scholarly journals CRISPR-mediated mutations in the ABC transporter gene ABCA2 confer pink bollworm resistance to Bt toxin Cry2Ab

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jeffrey A. Fabrick ◽  
Dannialle M. LeRoy ◽  
Lolita G. Mathew ◽  
Yidong Wu ◽  
Gopalan C. Unnithan ◽  
...  
Keyword(s):  
Genetic Basis ◽  
Insect Pests ◽  
Pest Resistance ◽  
Genetically Engineered ◽  
Pink Bollworm ◽  
Specific Gene ◽  
Gene Encoding ◽  
Bt Crops ◽  
Bt Toxin ◽  
First Case

AbstractCrops genetically engineered to produce insecticidal proteins from Bacillus thuringiensis (Bt) have many benefits and are important globally for managing insect pests. However, the evolution of pest resistance to Bt crops reduces their benefits. Understanding the genetic basis of such resistance is needed to better monitor, manage, and counter pest resistance to Bt crops. Previous work shows that resistance to Bt toxin Cry2Ab is associated with mutations in the gene encoding the ATP-binding cassette protein ABCA2 in lab- and field-selected populations of the pink bollworm (Pectinophora gossypiella), one of the world’s most destructive pests of cotton. Here we used CRISPR/Cas9 gene editing to test the hypothesis that mutations in the pink bollworm gene encoding ABCA2 (PgABCA2) can cause resistance to Cry2Ab. Consistent with this hypothesis, introduction of disruptive mutations in PgABCA2 in a susceptible strain of pink bollworm increased the frequency of resistance to Cry2Ab and facilitated creation of a Cry2Ab-resistant strain. All Cry2Ab-resistant individuals tested in this study had disruptive mutations in PgABCA2. Overall, we found 17 different disruptive mutations in PgABCA2 gDNA and 26 in PgABCA2 cDNA, including novel mutations corresponding precisely to single-guide (sgRNA) sites used for CRISPR/Cas9. Together with previous results, these findings provide the first case of practical resistance to Cry2Ab where evidence identifies a specific gene in which disruptive mutations can cause resistance and are associated with resistance in field-selected populations.

scholarly journals Genetically Modified Potato for Pest Resistance: Thrift or Threat?

2021 ◽  
Author(s):  
Martin Raspor ◽  
Aleksandar Cingel
Keyword(s):  
Insect Pests ◽  
Genetically Modified ◽  
New Technology ◽  
Single Gene ◽  
Genetically Modified Crops ◽  
Pest Resistance ◽  
Potato Production ◽  
Bt Toxin ◽  
Long Term Impact ◽  
The Cost

Significant limitations in potato production are crop loss due to the damage made by insect pests, and the cost of enormous amount of chemicals, harmful to humans and environment, extensively used in their control. As an alternative, development of genetically modified potato offered possibility for pest management in a more sustainable, environmentally friendly way. Over the past 30 years introduction of pest resistance traits progressed from a single gene to multiple stacked events and from Bt-toxin expression to expression of proteins from non-Bt sources, dsRNA and their combination, while advances in molecular biology have brought “cleaner” gene manipulation technologies. However, together with benefits any new technology also bears its risks, and there are still a range of unanswered questions and concerns about long-term impact of genetically modified crops – that with knowledge and precautionary approaches can be avoided or mitigated. Sustainability of genetically modified crops for pest control largely depends on the willingness to gain and implement such knowledge.

scholarly journals Hybridizing transgenic Bt cotton with non-Bt cotton counters resistance in pink bollworm

2017 ◽  
Vol 114 (21) ◽  
pp. 5413-5418 ◽  
Author(s):  
Peng Wan ◽  
Dong Xu ◽  
Shengbo Cong ◽  
Yuying Jiang ◽  
Yunxin Huang ◽  
...  
Keyword(s):  
First Generation ◽  
Resistance Management ◽  
Genetically Engineered ◽  
Pink Bollworm ◽  
Bt Cotton ◽  
Bt Toxin ◽  
Random Mixture ◽  
Cotton Plants ◽  
Evolution Of Resistance ◽  
Insecticide Sprays

Extensive cultivation of crops genetically engineered to produce insecticidal proteins from the bacteriumBacillus thuringiensis(Bt) has suppressed some major pests, reduced insecticide sprays, enhanced pest control by natural enemies, and increased grower profits. However, these benefits are being eroded by evolution of resistance in pests. We report a strategy for combating resistance by crossing transgenic Bt plants with conventional non-Bt plants and then crossing the resulting first-generation (F1) hybrid progeny and sowing the second-generation (F2) seeds. This strategy yields a random mixture within fields of three-quarters of plants that produce Bt toxin and one-quarter that does not. We hypothesized that the non-Bt plants in this mixture promote survival of susceptible insects, thereby delaying evolution of resistance. To test this hypothesis, we compared predictions from computer modeling with data monitoring pink bollworm (Pectinophora gossypiella) resistance to Bt toxin Cry1Ac produced by transgenic cotton in an 11-y study at 17 field sites in six provinces of China. The frequency of resistant individuals in the field increased before this strategy was widely deployed and then declined after its widespread adoption boosted the percentage of non-Bt cotton plants in the region. The correspondence between the predicted and observed outcomes implies that this strategy countered evolution of resistance. Despite the increased percentage of non-Bt cotton, suppression of pink bollworm was sustained. Unlike other resistance management tactics that require regulatory intervention, growers adopted this strategy voluntarily, apparently because of advantages that may include better performance as well as lower costs for seeds and insecticides.

