Diverse genetic basis of <scp>Vip3Aa</scp> resistance in five independent field‐derived strains of <scp><i>Helicoverpa zea</i></scp> in the US

Yang, Fei; Head, Graham P; Kerns, Dawson D; Jurat‐Fuentes, Juan Luis; Santiago‐González, José C; Kerns, David L

doi:10.1002/ps.7988

Cited by 3 publications

(1 citation statement)

References 59 publications

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“…Related work with 5 laboratory-selected strains of H . zea from the southern US highly resistant to Vip3Aa also shows variation among strains in the genetic basis of resistance [ 58 ]. Although the specific genes conferring resistance to Vip3Aa were not identified, interstrain complementation tests revealed 3 distinct genetic loci involved, with 1 locus implicated in 2 strains derived from the same field collection, a second locus implicated in 2 other strains from field collections in different states, and the third locus involved in just 1 strain [ 58 ].…”

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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Continued decline in sublethal effects of Bt toxins on Helicoverpa zea (Lepidoptera: Noctuidae) in field corn

Bryant,

Greene,

Reisig

et al. 2024

Journal of Economic Entomology

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The majority of field corn, Zea mays L., in the southeastern United States has been genetically engineered to express insecticidal toxins produced by the soil bacterium, Bacillus thuringiensis (Bt). Field corn is the most important mid-season host for corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), which has developed resistance to all Cry toxins in Bt corn. From 2020 to 2023, corn earworm pupae were collected from early- and late-planted pyramided hybrids expressing Bt toxins and non-Bt near-isolines in North and South Carolina (16 trials). A total of 5,856 pupae were collected across all trials, with 55 and 88% more pupae collected in later-planted trials relative to early plantings in North and South Carolina, respectively. Only 20 pupae were collected from hybrids expressing Cry1F + Cry1Ab + Vip3A20 across all trials. Averaged across trials, Cry1A.105 + Cry2Ab2 hybrids reduced pupal weight by 6 and 9% in North and South Carolina, respectively, relative to the non-Bt near-isoline. Cry1F + Cry1Ab hybrids reduced pupal weight on average by 3 and 8% in North and South Carolina, respectively, relative to the non-Bt near-isoline. The impact of the Bt toxins on pupal weight varied among trials. When combined with data from 2014 to 2019 from previous studies, a significant decline in the percent reduction in pupal weight over time was found in both states and hybrid families. This study demonstrates a continued decline in the sublethal impacts of Bt toxins on corn earworm, emphasizing the importance of insect resistance management practices.

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Knockout of theSfVipR1gene confers high-level resistance toBacillus thuringiensisVip3Aa toxin inSpodoptera frugiperda

Zhang,

Wang,

Pang

et al. 2024

Preprint

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Background: Bacillus thuringiensis (Bt) insecticidal proteins, including Cry proteins and vegetative insecticidal proteins (Vips), are extensively utilized in transgenic crops due to their efficacy and safety. The fall armyworm, Spodoptera frugiperda, has evolved practical resistance to Cry1Fa, yet no practical resistance to Vip3Aa has been documented. However, both laboratory selection and field screen studies indicate a high potential for this pest to evolve resistance to Vip3Aa, making it crucial to evaluate potential resistance genes. HaVipR1 has recently been identified as a key determinant of Vip3Aa resistance in the cotton bollworm, Helicoverpa armigera. This study investigated whether the HaVipR1-homologous gene in S. frugiperda (SfVipR1) is similarly involved in Vip3Aa resistance. Results: We employed CRISPR/Cas9 technology to generate a homozygous knockout strain of SfVipR1. In comparison with the parent susceptible YJ-19 strain, the knockout strain (Sfru-KO) exhibited high-level resistance to Vip3Aa (>1875-fold) but showed no resistance to Cry1Fa. This acquired resistance to Vip3Aa is autosomal, recessive, and genetically linked to the deletion mutation in SfVipR1 within the Sfru-KO strain of S. frugiperda. Conclusion: Disruption of SfVipR1 results in high-level resistance to Vip3Aa, highlighting SfVipR1 has a critical role in Vip3Aa toxicity in S. frugiperda, despite the exact mechanism remaining unclear. Early detection of SfVipR1 mutant alleles in the field is essential for developing adaptive resistance management strategies against S. frugiperda.

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Diverse genetic basis of Vip3Aa resistance in five independent field‐derived strains of Helicoverpa zea in the US

Cited by 3 publications

References 59 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

Continued decline in sublethal effects of Bt toxins on Helicoverpa zea (Lepidoptera: Noctuidae) in field corn

Knockout of theSfVipR1gene confers high-level resistance toBacillus thuringiensisVip3Aa toxin inSpodoptera frugiperda

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