We developed a novel strain of red sea bream Pagrus major that showed resistance to red sea bream iridoviral disease (RSIVD) using marker-assisted selection combined with DNA-based family selection and evaluated survival of its G 2 in a farm environment. The G 1 population was derived from a single RSIVD-resistant male (G 0 ). The G 1 progeny of the resistant male were identified by DNA parentage analysis using microsatellites. Marker-assisted selection using a quantitative trait locus linked to the RSIVD-resistant trait (Pma4_014) was conducted, and individuals inheriting the resistant allele of Pma4_014 (+) were selected. Two G 2 populations were produced in 2016 and 2017, and reared for approximately three months, during the summer, at an aquaculture facility. A normal production cohort was also reared at the same farm in 2016 and survival compared. Survival rates of the G 2 populations produced in 2016 and 2017 were 78.8% and 83.5%, respectively. The survival rate of the 2016 normal production cohort was 63.8%. The segregation pattern of the resistant allele showed 1 (+/+): 2 (+/−): 1 (−/−) in G 2 , and genotype frequency of Pma4_014 was calculated using approximately 200 individuals collected from 2016 and 2017 G 2 populations before and after the field trial. Numbers of each genotype were estimated based on the number of introduced and surviving fish. Individuals with the resistant allele, (+/+) and (+/−), showed over 80% of the estimated survival rates, but individuals without the resistant allele (−/−) showed lower survival (50%) in both years. This result strongly suggests that the resistant allele dominantly affects RSIVD resistance, and the newly developed G 2 population is useful for further propagation of RSIVD-resistant red sea bream fingerlings.
All Science Journal Classification (ASJC) codes
- Aquatic Science