As the world’s population grows, so does the demand for proteins. Aquaculture, especially Pacific oyster farming, has immense potential to meet this need. However, a deadly disease called “summer mortality syndrome” caused by various Vibrio bacteria is devastating oyster farms and causing significant economic losses.
In this regard, scientists from the Ocean University of China and the Laoshan Laboratory conducted genomic selection of Pacific oysters (Crassostrea gigas) for genetic improvement of resistance to Vibriosis.
Limitations of Traditional Breeding
Breeding programs have focused on improving oyster growth, color, and nutrient composition. While some efforts have addressed disease resistance, they have not been particularly effective, especially against vibriosis.
Additionally, traditional selection methods based on phenotypic observations are slow and inefficient for complex traits such as disease resistance.
While traditional breeding programs have improved traits such as growth rate and shell color, they have not been effective against Vibrio resistance. This is where genomic selection comes in.
The Genomic Solution
The study introduces a turning point: genomic selection. This advanced technique uses the entire genetic composition of an oyster to predict its potential disease resistance, eliminating the need for time-consuming disease challenges.
Scientists conducted the first genomic selection study to breed Vibrio-resistant Pacific oysters. They identified key genetic markers associated with resistance and used them to predict the genetic value of candidate oysters. It is important to note that previous studies employed genomic selection of oysters for growth and identified genes for herpesvirus resistance.
How It Works:
- Identify the culprit: The study identifies Vibrio alginolyticus as the primary culprit of summer mortality on Chinese oyster farms.
- Building the prediction model: By analyzing the DNA of oysters with known resistance levels, scientists built four different prediction models.
- Finding the best model: Using a smart technique called cross-validation, researchers identified the most accurate model for predicting resistance.
- Breeding “Super Oysters”: Oysters with high predicted resistance (based on the best model) were bred, creating a new generation with potentially stronger defenses.
- Testing it out: This new generation was exposed to V. alginolyticus to confirm if the genomic prediction was accurate.
The Results
The study successfully demonstrated the effectiveness of genomic selection in breeding oysters resistant to vibriosis. This is the first time this technique has been used for this specific purpose, paving the way for a healthier and more sustainable oyster industry.
Offspring from parents selected based on their predicted resistance showed significantly higher survival rates when exposed to Vibrio compared to offspring from a control group. This demonstrates the effectiveness of genomic selection in breeding disease-resistant oysters.
Benefits for the Aquaculture Industry
The study’s findings have the following potential impacts for the aquaculture industry:
- Faster breeding: Compared to traditional methods, genomic selection can significantly speed up the development of disease-resistant oyster strains.
- Reduced losses: By growing resistant oysters, aquaculturists can minimize losses due to vibriosis outbreaks, increasing their economic stability.
- Sustainable aquaculture: This approach promotes a more sustainable and environmentally friendly aquaculture industry by reducing reliance on antibiotics and other treatments.
Conclusion
“We estimated the genomic heritability of Vibrio infection resistance in C. gigas using whole-genome SNP markers. The results showed that the heritability was at a low to moderate level, implying genetic improvement potential,” concluded the scientists.
This research paves the way for developing Vibrio-resistant oyster varieties faster and more efficiently than ever before. This not only benefits oyster breeders but also ensures a sustainable and healthy source of protein for future generations.
Furthermore, by further perfecting genomic selection techniques and applying them to other diseases, we can ensure a healthy and abundant supply of these delicious and nutritious bivalves for generations to come.
The study was funded by the National Key Research and Development Program of China, the Key Research and Development Program of Shandong Province, the National Natural Science Foundation of China, and the Agriculture Research System of China Project.
Contact
Shikai Liu
Key Laboratory of Mariculture (Ocean University of China)
Ministry of Education, and College of Fisheries, Ocean University of China, China.
Email: liushk@ouc.edu.cn
Reference (open access)
Yang, B., Zhi, C., Li, P., Xu, C., Li, Q., & Liu, S. (2024). Genomic selection accelerates genetic improvement of resistance to Vibriosis in the Pacific oyster, Crassostrea gigas. Aquaculture, 740679.
