Mechanisms of Resistance to Insecticidal Proteins from Bacillus thuringiensis

2021 ◽  
Vol 66 (1) ◽  
pp. 121-140
Author(s):  
Juan Luis Jurat-Fuentes ◽  
David G. Heckel ◽  
Juan Ferré
Keyword(s):  
Bacillus Thuringiensis ◽  
Current Knowledge ◽  
Mechanisms Of Resistance ◽  
Insecticidal Proteins ◽  
Bt Toxins ◽  
Evolution Of Resistance ◽  
Synthetic Pesticides ◽  
Bacterium Bacillus ◽  
High Level ◽  
Level Resistance

Insecticidal proteins from the bacterium Bacillus thuringiensis ( Bt) are used in sprayable formulations or produced in transgenic crops as the most successful alternatives to synthetic pesticides. The most relevant threat to sustainability of Bt insecticidal proteins (toxins) is the evolution of resistance in target pests. To date, high-level resistance to Bt sprays has been limited to one species in the field and another in commercial greenhouses. In contrast, there are currently seven lepidopteran and one coleopteran species that have evolved practical resistance to transgenic plants producing insecticidal Bt proteins. In this article, we present a review of the current knowledge on mechanisms of resistance to Bt toxins, with emphasis on key resistance genes and field-evolved resistance, to support improvement of Bt technology and its sustainability.

scholarly journals Molecular pathways to high-level azithromycin resistance in Neisseria gonorrhoeae

2021 ◽  
Author(s):  
J G E Laumen ◽  
S S Manoharan-Basil ◽  
E Verhoeven ◽  
S Abdellati ◽  
I De Baetselier ◽  
...  
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Ribosomal Proteins ◽  
Efflux Pump ◽  
23S Rrna ◽  
Rrna Gene ◽  
23S Rrna Gene ◽  
Evolution Of Resistance ◽  
High Level ◽  
Azithromycin Resistance ◽  
Level Resistance

Abstract Background The prevalence of azithromycin resistance in Neisseria gonorrhoeae is increasing in numerous populations worldwide. Objectives To characterize the genetic pathways leading to high-level azithromycin resistance. Methods A customized morbidostat was used to subject two N. gonorrhoeae reference strains (WHO-F and WHO-X) to dynamically sustained azithromycin pressure. We tracked stepwise evolution of resistance by whole genome sequencing. Results Within 26 days, all cultures evolved high-level azithromycin resistance. Typically, the first step towards resistance was found in transitory mutations in genes rplD, rplV and rpmH (encoding the ribosomal proteins L4, L22 and L34 respectively), followed by mutations in the MtrCDE-encoded efflux pump and the 23S rRNA gene. Low- to high-level resistance was associated with mutations in the ribosomal proteins and MtrCDE efflux pump. However, high-level resistance was consistently associated with mutations in the 23S ribosomal RNA, mainly the well-known A2059G and C2611T mutations, but also at position A2058G. Conclusions This study enabled us to track previously reported mutations and identify novel mutations in ribosomal proteins (L4, L22 and L34) that may play a role in the genesis of azithromycin resistance in N. gonorrhoeae.

High-Level Resistance to Bacillus thuringiensis Toxin Cry1Ac and Cadherin Genotype in Pink Bollworm

2006 ◽  
Vol 99 (6) ◽  
pp. 2125-2131 ◽  
Author(s):  
Bruce E. Tabashnik ◽  
Robert W. Biggs ◽  
Jeffrey A. Fabrick ◽  
Aaron J. Gassmann ◽  
Timothy J. Dennehy ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Pink Bollworm ◽  
Bacillus Thuringiensis Toxin ◽  
High Level ◽  
Level Resistance

scholarly journals Bacillus thuringiensis and Its Pesticidal Crystal Proteins

1998 ◽  
Vol 62 (3) ◽  
pp. 775-806 ◽  
Author(s):  
E. Schnepf ◽  
N. Crickmore ◽  
J. Van Rie ◽  
D. Lereclus ◽  
J. Baum ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Integrated Management ◽  
Management Strategies ◽  
Resistance Mechanisms ◽  
Maximum Efficiency ◽  
Crystal Proteins ◽  
Evolution Of Resistance ◽  
Complex Relationships ◽  
Bacterium Bacillus ◽  
Natural Settings

SUMMARY During the past decade the pesticidal bacterium Bacillus thuringiensis has been the subject of intensive research. These efforts have yielded considerable data about the complex relationships between the structure, mechanism of action, and genetics of the organism’s pesticidal crystal proteins, and a coherent picture of these relationships is beginning to emerge. Other studies have focused on the ecological role of the B. thuringiensis crystal proteins, their performance in agricultural and other natural settings, and the evolution of resistance mechanisms in target pests. Armed with this knowledge base and with the tools of modern biotechnology, researchers are now reporting promising results in engineering more-useful toxins and formulations, in creating transgenic plants that express pesticidal activity, and in constructing integrated management strategies to insure that these products are utilized with maximum efficiency and benefit.

