Genotype‐specific fitness cost of resistance to Bt toxin Cry1Ac in pink bollworm

Carrière, Yves; Williams, Jennifer L.; Crowder, David W.; Tabashnik, Bruce E.

doi:10.1002/ps.4928

Cited by 11 publications

(8 citation statements)

References 56 publications

(197 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, the observed number of 19 r1r1 individuals is 79 times higher than the expected number ( P < 0.0001, Fisher's exact test), which implies strong selection favoring this allele. However, in an analysis of allele trajectories in heterogeneous strains from the U.S. reared on untreated diet, the fitness cost was not lower for r1 than r2 or r3 . This result does not support the hypothesis of a relatively low fitness cost in the absence of Cry1Ac contributing to the higher frequency of r1 .…”

Section: Discussionmentioning

confidence: 63%

“…In India, however, this pest evolved practical resistance to Bt cotton producing Cry1Ac alone, then to dual‐toxin Bt cotton producing Cry1Ac and Cry2Ab . In the U.S. and China, pink bollworm has not evolved practical resistance to Cry1Ac in the field, but laboratory selection of insects from each country has yielded many strains resistant to Cry1Ac, indicating the potential for field‐evolved resistance.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Bt resistance alleles in field populations of pink bollworm from China: Similarities with the United States and decreased frequency from 2012 to 2015

Wang

Cong

et al. 2019

Pest Management Science

Self Cite

View full text Add to dashboard Cite

BACKGROUND: Although most monitoring of pest resistance to widely cultivated transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt) relies on bioassays, DNA screening for alleles associated with resistance has some advantages, particularly for rare, recessively inherited resistance. In China's Yangtze River Valley, where farmers first planted transgenic cotton producing Bt toxin Cry1Ac in 2000, bioassays have been used to monitor the recessive resistance of pink bollworm (Pectinophora gossypiella). Previous bioassay results show a small but significant increase in resistance to Cry1Ac during 2008-2010, followed by a significant decrease in resistance during 2011-2015 associated with extensive planting of second-generation hybrid cotton seeds that boosted the percentage of non-Bt cotton. Here we screened DNA from 19 748 pink bollworm collected during 2012-2015 from the Yangtze River Valley for seven alleles associated with resistance to Cry1Ac. These alleles were previously identified from lab-selected strains; three from the U.S. and four from China. RESULTS: The most common resistance allele was first identified from the U.S. and accounted for over 71% of all resistance alleles detected. Resistance was rare, with the total frequency of the seven resistance alleles showing a significant, 2.3-fold decrease from 0.0105 (95% CI: 0.0084-0.0132) in 2012 to 0.0046 (0.0031-0.0067) in 2015. CONCLUSIONS: The DNA screening data confirm results from bioassays showing pink bollworm resistance to Cry1Ac remained rare in the Yangtze River Valley from 2012-2015. The prevalence in China of the resistance allele identified from the U.S. implies a shared genetic basis of resistance that could facilitate molecular monitoring of resistance.

show abstract

Section: Discussionmentioning

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Bt resistance alleles in field populations of pink bollworm from China: Similarities with the United States and decreased frequency from 2012 to 2015

Wang

Cong

et al. 2019

Pest Management Science

Self Cite

View full text Add to dashboard Cite

show abstract

“…AZP‐R, derived from 10 populations collected in Arizona cotton fields in 1997, has 1500‐3100‐fold resistance to Cry1Ac originally conferred by three cadherin alleles named r 1 , r 2 and r 3 . Whereas all three cadherin alleles were initially present in AZP‐R, only the r2 allele currently exists in this strain due to fitness costs associated with the r1 and r3 alleles and continuous long‐term laboratory rearing . APHIS‐R is a new strain derived by the mass selection of APHIS‐S on diet containing a discriminating concentration of Cry1Ac (10 μg per mL diet) in October 2017.…”

Section: Methodsmentioning

confidence: 99%

“…37,45,46 Whereas all three cadherin alleles were initially present in AZP-R, only the r2 allele currently exists in this strain due to fitness costs associated with the r1 and r3 alleles and continuous long-term laboratory rearing. 47 APHIS-R is a new strain derived by the mass selection of APHIS-S on diet containing a discriminating concentration of Cry1Ac (10 μg per mL diet) in October 2017. Survivors from the initial selection (∼200 rr pupae) were pooled and maintained on laboratory diet in environmental chambers under standard rearing conditions (26 ∘ C; 14:10 light:dark photoperiod).…”

