Intra- and extracellular domains of the Helicoverpa armigera cadherin mediate Cry1Ac cytotoxicity

Zhang, Haonan; Yu, Shan; Shi, Yu; Yang, Yihua; Fabrick, Jeffrey A.; Wu, Yi

doi:10.1016/j.ibmb.2017.05.004

Cited by 22 publications

(31 citation statements)

References 40 publications

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“…The red line shows the putative toxin‐binding region of HaCad. No mutations were found in SCD or LF256 in amino acids 1,422–1,440, which are especially important in binding (Zhang et al., )…”

Section: Resultsmentioning

confidence: 99%

Epistasis confers resistance to Bt toxin Cry1Ac in the cotton bollworm

Gao

Wang

Yang

et al. 2018

Evolutionary Applications

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Evolution of resistance by insect pests reduces the benefits of extensively cultivated transgenic crops that produce insecticidal proteins from Bacillus thuringiensis (Bt).Previous work showed that resistance to Bt toxin Cry1Ac, which is produced by transgenic cotton, can be conferred by mutations disrupting a cadherin protein that binds this Bt toxin in the larval midgut. However, the potential for epistatic interactions between the cadherin gene and other genes has received little attention. Here, we report evidence of epistasis conferring resistance to Cry1Ac in the cotton bollworm, Helicoverpa armigera, one of the world's most devastating crop pests. Resistance to Cry1Ac in strain LF256 originated from a field-captured male and was autosomal, recessive, and 220-fold relative to susceptible strain SCD. We conducted complementation tests for allelism by crossing LF256 with a strain in which resistance to Cry1Ac is conferred by a recessive allele at the cadherin locus HaCad. The resulting F 1 offspring were resistant, suggesting that resistance to Cry1Ac in LF256 is also conferred by resistance alleles at this locus. However, the HaCad amino acid sequence in LF256 lacked insertions and deletions, and did not differ consistently between LF256 and a susceptible strain. In addition, most of the cadherin alleles in LF256 were not derived from the field-captured male. Moreover, Cry1Ac resistance was not genetically linked with the HaCad locus in LF256. Furthermore, LF256 and the susceptible strain were similar in levels of HaCad transcript, cadherin protein, and binding of Cry1Ac to cadherin. Overall, the results imply that epistasis between HaCad and an unknown second locus in LF256 yielded the observed resistance in the F 1 progeny from the complementation test. The observed epistasis has important implications for interpreting results of the F 1 screen used widely to monitor and analyze resistance, as well as the potential to accelerate evolution of resistance. K E Y W O R D Sallelism, Bacillus thuringiensis, cotton bollworm, F 1 screen, genetically engineered crop, resistance management, second-site noncomplementation, transgenic cotton

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Section: Resultsmentioning

confidence: 99%

Epistasis confers resistance to Bt toxin Cry1Ac in the cotton bollworm

Gao

Wang

Yang

et al. 2018

Evolutionary Applications

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“… Sequence Helicoverpa armigera (LOC 110371604) is a predicted cadherin-related tumor suppressor; sequence Helicoverpa armigera (BtR) (AY647974) is annotated as in [ 121 ], and additional information [ 127 , 128 ]; sequence Manduca sexta (BT-R1) (AF319973) is annotated as in [ 122 ]. EC = cadherin repeats (in red); TBR = putative Cry1Ac toxin binding region (in blue).…”

Section: Supporting Informationmentioning

confidence: 99%

Loci under selection and markers associated with host plant and host-related strains shape the genetic structure of Brazilian populations of Spodoptera frugiperda (Lepidoptera, Noctuidae)

