Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: 11/2/2018
Publication Date: N/A
Technical Abstract: Dermo disease continues to limit aquaculture production of the eastern oyster, Crassostrea virginica. Disease resistance is a top priority for eastern oyster breeding programs, but simple methods to measure the trait directly are lacking, thereby reducing the efficiency of genetic improvement. Here we describe our efforts to better characterize Dermo resistance phenotypes and understand the genetic mechanisms underlying the response to this devastating disease. Oysters belonging to six distinct families within a selective breeding population were challenged with Perkinsus marinus, the parasite causing Dermo disease, according to optimized laboratory protocols. In addition to monitoring survival, five individuals · family-1 · treatment-1 were censored at 6hr, 7d, and 28d post exposure to assess changes in parasite load and gene expression over time. Gene expression profiles for three families exhibiting divergent resistance phenotypes were generated using RNAseq and differentially expressed genes at each time point were detected with DESeq2 and the Bayesian ApeGLM shrinkage estimator. As expected, the transcriptomic response to parasite exposure varied across families. The fewest differentially expressed genes (DEGs) were detected in the most susceptible family at early time points (34 and 24 at 36hr and 7d respectively); however, by 28d post-exposure, close to 897 genes were differentially expressed (most upregulated) between control and exposed individuals. We observed a more pronounced transcriptomic response in the Dermo-tolerant family immediately after exposure, but by 28d, expression levels for all but six genes were similar between the control and exposed treatments. Surprisingly few DEGs were detected in the Dermo-resistant family at each time point. The functional annotation of DEGs detected among the divergent phenotypes will further elucidate mechanisms of Dermo resistance and advance our ability to directly measure the trait within a selective breeding framework.