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Dehydrins (DHNs) as the member of the late embryogenesis abundant protein family, play critical roles in seed dehydration protection and plant adaptation to multiple abiotic stresses. As an important method of germplasm preservation, cryopreservation is also an ideal research system to study compound stress. Oxidative stress, as the critical stress in cryopreservation, directly affects cell viability. Our previous in vitro tests indicated that ApY2SK2 DHN can effectively protect enzyme activity and almost double the survival rate of Arabidopsis thaliana seedlings after cryopreservation, but the in vivo protective effect of ApY2SK2 on cryopreservation have not yet been elucidated. In this study, ApY2SK2 type DHN was genetically transformed into embryogenic callus (EC) of Agapanthus praecox by overexpression (OE) and RNA interference (RNAi) techniques to evaluate the in vivo oxidative stress protective effect of DHNs during cryopreservation. The results showed that the cell viability had a completely opposite trend between OE and RNAi cell lines, and the cell relative death ratio of ApY2SK2-OE EC was significantly decreased 18.5% and ApY2SK2-RNAi cells was significantly increased 23.5% after cryopreservation. Overexpression ApY2SK2 increased non-enzymatic antioxidant (AsA and GSH) contents, antioxidant enzyme (POD and SOD) activities and up-regulated CAT, POD and GPX expression, while ApY2SK2-RNAi cells decreased CAT, FeSOD, POD and GPX expression during cryopreservation. These findings suggested that ApY2SK2 can affect ROS metabolism, alleviate H2O2 and OH·excessive generation, activate the antioxidant system, improve cellular REDOX balance and reduce membrane lipid peroxidation damage of plant cells during cryopreservation. DHNs can effectively improve cell stress tolerance and have great potential for in vivo or in vitro applications in plant cryopreservation.
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