Genetic markers associated with divergent selection against the parasite Marteilia cochillia in common cockle (Cerastoderma edule) using transcriptomics and population genomics data

The common cockle (Cerastoderma edule) plays an important role in marine ecosystems and represents a valuable socioeconomic resource for coastal communities. In 2012, the beds from Rı́a de Arousa (Galicia, NW Spain) were seriously decimated by protozoan Marteilia cochillia responsible marteiliosis. We aimed to identify single nucleotide polymorphisms (SNP) markers potentially associated with resilience marteiliosis be used marker-assisted selection programs restoring affected recovering their production. For this, we carried out population genomics approach using 2b-RADseq, where 38 naive samples (before first detection of M. 2012) two compared 39 collected 2018/2019 (after several years occurring area), either before (15 non-exposed samples) or during (24 exposed outbreak. Additionally, 767 differentially expressed genes (DEG) previous transcriptomic study addressed aforementioned 2018/19 outbreak, evaluated SNPs showing signals selection. Using 9,154 genotyped among them, 110 consistent outliers divergent identified. This set was able discriminate according status (naive vs affected; non-exposed), while another 123 identified linked DEGs level infection across temporal series. Finally, combining transcriptomics information, selected 60 most reliable resilience. These close within DEGs, many them related immune response (phagocytosis cell adhesion), defence, such as apoptosis, stress, cellular cycle, other functions. will eventually validated develop cost-effective genotyping tool application obtaining cockle-resilient strains