|CORBETT, RYAN - University Of Rhode Island|
|BEN-HORIN, TAL - University Of Rhode Island|
|SMALL, JESSICA - Virginia Institute Of Marine Science|
|ALLEN, STANDISH - Virginia Institute Of Marine Science|
Submitted to: Aquaculture Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/13/2019
Publication Date: 7/8/2019
Citation: Proestou, D.A., Corbett, R., Ben-Horin, T., Small, J., Allen, S. 2019. Defining demo resistance phenotypes in an eastern oyster breeding population. Aquaculture Research. 50:2142-2154.
Interpretive Summary: The objective of this study was to develop methods for characterizing eastern oyster phenotypes associated with resistance to Dermo disease and determine whether they vary within an eastern oyster breeding population. Twenty oyster families developed at the Aquaculture Genetics and Breeding Technology Center were injected with the disease-causing parasite and monitored for survival over a 42-day period. The rate at which the parasite was eliminated from oyster tissues was also quantified. Both measures provided estimates of disease resistance in the absence of environmental noise and varied among the eastern oyster families tested. Accurate estimates of disease resistance are necessary for enhanced genetic improvement of the trait. These findings have important implications for oyster breeding strategies and industry practices. Tools that enable the selection of oyster stocks that are more resistant to Dermo disease will increase eastern oyster production.
Technical Abstract: Perkinsus marinus, the causative agent of Dermo disease, is responsible for mass mortalities and negatively impacts aquaculture production of the eastern oyster, Crassostrea virginica. Selective breeding is a viable option for Dermo disease management; however, fluctuations in natural selection pressure and environmental noise hinder accumulation of genetic gains acquired through field performance trials. The purpose of this study was to adapt and apply laboratory disease challenge methods to eastern oysters, better characterize resistance-specific traits, and assess the potential for genetic variation in Dermo resistance among distinct families within a breeding population. Two challenge experiments were conducted, one in 2014 and the other in 2015. Significant treatment (control vs. challenged) and family effects on survival (measured as percent survival and days to death) were detected in the 2014 challenge, while overall high survival precluded the detection of a significant family effect in the 2015 challenge. An alternate measure of resistance, parasite elimination rate, was also measured in the 2015 challenge, and this varied significantly among families. Thus, both survival and the change in parasite concentration in oyster tissues over time represent Dermo resistance phenotypes that can be measured accurately with the adapted laboratory disease challenge protocol described here. The obvious next step is to incorporate the challenge protocol in eastern oyster breeding programs to assess whether well-defined, accuratelymeasured, Dermo-resistant phenotypes result in enhanced genetic improvement for this commercially important trait.