scholarly journals CRISPR-Mediated Knockout of the ABCC2 Gene in Ostrinia furnacalis Confers High-Level Resistance to the Bacillus thuringiensis Cry1Fa Toxin

Toxins ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 246 ◽  
Author(s):  
Xingliang Wang ◽  
Yanjun Xu ◽  
Jianlei Huang ◽  
Wenzhong Jin ◽  
Yihua Yang ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Deletion Mutation ◽  
Ostrinia Furnacalis ◽  
Corn Borer ◽  
Resistance Evolution ◽  
Loop Region ◽  
Truncating Mutation ◽  
High Level ◽  
Level Resistance

The adoption of transgenic crops expressing Bacillus thuringiensis (Bt) insecticidal crystalline (Cry) proteins has reduced insecticide application, increased yields, and contributed to food safety worldwide. However, the efficacy of transgenic Bt crops is put at risk by the adaptive resistance evolution of target pests. Previous studies indicate that resistance to Bacillus thuringiensis Cry1A and Cry1F toxins was genetically linked with mutations of ATP-binding cassette (ABC) transporter subfamily C gene ABCC2 in at least seven lepidopteran insects. Several strains selected in the laboratory of the Asian corn borer, Ostrinia furnacalis, a destructive pest of corn in Asian Western Pacific countries, developed high levels of resistance to Cry1A and Cry1F toxins. The causality between the O. furnacalis ABCC2 (OfABCC2) gene and resistance to Cry1A and Cry1F toxins remains unknown. Here, we successfully generated a homozygous strain (OfC2-KO) of O. furnacalis with an 8-bp deletion mutation of ABCC2 by the CRISPR/Cas9 approach. The 8-bp deletion mutation results in a frame shift in the open reading frame of transcripts, which produced a predicted protein truncated in the TM4-TM5 loop region. The knockout strain OfC2-KO showed much more than a 300-fold resistance to Cry1Fa, and low levels of resistance to Cry1Ab and Cry1Ac (<10-fold), but no significant effects on the toxicities of Cry1Aa and two chemical insecticides (abamectin and chlorantraniliprole), compared to the background NJ-S strain. Furthermore, we found that the Cry1Fa resistance was autosomal, recessive, and significantly linked with the 8-bp deletion mutation of OfABCC2 in the OfC2-KO strain. In conclusion, in vivo functional investigation demonstrates the causality of the OfABCC2 truncating mutation with high-level resistance to the Cry1Fa toxin in O. furnacalis. Our results suggest that the OfABCC2 protein might be a functional receptor for Cry1Fa and reinforces the association of this gene to the mode of action of the Cry1Fa toxin.

scholarly journals Antimicrobial Resistance of Listeria monocytogenes Strains Isolated from Humans in France

2010 ◽  
Vol 54 (6) ◽  
pp. 2728-2731 ◽  
Author(s):  
A. Morvan ◽  
C. Moubareck ◽  
A. Leclercq ◽  
M. Hervé-Bazin ◽  
S. Bremont ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Antimicrobial Resistance ◽  
Resistant Strain ◽  
Temporal Evolution ◽  
Acquired Resistance ◽  
Mechanisms Of Resistance ◽  
Resistant Strains ◽  
High Level ◽  
Level Resistance ◽  
Microbiological Surveillance

ABSTRACT Susceptibility to antibiotics of 4,816 clinical L. monocytogenes strains isolated since 1926 was studied, and the temporal evolution of susceptibility to antibiotics was analyzed through several decades. The mechanisms of resistance in each resistant strain were studied. The prevalence of resistant strains was estimated at 1.27% among isolates from humans. Resistance to tetracyclines+ and fluoroquinolones was more common and has recently emerged. Although acquired resistance in clinical L. monocytogenes did not implicate clinically relevant antibiotics, the possibility of resistance gene transfers, the description of the first clinical isolate with high-level resistance to trimethoprim, and the recent increase in penicillin MICs up to 2 μg/ml reinforce the need for microbiological surveillance.

scholarly journals Mechanisms of Resistance to Quinupristin-Dalfopristin among Isolates of Enterococcus faecium from Animals, Raw Meat, and Hospital Patients in Western Europe

2000 ◽  
Vol 44 (2) ◽  
pp. 433-436 ◽  
Author(s):  
Mehnam Soltani ◽  
David Beighton ◽  
John Philpott-Howard ◽  
Neil Woodford
Keyword(s):  
Enterococcus Faecium ◽  
Western Europe ◽  
European Countries ◽  
Mechanisms Of Resistance ◽  
Raw Meat ◽  
Hospital Patients ◽  
High Level ◽  
Level Resistance

