Ji Woong Lee1, Ji Hye Park2, and Gwang Hoon Kim3
1Fisheries Seed and Breeding Research Institute, National Institute of Fisheries Science, Haenam 59002, Republic of Korea
2Department of Genetic Resources Research, National Marine Biodiversity Institute of Korea, Seocheon 33662, Republic of Korea
3Department of Biological Sciences, Kongju National University, Gongju 32588, Republic of Korea
Pyropia yezoensis is tolerant to extreme desiccation and low temperature stressors and thrives in a highly dynamic intertidal environment. These characteristics have been exploited by sea farmers to create cryopreservation method that incorporate drying and freeze processing. Cryopreserved cultivation nets are used in around 20% of Pyropia aquaculture today, but studies on the connection between cryopreservation-induced abiotic stress and disease-induced biotic stress is lacking. In this study, we investigated response of P. yezoensis to combined drying and freezing stresses and their impact on the incidence of the oomycete diseases (Olpidiopsis and Pythium). When P. yezoensis thalli were immersed in seawater and frozen (-20 °C), only a few cells (<5%) survived after thawing, whereas more than 90% of cells survived when the thalli were treated to drying prior to freezing as in cryopreservation method. The infection rate as well as the progress of oomycete diseases were reduced after cryopreservation treatment to less than half that of the control. The pretreatment with cryopreservation induced the continuous regulation of HSP genes that response to infection of oomycete diseases. These results suggest that the proper drying and freezing methods can induce cross-tolerance to biotic stress in P. yezoensis, and cryopreservation as aquaculture technology can be useful as a treating measure for oomycete diseases.