scholarly journals Pink Bollworm Resistance to Bt Toxin Cry1Ac Associated with an Insertion in Cadherin Exon 20

Toxins ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 186 ◽  
Author(s):  
Ling Wang ◽  
Yuemin Ma ◽  
Xueqin Guo ◽  
Peng Wan ◽  
Kaiyu Liu ◽  
...  
Keyword(s):  
Insect Pests ◽  
Stop Codon ◽  
Premature Stop Codon ◽  
Pink Bollworm ◽  
Cross Resistance ◽  
Bt Cotton ◽  
Wild Type ◽  
Bt Toxin ◽  
Exon 20 ◽  
In Cells

Insecticidal proteins from Bacillus thuringiensis (Bt) are widely used to control insect pests, but their efficacy is reduced when pests evolve resistance. We report on a novel allele (r16) of the cadherin gene (PgCad1) in pink bollworm (Pectinophora gossypiella) associated with resistance to Bt toxin Cry1Ac, which is produced by transgenic cotton. The r16 allele isolated from a field population in China has 1545 base pairs of a degenerate transposon inserted in exon 20 of PgCad1, which generates a mis-spliced transcript containing a premature stop codon. A strain homozygous for r16 had 300-fold resistance to Cry1Ac, 2.6-fold cross-resistance to Cry2Ab, and completed its life cycle on transgenic Bt cotton producing Cry1Ac. Inheritance of Cry1Ac resistance was recessive and tightly linked with r16. Compared with transfected insect cells expressing wild-type PgCad1, cells expressing r16 were less susceptible to Cry1Ac. Recombinant cadherin protein was transported to the cell membrane in cells transfected with the wild-type PgCad1 allele, but not in cells transfected with r16. Cadherin occurred on brush border membrane vesicles (BBMVs) in the midgut of susceptible larvae, but not resistant larvae. These results imply that the r16 allele mediates Cry1Ac resistance in pink bollworm by interfering with the localization of cadherin.

scholarly journals Shared and Independent Genetic Basis of Resistance to Bt Toxin Cry2Ab in Two Strains of Pink Bollworm

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jeffrey A. Fabrick ◽  
Dannialle M. LeRoy ◽  
Gopalan C. Unnithan ◽  
Alex J. Yelich ◽  
Yves Carrière ◽  
...  
Keyword(s):  
Genetic Basis ◽  
Pink Bollworm ◽  
Bt Toxin

The contribution of animal models to the study of obesity

2008 ◽  
Vol 42 (4) ◽  
pp. 413-432 ◽  
Author(s):  
John Speakman ◽  
Catherine Hambly ◽  
Sharon Mitchell ◽  
Elżbieta Król
Keyword(s):  
Energy Balance ◽  
Animal Models ◽  
Genetic Basis ◽  
Single Gene ◽  
Genetically Engineered ◽  
Specific Gene ◽  
Entire Body ◽  
High Fat ◽  
Random Mutation ◽  
The Impact

Summary Obesity results from prolonged imbalance of energy intake and energy expenditure. Animal models have provided a fundamental contribution to the historical development of understanding the basic parameters that regulate the components of our energy balance. Five different types of animal model have been employed in the study of the physiological and genetic basis of obesity. The first models reflect single gene mutations that have arisen spontaneously in rodent colonies and have subsequently been characterized. The second approach is to speed up the random mutation rate artificially by treating rodents with mutagens or exposing them to radiation. The third type of models are mice and rats where a specific gene has been disrupted or overexpressed as a deliberate act. Such genetically-engineered disruptions may be generated through the entire body for the entire life (global transgenic manipulations) or restricted in both time and to certain tissue or cell types. In all these genetically-engineered scenarios, there are two types of situation that lead to insights: where a specific gene hypothesized to play a role in the regulation of energy balance is targeted, and where a gene is disrupted for a different purpose, but the consequence is an unexpected obese or lean phenotype. A fourth group of animal models concern experiments where selective breeding has been utilized to derive strains of rodents that differ in their degree of fatness. Finally, studies have been made of other species including non-human primates and dogs. In addition to studies of the physiological and genetic basis of obesity, studies of animal models have also informed us about the environmental aspects of the condition. Studies in this context include exploring the responses of animals to high fat or high fat/high sugar (Cafeteria) diets, investigations of the effects of dietary restriction on body mass and fat loss, and studies of the impact of candidate pharmaceuticals on components of energy balance. Despite all this work, there are many gaps in our understanding of how body composition and energy storage are regulated, and a continuing need for the development of pharmaceuticals to treat obesity. Accordingly, reductions in the use of animal models, while ethically desirable, will not be feasible in the short to medium term, and indeed an expansion in activity using animal models is anticipated as the epidemic continues and spreads geographically.

