Biology subjects

Bachler, A.

Publications and source records attributed to Bachler, A..

3 recordsLinked to original sources

bioRxiv2026

Transposable element disruption of a second thyroglobulin-like gene confers Vip3Aa resistance in Helicoverpa armigera

BackgroundThe cotton bollworm Helicoverpa armigera is a major global pest controlled by genetically engineered crops expressing Bacillus thuringiensis (Bt) toxins, including Vip3Aa. While Vip3Aa is widely deployed, the genetic basis of resistance remains poorly understood. Previous work identified disruption of a thyroglobulin-like gene (HaVipR1) as one mechanism of resistance, suggesting additional loci may be involved. ResultsUsing linkage analysis, transcriptomics, long-read sequencing, and CRISPR-Cas9 gene editing, we identify a second thyroglobulin-like gene, HaVipR2, as a novel mediator of Vip3Aa resistance. Resistance in a field-derived H. armigera line was shown to be monogenic, recessive, and autosomal, mapping to chromosome 29. Long-read sequencing revealed a [~]16 kb transposable element insertion disrupting HaVipR2, which was undetectable using standard short-read approaches. CRISPR-Cas9 knockout of HaVipR2 conferred >900-fold resistance, confirming its causal role. Comparative analyses show that HaVipR1 and HaVipR2 share conserved domain architecture, indicating that thyroglobulin-domain proteins represent a recurrent target of resistance evolution. ConclusionsOur findings establish thyroglobulin-domain proteins as a new class of Bt resistance genes in Lepidoptera and demonstrate that transposable element insertions can drive adaptive resistance while evading detection by conventional methods. These results highlight the importance of long-read sequencing and accurate genome annotation for resistance monitoring and provide new insights into the molecular basis and evolution of Vip3Aa resistance.

genomics↗

bioRxiv2026

Genomic repeatability and predictability of local (mal)adaptation in a reef-building coral

Climate change is a growing threat to biodiversity, and the persistence of populations largely depends on their capacity to adapt to changing environmental conditions. Although there is an urgent need to forecast local adaptive potential, it is unclear how such predictions are affected by the genomic architectures underlying local adaptation across a species range. In this study, we examine the genomic basis of local adaptation of the short-distance dispersing coral Stylophora pistillata, sampled at forty-six sites across eight reefs of the Great Barrier Reef, Australia. Our results show that thermal adaptation for this species involves hundreds of genomic loci with combinations that differ across geographic regions. Although adaptive loci were largely region-specific, genotype-environment relationships estimated across the entire range could predict regional-level adaptive patterns. This shows that genome-wide sequence data combined with geographically broad sampling can support reliable evolutionary forecasting. Under climate change projections, predicted shifts in genotype-environment associations were highly spatially variable, both between and within geographic regions. While some populations might be sufficiently adapted for moderate (SSP1-2.6 and SSP2-4.5) climate warming by 2050, up to 30% may face severe maladaptation risk by 2100 under a high-emission (SSP5-8.5) scenario. Collectively, these findings offer new insights into the spatial distribution of coral adaptive potential and how it might shape corals resilience in a warming ocean.

evolutionary biology↗

bioRxiv2024

Identification of a novel resistance gene which provides insight into Vip3Aa mode of action in Helicoverpa armigera

The global reliance on Bacillus thuringiensis (Bt) proteins for controlling lepidopteran pests in cotton, corn, and soybean crops underscores the critical need to understand resistance mechanisms. Vip3Aa, one of the most widely deployed and currently effective Bt proteins in genetically modified crops, plays a pivotal role in pest management. This study identifies the molecular basis of Vip3Aa resistance in Australian Helicoverpa armigera through genetic crosses, and integrated genomic and transcriptomic analyses. We identified a previously uncharacterized gene, LOC110373801 (designated HaVipR1), as a crucial determinant of Vip3Aa resistance in two field-derived resistant lines. Functional validation using CRISPR-Cas9 knockout in susceptible lines confirmed the genes role in conferring resistance. Despite extensive laboratory selection of Vip3Aa-resistant colonies in Lepidoptera, the biochemical mechanisms underlying resistance have remained elusive. Our research demonstrates that HaVipR1-mediated resistance operates independently of known resistance genes, including midgut-specific chitin synthase and the transcription factor SfMyb. The identification of HaVipR1 offers further insights into the Vip3Aa mechanism of action. This discovery is vital for devising strategies to counteract resistance and sustain the efficacy of Bt crops. Future research should focus on elucidating the biochemical pathways involving HaVipR1 and investigating its interactions with other resistance mechanisms. Our findings underscore the utility of analysing field-derived resistant lines in providing biologically relevant insights and stress the necessity for comprehensive management strategies to maintain agricultural productivity. Significance StatementThis is the first identification of a specific gene in Helicoverpa armigera which mediates resistance to the Bacillus thuringiensis (Bt) protein Vip3Aa. We identify that this gene is disrupted in two different ways in separate field-derived resistant lines, one being a large transposable element insertion in the first intron of the HaVipR1 gene, confirmed using long-read sequencing. Disruption of this gene using CRISPR-Cas9 knockout in a susceptible H. armigera line confers Vip3A resistance. The identification of a specific gene is important for molecular monitoring and management of H. armigera as well as other global pests of concern like Spodoptera frugiperda. These findings also offer insights for researchers aiming to understand how Vip3Aa functions, as the action pathway remains unclear.

genomics↗