Integrative Genomic Approaches to Improve Disease Resistance in Senegalese Sole: Insights from the BETTERFLAT Project

Introduction
The increasing global demand for seafood underscores the urgency of developing sustainable and resilient aquaculture systems. The Senegalese sole (Solea senegalensis), a species of high commercial value, plays a pivotal role in enhancing diversification and competitiveness within European aquaculture. However, its benthic nature heightens susceptibility to sediment-associated pathogens, making disease management a persistent production constraint. In alignment with the EU Aquaculture Strategy 2030, which prioritizes environmentally responsible disease mitigation, the BetterFLAT project aims to establish genomic resources to enable the selective breeding of disease-resistant Senegalese sole.

Materials and Methods
The BetterFLAT project employs an integrative multi-omics approach—combining functional genomics, transcriptomics, and molecular marker discovery—to identify genetic determinants associated with resistance to key bacterial pathogens. The consortium, comprising FLATLANTIC, IPMA, and S2AQUA, brings together expertise in aquaculture, pathology, and molecular biology to advance genetic improvement strategies for this species.

Results
An initial pre-test phase optimized pathogen challenge conditions by determining the median (LD₅₀) and 75% (LD₇₅) lethal doses for selected bacterial isolates. Experimental fish were subjected to a range of bacterial concentrations, and cumulative mortality was recorded to assess isolate virulence. Molecular characterization, including species confirmation and virulence gene profiling, validated the selection of the most pathogenic and genetically defined strain for subsequent infection trials.

Discussion and Conclusion
Through the integration of multi-omics datasets with pathogen-challenge experiments, the BetterFLAT project lays the groundwork for the development of disease-resilient Senegalese sole broodstock. These advances are expected to enhance juvenile robustness, reduce production losses, and promote more sustainable and economically viable aquaculture practices.

Acknowledgments
The operation BetterFLAT was developed with funding from Programmes COMPETE2030, Algarve2030, Portugal2030, and the European Union; the Interface Mission cofinanced by PRR - Plano de Recuperação e Resiliência by the European Union (operation code 01/C05-i02/2022.P148); and SAUDE&AQUA II (MAR-021.1.3-FEAMPA-00018).