Estimating genetic parameters for resistance to Vibrio parahaemolyticus with molecular markers in Pacific white shrimp

Acute hepatopancreatic necrosis disease (AHPND), whose causative agent was Vibrio parahaemolyticus (VP_AHPND), has caused large economic loss in shrimp industry. To reduce the loss caused by AHPND, selective breeding aiming to improving the resistance of shrimp to VP_AHPND is a significant approach. However, to avoid common environmental effects and deal with situation of no ideal pedigree, developing genetic evaluation method based on molecular markers was necessary. The object of this study was to estimate the genetic parameters of the resistance to VP_AHPND in Pacific white shrimp, and to compare the estimation accuracies of shrimp breeding values on the resistance to VP_AHPND based on molecular relatedness (MR) and pedigree relatedness (PR) from pedigree reconstruction by cross validation. Twelve microsatellites were applied in 678 offspring (full data set), of which 351 offspring (reduced data set) were assigned to 50 female parents successfully. Heritability of the survival time (ST) and the survival status at the half-lethal time (SS₅₀) were 0.23 ± 0.10 and 0.12 ± 0.08 using PR in reduced data set. When MR was used, they were 0.15 ± 0.07 and 0.10 ± 0.06 estimated by the reduced data set, 0.20 ± 0.05 and 0.11 ± 0.04 estimated by the full data set. Cross-validation of both methods using the reduced data set showed an accuracy of estimated breeding values of 0.584 with PR and 0.608 with MR. Accuracy of estimated breeding values increased to 0.657 when applying MR to the full data set. Our results indicate that genetic improvement of shrimp is feasible and MR is an alternative to pedigree reconstruction in genetic evaluation for this trait.