In 2007, Dr. Hui Gong and her research team initiated a shrimp (Penaeus vannamei) breeding program at the University of Guam Hatchery. It is crucial to maintain clear pedigree lines and minimize inbreeding in the program for sustainability purposes. This could be done by physically tagging, which is a monumental task, as the researchers would need to physically tag each individual animal. There is also the strong possibility of losing the tag during the molting process of the shrimp or of misreading the tag, which would pose great difficulties and confusion for processing and interpreting data.
Therefore, Dr. Gong’s team aimed to develop a panel of useful internal markers, in order to maintain the shrimp breeding program, and ultimately improve the genetic diversity of shrimp stocks for the aquaculture industry on Guam and the region.
Gong’s team used a panel of 16 polymorphic markers selected from 128 microsatellite loci (positions of genes in chromosones) that were screened using pooled DNA samples from Guam Aquaculture Development Training Center (GADTC) stock. This work has been carried out in multiple generations of the program. The parents of 36 shrimp families and 30 progeny per family were sampled and genotyped. Their work allows them to identify pedigrees and facilitates marker-assisted selection, which may link genetic markers to desirable phenotypic traits.
To determine the minimum number of microsatellite markers required for accurate pedigrees, parentage assignment using various numbers of markers was compared with the known pedigree. Two computer programs, CERVUS and COLONY, were used to analyze the data and both programs concurred that 12 or more loci yielded 100% accuracy in assigning the correct parents at the genotyping error level of 1%.
The panel of these informative microsatellite markers developed in this study will be optimized and effectively employed in shrimp breeding programs at the hatchery for monitoring genetic diversity and managing the program.
Funded by USDA T-STAR & USDA HATCH