et al. 2018

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We applied the ddRAD genotyping-by-sequencing technique to investigate the genetic distinctiveness of Brazilian populations of the noctuid moth Spodoptera frugiperda, the fall armyworm (FAW), and the role of host-plant association as a source of genetic diversification. By strain-genotyping all field-collected individuals we found that populations collected from corn were composed primarily of corn-strain individuals, while the population collected from rice was composed almost entirely of rice-strain individuals. Outlier analyses indicated 1,184 loci putatively under selection (ca. 15% of the total) related to 194 different Gene Ontologies (GOs); the most numerous GOs were nucleotide binding, ATP binding, metal-ion binding and nucleic-acid binding. The association analyses indicated 326 loci associated with the host plant, and 216 loci associated with the individual strain, including functions related to Bacillus thuringiensis and insecticide resistance. The genetic-structure analyses indicated a moderate level of differentiation among all populations, and lower genetic structure among populations collected exclusively from corn, which suggests that the population collected from rice has a strong influence on the overall genetic structure. Populations of S. frugiperda are structured partially due to the host plant, and pairs of populations using the same host plant are more genetically similar than pairs using different hosts. Loci putatively under selection are the main factors responsible for the genetic structure of these populations, which indicates that adaptive selection on important traits, including the response to control tactics, is acting in the genetic differentiation of FAW populations in Brazil.

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“…Binding of a Cry toxin to the toxin binding region (TBR) on a cadherin receptor is required for further toxin cleavage, oligomerization and eventual pore-forming that is critical for intoxication [18]. Presently a number of cadherin mutations have been identified and some confer resistance to the Cry toxins in Heliothis virescens, Pectinophora gossypiella and Helicoverpa armigera [6,19,20]. Moreover, homozygous knockout of the cadherin gene in H. armigera confers resistance to the Cry1Ac toxin [21].…”

Section: Introductionmentioning

confidence: 99%

Aedes cadherin receptor that mediates Bacillus thuringiensis Cry11A toxicity is essential for mosquito development

2020

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Aedes cadherin (AaeCad, AAEL024535) has been characterized as a receptor for Bacillus thuringiensis subsp. israelensis (Bti) Cry11A toxins. However, its role in development is still unknown. In this study, we modified the cadherin gene using ZFN and TALEN. Even though we obtained heterozygous deletions, no homozygous mutants were viable. Because ZFN and TALEN have lower off-targets than CRISPR/Cas9, we conclude the cadherin gene is essential for Aedes development. In contrast, in lepidopteran insects loss of a homologous cadherin does not appear to be lethal, since homozygous mutants are viable. To analyze the role of AaeCad in vivo, we tagged this protein with EGFP using CRISPR-Cas9-mediated homologous recombination and obtained a homozygous AaeCad-EGFP line. Addition of Aedes Rad51 mRNA enhanced the rate of recombination. We then examined AaeCad protein expression in most tissues and protein dynamics during mosquito development. We observe that AaeCad is expressed in larval and adult midgut-specific manner and its expression pattern changed during the mosquito development. Confocal images showed AaeCad has high expression in larval caecae and posterior midgut, and also in adult midgut. Expression of AaeCad is observed primarily in the apical membranes of epithelial cells, and not in cell-cell junctions. The expression pattern observed suggests AaeCad does not appear to play a role in these junctions. However, we cannot exclude its role beyond cell-cell adhesion in the midgut. We also observed that Cry11A bound to the apical side of larval gastric caecae and posterior midgut cells exactly where AaeCad-EGFP was expressed. Their co-localization suggests that AaeCad is indeed a receptor for the Cry11A toxin. Using this mosquito line we also observed that low doses of Cry11A toxin caused the cells to slough off membranes, which likely represents a defense mechanism, to limit cell damage from Cry11A toxin pores formed in the cell membrane.

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Intra- and extracellular domains of the Helicoverpa armigera cadherin mediate Cry1Ac cytotoxicity

Cited by 22 publications

References 40 publications

Epistasis confers resistance to Bt toxin Cry1Ac in the cotton bollworm

Epistasis confers resistance to Bt toxin Cry1Ac in the cotton bollworm

Loci under selection and markers associated with host plant and host-related strains shape the genetic structure of Brazilian populations of Spodoptera frugiperda (Lepidoptera, Noctuidae)

Aedes cadherin receptor that mediates Bacillus thuringiensis Cry11A toxicity is essential for mosquito development

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