Sydney rock oysters (SRO) are indigenous to Australian waters and contribute to the economy greatly. In recent years, however, the SRO industry has witnessed a continuous decline in production, which can be attributed mainly to Queensland unknown (QX) and winter mortality (WM) diseases, in conjunction with environmental factors and anthropogenic pollution. The diseases together are responsible for > 80% of the mortality of oysters in the estuaries in NSW.

In 1990s DPI-NSW initiated a breeding program to tackle the loss by selection of broodstock that survived the disease outbreaks, without any knowledge of the molecular basis of resistance. This project is an attempt to connect the missing links between selection and the biological processes associated with it.

In this baseline study we aim at identifying the proteins differentially regulated in QX and winter mortality selected Sydney rock oysters when compared against non-selected oysters, employing both two dimensional protein gel electrophoresis and shotgun proteomics. We have identified proteins which are differentially regulated in winter mortality and QX. These proteins were found to be associated with different biological processes including stress response, cytoskeleton, cell communication, energy metabolism and protein synthesis. Identification of their biological significance has led to a better understanding of the underlying molecular processes associated with the disease selection. This ongoing study requires further substantiation, but results are already being used to help in breeding better oysters.