, indicating that EPSPS overexpression may contribute to the glyphosate resistance. Furthermore, the effectiveness of nine post-emergence herbicides against E. indica were evaluated, and one PPO inhibitor pyraclonil was identified as highly effective in controlling the S and MHR E. indica populations.


Assuntos
Butanos/farmacologia , Eleusine/efeitos dos fármacos , Glicina/análogos & derivados , Resistência a Herbicidas , Herbicidas/farmacologia , Nitrilos/farmacologia , Eleusine/genética , Eleusine/metabolismo , Regulação da Expressão Gênica de Plantas , Glicina/farmacologia , Oryza/crescimento & desenvolvimento , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/genética , Plantas Daninhas/metabolismo
18.
PLoS Genet ; 16(2): e1008593, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32012153

RESUMO

The repeated evolution of herbicide resistance has been cited as an example of genetic parallelism, wherein separate species or genetic lineages utilize the same genetic solution in response to selection. However, most studies that investigate the genetic basis of herbicide resistance examine the potential for changes in the protein targeted by the herbicide rather than considering genome-wide changes. We used a population genomics screen and targeted exome re-sequencing to uncover the potential genetic basis of glyphosate resistance in the common morning glory, Ipomoea purpurea, and to determine if genetic parallelism underlies the repeated evolution of resistance across replicate resistant populations. We found no evidence for changes in 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), glyphosate's target protein, that were associated with resistance, and instead identified five genomic regions that showed evidence of selection. Within these regions, genes involved in herbicide detoxification-cytochrome P450s, ABC transporters, and glycosyltransferases-are enriched and exhibit signs of selective sweeps. One region under selection shows parallel changes across all assayed resistant populations whereas other regions exhibit signs of divergence. Thus, while it appears that the physiological mechanism of resistance in this species is likely the same among resistant populations, we find patterns of both similar and divergent selection across separate resistant populations at particular loci.


Assuntos
Genoma de Planta/genética , Glicina/análogos & derivados , Herbicidas/farmacologia , Ipomoea/genética , Plantas Daninhas/genética , 3-Fosfoshikimato 1-Carboxiviniltransferase/antagonistas & inibidores , 3-Fosfoshikimato 1-Carboxiviniltransferase/genética , DNA de Plantas/genética , DNA de Plantas/isolamento & purificação , Evolução Molecular , Exoma/genética , Glicina/farmacologia , Resistência a Herbicidas/genética , Ipomoea/efeitos dos fármacos , Proteínas de Plantas/antagonistas & inibidores , Proteínas de Plantas/genética , Plantas Daninhas/efeitos dos fármacos , Sementes/efeitos dos fármacos , Sementes/genética , Seleção Genética , Análise de Sequência de DNA
19.
J Agric Food Chem ; 68(10): 3071-3078, 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32078770

RESUMO

This work reports halogenated 5-(2-hydroxyphenyl)pyrazoles as pseudilin analogues with the potential to target the enzyme IspD in the methylerythritol phosphate (MEP) pathway. Such analogues were designed using the bioisosteric replacement of the pseudilin core structure and synthesized via an efficient three-step route. With AtIspD-based screening and pre- and post-emergence herbicidal tests, these compounds were demonstrated to have considerable activities against AtIspD, with IC50 up to 3.27 µM, and against model plants rape and barnyard grass, with moderate to excellent activities. At a rate of 150 g/ha in the greenhouse test, three compounds exhibited higher or comparable herbicidal activities than pseudilin. Molecular docking of representative compounds into the allosteric site of AtIspD revealed a binding mode similar to that of pseudilin. The established bioisosterism and synthesis method in this work may serve as an important tool for the development of new herbicides and antimicrobials targeting IspD in the MEP pathway.


Assuntos
Echinochloa/enzimologia , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Herbicidas/química , Herbicidas/farmacologia , Proteínas de Plantas/antagonistas & inibidores , Pirazóis/química , Pirazóis/farmacologia , Echinochloa/efeitos dos fármacos , Echinochloa/genética , Echinochloa/metabolismo , Inibidores Enzimáticos/síntese química , Eritritol/metabolismo , Halogenação , Herbicidas/síntese química , Simulação de Acoplamento Molecular , Estrutura Molecular , Fosfatos/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Pirazóis/síntese química , Relação Estrutura-Atividade
20.
J Environ Sci Health B ; 55(5): 470-476, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32009547

RESUMO

A central pillar of modern weed control is the discovery of new herbicides which are nontoxic to humans and the environment and which have low application dosage. The natural products found in plants and microorganisms are well suited in this context because they are generally nontoxic and have a wide variety of biological activities. In this work, Diaporthe phaseolorum (Dp), Penicillium simplicissimum (Ps) and Trichoderma spirale (Ts) (methanolic extracts) were evaluated as photosynthesis and plant growth inhibitors in Senna occidentalis and Ipomoea grandifolia. The most significant results were observed for Ts and Dp in S. occidentalis and I. grandifolia, respectively. Ts reduced PI(abs), ET0/CS0, PHI(E0) and PSI0 parameters by 64, 28, 40 and 38%, respectively, indicating a reduction on electron transport efficiency. Additionally, Ts decreased shoot length by 9%, affecting the plant growth. Dp reduced PI(abs), ET0/CS0 and PHI(E0) parameters by 50, 20, 26 and 22%, respectively, revealing the inhibition competency on PSII acceptor site. Furthermore, Dp decreased by 50% the shoot length on germination assay. Thus, the phytotoxic behaviors based on endophytic fungal extracts may serve as a valuable tool in the further development of a bioherbicide since natural products represent an interesting alternative to replace commercial herbicides.


Assuntos
Endófitos/química , Herbicidas/farmacologia , Ipomoea/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Senna (Planta)/efeitos dos fármacos , Ascomicetos/química , Germinação/efeitos dos fármacos , Metanol , Penicillium/química , Reguladores de Crescimento de Planta/farmacologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Caules de Planta/efeitos dos fármacos , Caules de Planta/crescimento & desenvolvimento , Trichoderma/química , Controle de Plantas Daninhas/métodos
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