Exogenous ethylene increases the viability of cryopreserved Dendrobium protocorm-like bodies by regulating the hydrogen peroxide and its mediated oxidative stress

Cryopreservation, an effective method for long-term preservation of germplasm resources, but after liquid nitrogen (LN) preservation, the survival rate of some species/cultivars has decreased or even zero. Exogenous ethylene additives are added to in the preculture stage of vitrification-cryopreservation using the protocorm-like bodies (PLBs) of Dendrobium nobile Lindl. ‘Hamana Lake Dream’ as materials, to study the effects of ethylene on cell survival rate, the level of hydrogen peroxide (H 2 O 2 ) and oxidative stress indicators of the cryopreserved PLBs. The results showed that the addition of exogenous ethylene (ethephon, ETH) can significantly improve the endogenous 1-aminocyclopropane-1-carboxylic acid (ACC) content and cell survival rate of Dendrobium PLBs after cryopreservation by vitrification, reduce the content of endogenous H 2 O 2 , and increase the activity of catalase (CAT) and ascorbic acid peroxidase (APX). While, the addition of exogenous ethylene inhibitor (cobalt nitrate, Co), the endogenous ACC content and the cell survival rate of PLBs after cryopreservation by vitrification were significantly reduced and the levels of endogenous H 2 O 2 was significantly increased, and the activity of CAT, APX and ascorbic acid (AsA) content were significantly reduced. These observations suggest that exogenous ethylene can improve the survival rate of Dendrobium PLBs after cryopreservation by regulating the H 2 O 2 and its mediated oxidative stress. In addition, the way ethylene regula tes endogenous H 2 O 2 levels may be closely related to the AsA-glutathione (GSH) antioxidant circulation system. Key message Adding appropriate concentration exogenous ethylene can improve endogenous ACC content and the survival rate of Dendrobium PLBs after cryopreservation by regulating the H 2 O 2 and its mediated oxidative stress.