Mechanisms and molecular genetics of insect resistance to insecticidal proteins from Bacillus thuringiensis

Fabrick, Jeffrey A.; Wu, Yidong

doi:10.1016/bs.aiip.2023.09.005

Cited by 11 publications

(2 citation statements)

References 243 publications

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“…Additional work is needed to test the hypothesis that mutations affecting CHS2 reduce binding of Vip3Aa in the larval midgut. This hypothesis is plausible because such reduced binding is the most common and most potent mechanism of insect resistance to Bt toxins [ 51 ]. For the Sfru_R3 strain analyzed here, the lack of strong cross-resistance to Cry1Ab, Cry1Ac, Cry1Fa, and Cry2Ab proteins associated with resistance to Vip3Aa is consistent with a target-specific mechanism rather a more general mechanism that alters processing or penetration of a wide spectrum of insecticidal Bt proteins.…”

Section: Discussionmentioning

confidence: 99%

Retrotransposon-mediated disruption of a chitin synthase gene confers insect resistance to Bacillus thuringiensis Vip3Aa toxin

Liu,

Liao,

Zou

et al. 2024

PLoS Biol

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The vegetative insecticidal protein Vip3Aa from Bacillus thuringiensis (Bt) has been produced by transgenic crops to counter pest resistance to the widely used crystalline (Cry) insecticidal proteins from Bt. To proactively manage pest resistance, there is an urgent need to better understand the genetic basis of resistance to Vip3Aa, which has been largely unknown. We discovered that retrotransposon-mediated alternative splicing of a midgut-specific chitin synthase gene was associated with 5,560-fold resistance to Vip3Aa in a laboratory-selected strain of the fall armyworm, a globally important crop pest. The same mutation in this gene was also detected in a field population. Knockout of this gene via CRISPR/Cas9 caused high levels of resistance to Vip3Aa in fall armyworm and 2 other lepidopteran pests. The insights provided by these results could help to advance monitoring and management of pest resistance to Vip3Aa.

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Section: Discussionmentioning

confidence: 99%

Retrotransposon-mediated disruption of a chitin synthase gene confers insect resistance to Bacillus thuringiensis Vip3Aa toxin

Liu,

Liao,

Zou

et al. 2024

PLoS Biol

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“…Theoretically, any change in this process may lead to a decrease in or even failure of the insecticidal activity of Bt proteins, which decreases the susceptibility to Bt proteins 15 . Alterations in insect midgut receptors, such as cadherins, ATP‐binding cassette (ABC) transporter proteins, alkaline phosphatases and aminopeptidase N, which reduce the binding of these proteins to Bt proteins, are the most common and important resistance mechanisms 10,16–19 …”

Section: Introductionmentioning

confidence: 99%

Mutation in PgABCC2 confers low‐level resistance to Cry1Ac in pink bollworm

Wang,

Xu,

et al. 2024

Pest Management Science

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BackgroundWith the increasing incidence of pest resistance to transgenic crops producing Bacillus thuringiensis (Bt) proteins in the field, elucidating the molecular basis of resistance is important for monitoring, delaying, and countering pest resistance. Previous work revealed that mutation or downregulated expression of the cadherin gene (PgCad1) is associated with pink bollworm (Pectinophora gossypiella) resistance to Cry1Ac, and twenty mutant PgCad1 alleles (r1‐r20) were characterized. Here, we tested the hypothesis that the ABC transporter PgABCC2 is a functional receptor for the Bt toxin Cry1Ac and that a mutation is associated with resistance.ResultsWe identified and characterized the first resistance allele (rC2) of PgABCC2 in the laboratory‐selected Cry1Ac resistant strain AQ‐C2 of pink bollworm. The rC2 allele had a one‐base deletion in exon20, resulting in a frameshift and the introduction of a premature stop codon. This resulting PgABCC2 protein had a truncated C‐terminus, including the loss of the NBD2 domain. AQ‐C2 exhibited 20.2‐fold greater resistance to Cry1Ac than the susceptible strain, and its inheritance of Cry1Ac resistance was recessive and genetically linked to PgABCC2. When produced in cultured insect cells, recombinant wildtype and rC2 mutant PgABCC2 proteins localized within the cell plasma membrane, although substantial cytoplasmic retention was also observed for the mutant protein, while the mutant PgABCC2 caused a 13.9‐fold decrease in Cry1Ac toxicity versus the wildtype PgABCC2.ConclusionsPgABCC2 is a functional receptor of Cry1Ac and the loss of its carboxyl terminus (including its NBD2 domain) confers low‐level resistance to Cry1Ac in both larvae and in cultured cells.

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The role of GPI-anchored membrane-bound alkaline phosphatase in the mode of action of Bt Cry1A toxins in the diamondback moth

Sun,

Xu,

Guo

et al. 2024

Fundamental Research

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Mechanisms and molecular genetics of insect resistance to insecticidal proteins from Bacillus thuringiensis

Cited by 11 publications

References 243 publications

Retrotransposon-mediated disruption of a chitin synthase gene confers insect resistance to Bacillus thuringiensis Vip3Aa toxin

Retrotransposon-mediated disruption of a chitin synthase gene confers insect resistance to Bacillus thuringiensis Vip3Aa toxin

Mutation in PgABCC2 confers low‐level resistance to Cry1Ac in pink bollworm

The role of GPI-anchored membrane-bound alkaline phosphatase in the mode of action of Bt Cry1A toxins in the diamondback moth

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