Mapping for males: Sustainable sex control in nile tilapia

D'Cotta Helena, Triay Cécile, Sissao Rokyatou, Bezault Etienne, Conte Matthieu, Courcelle Maxime, Caminade Pierre, Toguyeni Aboubacar, Kocher Thomas D., Baroiller Jean-François. 2022. Mapping for males: Sustainable sex control in nile tilapia. Aquaculture Journal, 2 (2), p. 95 Genomics in Aquaculture (GIA). 6, Grenade, Espagne, 4 Mai 2022/6 Mai 2022.

Résumé : Sexual dimorphism of aquaculture traits is common for farmed fish. The Nile tilapia is the second most important farmed species with a production 6 million tons in 2020. Intensive farming relies on the production of all-males due to males' higher growth rate, and as a way to avoid uncontrolled reproductions. Currently the large majority of the all-male productions are obtained through androgen treatments. We aim to use more sustainable procedures to produce all-males such as the use of YY males. Until now, the use of YY males has not been reliable. This is because sex determination in Nile tilapia is complex and controlled by several factors. Although sex determinism follows an XX/XY system, the linkage group (LG) carrying the major sex determinant gene has been assigned to either LG1 or LG23, depending on the domesticated strain. Minor parental factors can also be implicated and in addition, high temperatures can override the genetic determinism. It is not clear to what extent these differences in sex determination are due to natural diversity in the mechanisms of sex determination or due to processes of domestication. It is therefore necessary to better understand the genetic basis of sex determinism in order to use this approach to generate all-males. For this, we decided to work on wild populations in Africa that have not suffered domestic manipulations. We underwent a study of sex determination in several wild populations from West (Lake Volta, Lake Kou) and East Africa (Lake Koka and Lake Hora). We used complementary genomic approaches of ddRAD, whole genome sequencing and long Nanopore reads. We were able to determine that the amh region present on LG23 is the major sex-determining region in most of these populations. Nevertheless, our results also show that there is high polymorphism in this SD region. Furthermore, there are populations that lack the male-specific amh duplication on LG23. Hence, there are no universal Y markers for Nile tilapia. It is necessary to work at the population level to identify and validate sex markers, in order to allow the local production of YY males.

Mots-clés Agrovoc : Oreochromis niloticus, sexage, chromosome sexuel, génomique, génétique animale

Mots-clés libres : Oreochromis niloticus, Sex control, Sex chromosomes, Genomics

Classification Agris : L10 - Génétique et amélioration des animaux
L01 - Élevage - Considérations générales

Champ stratégique Cirad : CTS 2 (2019-) - Transitions agroécologiques

Agences de financement européennes : European Commission

Programme de financement européen : H2020

Projets sur financement : (EU) European Aquaculture Training for improving Seafood Husbandry

Auteurs et affiliations

• D'Cotta Helena, CIRAD-PERSYST-UMR ISEM (FRA) ORCID: 0000-0003-2739-3476
• Triay Cécile, CIRAD-PERSYST-UMR ISEM (FRA)
• Sissao Rokyatou, Université Nazi Boni (BFA)
• Bezault Etienne, Université des Antilles (GLP)
• Conte Matthieu
• Courcelle Maxime, CIRAD-BIOS-UMR ASTRE (FRA)
• Caminade Pierre
• Toguyeni Aboubacar, Université Nazi Boni (BFA)
• Kocher Thomas D., University of Maryland (USA)
• Baroiller Jean-François, CIRAD-PERSYST-UMR ISEM (FRA) ORCID: 0000-0002-0992-1725

Source : Cirad-Agritrop (https://agritrop.cirad.fr/602557/)

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