Oyster Genomics Breeding Program

March 21, 2018

PEARL is developing an oyster genomics breeding program, headed by Dr. Ming Liu, which will use cutting-edge research to address one of the critical issues of the Chesapeake Bay. The Bay is one of the largest oyster production areas in the U.S., and the local oyster aquaculture industry has experienced rapid growth over the past decade - helping to fill the production void caused by the diminished wild oyster fishery. However, the oyster aquaculture is grappling with two challenges that threaten its continued growth: 1) mortality caused by diseases, especially among on-bottom cultured oysters, and 2) slow growth for diploid oysters due to low salinity. These challenges are driving the demand for oyster stock lines that exhibit high survivorship and excellent performance in the low-salinity waters of the Chesapeake Bay.

In the past, selective breeding has been shown to improve oyster performance, but there are limited successful lines currently available. Traditional selective breeding based on phenotype requires continuous selection across many generations, necessitating long-term commitments of funding and space allocations to hold and maintain broodstock over many years. When the heritability of desirable trait is small, the selection efficiency is especially low. Continuous multi-generation selection may also result in low genetic diversity within the selected lines, leading to inbreeding depression such as slow growth and low larval survival. This creates a high risk for a population crash if a new disease is introduced or a dramatic environmental change occurs. Moreover, the limited number of available oyster lines results in frequent seed transportations, but transplanted oysters may not be as well adapted for their new environments, resulting in lower performance.

Focusing on these issues and limitations, PEARL will use a genomic approach including marker-assisted selection (MAS) and genomic selection (GS) to assist in the selective breeding of oysters, with the goal of developing a more robust production of oysters with favorable traits for the Chesapeake Bay that can be used by the aquaculture industry. The hypothesis of this method is that favorable traits are determined genetically. By identifying the determinative loci or the alleles tight-linked to the loci, we are able to target the broodstock which could directly produce offspring with desirable traits, rather than through multi-generation inbred crossing. This approach allows us to improve oyster performance from local wild oyster broodstock without requiring long-term stock holding for a hatchery. The selected lines hence may have higher genetic diversity and adaptability.

Dr. Liu's post-doctoral research focused on genomic study in oyster disease at Haskin Shellfish Research Laboratory, Rutgers University. He identified several alleles highly associated with disease-resistance, and used those to produce experimental disease-resistant lines in New Jersey. At PEARL, Dr. Liu is continuing research on improving the disease-resistance of Maryland oysters, and is also focusing on the identification of genes and markers associated with hypoosmotic-adapted and growth. The oyster genomics breeding program's objective is to produce disease-resistant, rapidly growing oyster lines as a resource for the local oyster aquaculture industry. PEARL's program will focus on continuous genetic improvement to produce oyster lines with superior performance and traits desirable to the industry. We will also offer our validated molecular breeding technology and services to hatcheries.

We look forward to collaborations with both industry and research partners to support the Bay's oyster aquaculture. Please contact Dr. Ming Liu with questions or to discuss collaboration opportunities at ming.liu@morgan.edu, 443-885-5922.