Global Patterns of Resistance to Bt Crops Highlighting Pink Bollworm in the United States, China, and India

2019 ◽  
Vol 112 (6) ◽  
pp. 2513-2523 ◽  
Author(s):  
Bruce E Tabashnik ◽  
Yves Carrière
Keyword(s):  
United States ◽  
Pest Control ◽  
Crop Residues ◽  
The United States ◽  
Economic Benefits ◽  
Genetically Engineered ◽  
Pink Bollworm ◽  
Bt Cotton ◽  
Pest Species ◽  
Bt Crops

Abstract Crops genetically engineered to produce insecticidal proteins from Bacillus thuringiensis (Bt) have advanced pest control, but their benefits have been reduced by evolution of resistance in pests. The global monitoring data reviewed here reveal 19 cases of practical resistance to Bt crops, which is field-evolved resistance that reduces Bt crop efficacy and has practical consequences for pest control. Each case represents the responses of one pest species in one country to one Bt toxin. The results with pink bollworm (Pectinophora gossypiella) and Bt cotton differ strikingly among the world’s three leading cotton-producing nations. In the southwestern United States, farmers delayed resistance by planting non-Bt cotton refuges from 1996 to 2005, then cooperated in a program that used Bt cotton, mass releases of sterile moths, and other tactics to eradicate this pest from the region. In China, farmers reversed low levels of pink bollworm resistance to Bt cotton by planting second-generation hybrid seeds from crosses between Bt and non-Bt cotton. This approach yields a refuge of 25% non-Bt cotton plants randomly interspersed within fields of Bt cotton. Farmers adopted this tactic voluntarily and unknowingly, not to manage resistance, but apparently because of its perceived short-term agronomic and economic benefits. In India, where non-Bt cotton refuges have been scarce and pink bollworm resistance to pyramided Bt cotton producing Cry1Ac and Cry2Ab toxins is widespread, integrated pest management emphasizing shortening of the cotton season, destruction of crop residues, and other tactics is now essential.

scholarly journals Novel genetic basis of resistance to Bt toxin Cry1Ac in Helicoverpa zea

2021 ◽  
Author(s):  
Kyle M Benowitz ◽  
Carson W Allan ◽  
Benjamin A Degain ◽  
Xianchun Li ◽  
Jeffrey A Fabrick ◽  
...  
Keyword(s):  
Helicoverpa Zea ◽  
Genetic Basis ◽  
Stop Codon ◽  
Premature Stop Codon ◽  
Pest Resistance ◽  
The United States ◽  
Chromosome 13 ◽  
Bt Toxin ◽  
Bt Toxins ◽  
A Genome

Crops genetically engineered to produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) have advanced pest management, but their benefits are diminished when pests evolve resistance. Elucidating the genetic basis of pest resistance to Bt toxins can improve resistance monitoring, resistance management, and design of new insecticides. Here, we investigated the genetic basis of resistance to Bt toxin Cry1Ac in the lepidopteran Helicoverpa zea, one of the most damaging crop pests in the United States. To facilitate this research, we built the first chromosome-level genome assembly for this species. Using a genome-wide association study, fine-scale mapping, and RNA-seq, we identified a 250kb QTL on chromosome 13 that was strongly associated with resistance in a strain of H. zea that had been selected for resistance in the field and lab. This QTL contains no genes with a previously reported role in resistance or susceptibility to Bt toxins. However, within this QTL, we discovered a premature stop codon in a kinesin gene. We hypothesize that this mutation contributes to resistance. The results indicate the mutation on chromosome 13 was necessary but not sufficient for resistance, and therefore conclude that mutations in more than one gene contributed to resistance. Moreover, we found no changes in gene sequence or expression consistently associated with resistance for 11 genes previously implicated in lepidopteran resistance to Cry1Ac. Thus, the results reveal a novel and polygenic basis of resistance and extend the list of genes contributing to pest resistance to Bt toxins.

Shared Genetic Basis of Resistance to Bt Toxin Cry1Ac in Independent Strains of Pink Bollworm

2004 ◽  
Vol 97 (3) ◽  
pp. 721-726 ◽  
Author(s):  
Bruce E. Tabashnik ◽  
Yong-Biao Liu ◽  
Devika C. Unnithan ◽  
Yves Carrière ◽  
Timothy J. Dennehy ◽  
...  
Keyword(s):  
Genetic Basis ◽  
Pink Bollworm ◽  
Bt Toxin ◽  
Shared Genetic
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