Section: Insect Strains and Rearingmentioning

confidence: 99%

Reduced cadherin expression associated with resistance to Bt toxin Cry1Ac in pink bollworm

Fabrick

Mathew

LeRoy

et al. 2019

Pest Management Science

Self Cite

View full text Add to dashboard Cite

BACKGROUND Better understanding of the molecular basis of resistance is needed to improve management of pest resistance to transgenic crops that produce insecticidal proteins from Bacillus thuringiensis (Bt). Here we analyzed resistance of the pink bollworm (Pectinophora gossypiella) to Bt toxin Cry1Ac, which is used widely in transgenic Bt cotton. Field‐evolved practical resistance of pink bollworm to Cry1Ac is widespread in India, but not in China or the United States. Previous work with laboratory‐ and field‐selected pink bollworm indicated that resistance to Cry1Ac is caused by changes in the amino acid sequence of a midgut cadherin protein (PgCad1) that binds Cry1Ac in susceptible larvae. RESULTS Relative to a susceptible strain, the laboratory‐selected APHIS‐R strain had 530‐fold resistance to Cry1Ac with autosomal recessive inheritance. Unlike previous results, resistance in this strain was not consistently associated with insertions or deletions in the expected amino acid sequence of PgCad1. However, this resistance was associated with 79‐ to 190‐fold reduced transcription of the PgCad1 gene and markedly lower abundance of PgCad1 protein. CONCLUSION The ability of pink bollworm and other major pests to evolve resistance to Bt toxins via both qualitative and quantitative changes in receptor proteins demonstrates their remarkable adaptability and presents challenges for monitoring and managing resistance to Bt crops. © 2019 Society of Chemical Industry

show abstract

“…For example, genes in our putative sweep regions may allow for recovery of fitness in individuals bearing mutations with otherwise deleterious effects. Many insecticide resistance mutations are thought to negatively impact fitness in the absence of insecticide pressure (Kliot and Ghanim, 2012), and Bt resistance mutations are no exception (Gassmann et al, 2009; Carrière et al, 2018b). Perhaps selection for a mutation that conferred resistance in GA-R was followed by selection for mutations that improve the fitness of individuals bearing such a mutation.…”

Section: Discussionmentioning

confidence: 99%

Mutations in a novel cadherin gene associated with Bt resistance in Helicoverpa zea

Fritz

Nunziata

Guo

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

20Transgenic corn and cotton produce crystalline (Cry) proteins derived from the soil 21 bacterium Bacillus thuringiensis (Bt) that are toxic to lepidopteran larvae. Helicoverpa zea, a 22 key pest of corn and cotton in the U.S., has evolved widespread resistance to these proteins 23 produced in Bt corn and cotton. While the genomic targets of Cry selection and the mutations 24 that produce resistant phenotypes are known in other lepidopteran species, little is known about 25 how Cry proteins shape the genome of H. zea. We scanned the genomes of Cry1Ac-selected and 26 unselected H. zea lines, and identified eleven genes on six scaffolds that showed evidence of 27 selection by Cry1Ac, including cadherin-86C (cad-86C), a gene from a family that is involved in 28 Cry1A resistance in other lepidopterans. Although this gene was expressed in the H. zea larval 29 midgut, the protein it encodes has only 17 to 22% identity with cadherin proteins from other 30 species previously reported to be involved in Bt resistance. An analysis of midgut-expressed 31 cDNAs showed significant between-line differences in the frequencies of putative 32 nonsynonymous substitutions (both SNPs and indels). Our results indicate that cad-86C is a 33 target of Cry1Ac selection in H. zea. Future work should investigate phenotypic effects of these 34 nonsynonymous substitutions and their impact on phenotypic resistance in field populations.

show abstract

Genotype‐specific fitness cost of resistance to Bt toxin Cry1Ac in pink bollworm

Cited by 11 publications

References 56 publications

Bt resistance alleles in field populations of pink bollworm from China: Similarities with the United States and decreased frequency from 2012 to 2015

Bt resistance alleles in field populations of pink bollworm from China: Similarities with the United States and decreased frequency from 2012 to 2015

Reduced cadherin expression associated with resistance to Bt toxin Cry1Ac in pink bollworm

Mutations in a novel cadherin gene associated with Bt resistance in Helicoverpa zea

Contact Info

Product

Resources

About