Genetic aspects of disease resistance in oysters

Like other phenotypic traits, resistance to disease is generally subject to underlying genotypic variability. This may come about indirectly, as a result of variation in overall physiology or in life history characteristics, or may be more directly attributable to variation in cellular or biochemical mechanisms. We summarize here our current understanding of genetic influences on physiological and life history variation in Crassostrea and review the evidence available to date on intra- and interspecific genetic variation in disease resistance, with emphasis on Perkinsus marinus and MSX. We also describe our current view of population structure in Crassostrea virginica, and how it may affect the evolution of disease resistance. Finally, we explore approaches to the development of disease-resistant oysters that capitalize on the genetic variability inherent in C. virginica and within the genus Crassostrea.