Potential for Genetic Improvement of Resistance to Perkinsus olseni in the Manila Clam, Ruditapes philippinarum, Using DNA Parentage Assignment and Mass Spawning

Type Article
Date 2020-10
Language English
Author(s) Smits Morgan1, Enez Florian2, Ferraresso Serena1, Dalla Rovere Giulia1, Vetois Emilie3, Auvray Jean-François3, Genestout Lucie4, Mahla Rachid4, Arcangeli Giuseppe5, Paillard Christine6, Haffray Pierrick2, Bargelloni Luca1
Affiliation(s) 1 : Department of Comparative Biomedicine and Food Science (BCA), University of Padova, Legnaro, Italy
2 : Syndicat des Sélectionneurs Avicoles et Aquacoles Français (SYSAAF), Laboratoire de Physiologie et Génomique des Poissons (LPGP), Campus de Beaulieu, Rennes, France
3 : Société Atlantique de Mariculture (SATMAR), Gatteville-Phare, France
4 : Labogena, Domaine de Vilvert, Jouy en Josas, France
5 : National Reference Centre for Fish, Crustacean and Mollusc Pathology, Italian Health Authority and Research Organization for Animal Health and Food Safety (IZSVe), Legnaro, Italy
6 : Laboratory of Marine Environmental Sciences (LEMAR), Institut Universitaire Européen de la Mer, Plouzané, France
Source Frontiers In Veterinary Science (2297-1769) (Frontiers Media SA), 2020-10 , Vol. 7 , P. 579840 (14p.)
DOI 10.3389/fvets.2020.579840
WOS© Times Cited 7
Keyword(s) Manila clam (Ruditapes philippinarum), Perkinsus olseni infection, disease resistance, genetic selection, genetic parameter estimation

The Manila clam Ruditapes philippinarum, a major cultured shellfish species, is threatened by infection with the microparasite Perkinsus olseni, whose prevalence increases with high water temperatures. Under the current trend of climate change, the already severe effects of this parasitic infection might rapidly increase the frequency of mass mortality events. Treating infectious diseases in bivalves is notoriously problematic, therefore selective breeding for resistance represents a key strategy for mitigating the negative impact of pathogens. A crucial step in initiating selective breeding is the estimation of genetic parameters for traits of interest, which relies on the ability to record parentage and accurate phenotypes in a large number of individuals. Here, to estimate the heritability of resistance against P. olseni, a field experiment mirroring conditions in industrial clam production was set up, a genomic tool was developed for parentage assignment, and parasite load was determined through quantitative PCR. A mixed-family cohort of potentially 1,479 clam families was produced in a hatchery by mass spawning of 53 dams and 57 sires. The progenies were seeded in a commercial clam production area in the Venice lagoon, Italy, where high prevalence of P. olseni had previously been reported. Growth and parasite load were monitored every month and, after 1 year, more than 1,000 individuals were collected for DNA samples and phenotype recording. A pooled sequencing approach was carried out using DNA samples from the hatchery broodstock and from a Venice lagoon clam population, providing candidate markers used to develop a 245-SNP panel. Parentage assignment for 246 F1 individuals showed sire and dam representation were high (75 and 85%, respectively), indicating a very limited risk of inbreeding. Moderate heritability (0.23 ± 0.11–0.35 ± 0.13) was estimated for growth traits (shell length, shell weight, total weight), while parasite load showed high heritability, estimated at 0.51 ± 0.20. No significant genetic correlations were found between growth-associated traits and parasite load. Overall, the preliminary results provided by this study show high potential for selecting clams resistant to parasite load. Breeding for resistance may help limit the negative effects of climate change on clam production, as the prevalence of the parasite is predicted to increase under a future scenario of higher temperatures. Finally, the limited genetic correlation between resistance and growth suggests that breeding programs could incorporate dual selection without negative interactions.

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Smits Morgan, Enez Florian, Ferraresso Serena, Dalla Rovere Giulia, Vetois Emilie, Auvray Jean-François, Genestout Lucie, Mahla Rachid, Arcangeli Giuseppe, Paillard Christine, Haffray Pierrick, Bargelloni Luca (2020). Potential for Genetic Improvement of Resistance to Perkinsus olseni in the Manila Clam, Ruditapes philippinarum, Using DNA Parentage Assignment and Mass Spawning. Frontiers In Veterinary Science, 7, 579840 (14p.). Publisher's official version : https://doi.org/10.3389/fvets.2020.579840 , Open Access version : https://archimer.ifremer.fr/doc/00658/77031/