Periodic Reporting for period 1 - HYBRIPEST (Unravelling the molecular-genetic underpinnings of hybrid defects in agricultural pests)
Reporting period: 2023-05-01 to 2025-10-31
In animals, healthy offspring are not guaranteed from every mating. Offspring from certain crosses may suffer from severe defects, including sterility and mortality. These hybrid defects can evolve rapidly and occur within species and between species that hybridize. Hybrid dysfunction is an isolating barrier that can drive speciation and maintain species barriers. The underpinning genetic processes have captivated generations of evolutionary biologists. Pest control programs that introduce hybrid defects in pest populations are a promising management strategy for agricultural pests and disease vectors. Unravelling the underpinning molecular-genetic mechanisms is essential to fully understand the evolution of hybrid dysfunction, its potential contribution to speciation, and how these incompatibilities can be harnessed for effective pest control. In HYBRIPEST, we focus on Wolbachia-mediated and nuclear-mediated incompatibility.
We established, genotyped, and phenotyped reference panels of two Tetranychus mite species, spanning their global genetic diversity. We coupled the penetrance of Wolbachia-mediated cytoplasmic incompatibility to cif gene repertoires, cif transcription, and infection density. We introduced multiple Wolbachia variants into novel host backgrounds and quantified the impact of transinfection on CI strength and infection density. We are currently dissecting the host genic factors that shape CI strength. In parallel, we quantified the expression of intraspecific and interspecific hybrid sterility in these reference panels. For these experiments, we developed a novel high-throughput genotyping tool to guarantee that these mite lines are not infected with reproductive symbionts. Leveraging our genomic and phenotypic data of European populations, we discovered likely cases of strong nuclear-mediated reproductive isolation within and between hybridizing Tetranychus species. We show that hybrid sterility can be easily recovered by generating specific recombinants. We are now dissecting causal genic factors.
HYBRIPEST will generate a deeper understanding of how endosymbiosis evolves and how symbionts may be harnessed for pest control. In parallel, HYBRIPEST delivers key mechanistic insight into early speciation, an enigmatic phase that continues to fascinate evolutionary biologists.