ABSTRACT Twenty-eight quinupristin-dalfopristin-resistant isolates ofEnterococcus faecium from hospital patients and nonhuman sources in European countries were studied. High-level resistance (MICs, ≥32 μg/ml) was associated with the presence ofvat(E) (satG) (14 isolates [50%]) orvat(D) (satA) (6 isolates [21%]). These genes were not detected in eight (29%) isolates with lower levels of quinupristin-dalfopristin resistance (MICs, 4 to 16 μg/ml). This suggests the presence of further mechanisms of resistance to quinupristin-dalfopristin in E. faecium.

scholarly journals Molecular pathways to high-level azithromycin resistance in Neisseria gonorrhoeae

2020 ◽  
Author(s):  
J.G.E. Laumen ◽  
S.S. Manoharan-Basil ◽  
E Verhoeven ◽  
S Abdellati ◽  
I De Baetselier ◽  
...  
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Ribosomal Proteins ◽  
Efflux Pump ◽  
23S Rrna ◽  
Rrna Gene ◽  
23S Rrna Gene ◽  
Evolution Of Resistance ◽  
High Level ◽  
Azithromycin Resistance ◽  
Level Resistance

AbstractObjectivesThe prevalence of azithromycin resistance in Neisseria gonorrhoeae is increasing in numerous populations worldwide. The aim of this study was to characterize the genetic pathways leading to high-level azithromycin resistance.MethodsA customized morbidostat was used to subject two N. gonorrhoeae reference strains (WHO-F and WHO-X) to dynamically sustained azithromycin pressure. We tracked stepwise evolution of resistance by whole genome sequencing.ResultsWithin 26 days, all cultures evolved high-level azithromycin resistance. Typically, the first step towards resistance was found in transitory mutations in genes rplD, rplV and rpmH (encoding the ribosomal proteins L4, L22 and L34 respectively), followed by mutations in the MtrCDE-encoded efflux pump and the 23S rRNA gene. Low-to high-level resistance was associated with mutations in the ribosomal proteins and MtrCDE-encoded efflux pump. However, high-level resistance was consistently associated with mutations in the 23S ribosomal RNA - mainly the well-known A2059G and C2611T mutations, but also at position A2058G.ConclusionsThis study enabled us to track previously reported mutations and identify novel mutations in ribosomal proteins (L4, L22 and L34) that may play a role in the genesis of azithromycin resistance in N. gonorrhoeae.

High-Level Resistance to Bacillus thuringiensis Toxin Cry1Ac and Cadherin Genotype in Pink Bollworm

2006 ◽  
Vol 99 (6) ◽  
pp. 2125-2131 ◽  
Author(s):  
Bruce E. Tabashnik ◽  
Robert W. Biggs ◽  
Jeffrey A. Fabrick ◽  
Aaron J. Gassmann ◽  
Timothy J. Dennehy ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Pink Bollworm ◽  
High Level ◽  
Level Resistance

scholarly journals Insect resistance management in Bacillus thuringiensis cotton by MGPS (multiple genes pyramiding and silencing)

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Muhammad Mubashar ZAFAR ◽  
Abdul RAZZAQ ◽  
Muhammad Awais FAROOQ ◽  
Abdul REHMAN ◽  
Hina FIRDOUS ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Insect Pests ◽  
Crop Protection ◽  
High Dose ◽  
Bt Cotton ◽  
Artificial Chromosomes ◽  
Cotton Pests ◽  
Multiple Genes ◽  
Bt Toxins ◽  
Evolution Of Resistance

AbstractThe introduction of Bacillus thuringiensis (Bt) cotton has reduced the burden of pests without harming the environment and human health. However, the efficacy of Bt cotton has decreased due to field-evolved resistance in insect pests over time. In this review, we have discussed various factors that facilitate the evolution of resistance in cotton pests. Currently, different strategies like pyramided cotton expressing two or more distinct Bt toxin genes, refuge strategy, releasing of sterile insects, and gene silencing by RNAi are being used to control insect pests. Pyramided cotton has shown resistance against different cotton pests. The multiple genes pyramiding and silencing (MGPS) approach has been proposed for the management of cotton pests. The genome information of cotton pests is necessary for the development of MGPS-based cotton. The expression cassettes against various essential genes involved in defense, detoxification, digestion, and development of cotton pests will successfully obtain favorable agronomic characters for crop protection and production. The MGPS involves the construction of transformable artificial chromosomes, that can express multiple distinct Bt toxins and RNAi to knockdown various essential target genes to control pests. The evolution of resistance in cotton pests will be delayed or blocked by the synergistic action of high dose of Bt toxins and RNAi as well as compliance of refuge requirement.

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