Dr. Valerie Pence, Cincinnati Zoo & Botanical Garden
Although there are published protocols for initiating shoot cultures for over 20 oak species, the cryopreservation of oak shoot tips has not been reported. We have applied the droplet vitrification protocol to four species of oaks, including the endangered Q. hinckleyi, in order to evaluate the feasibility of using shoot tip cryopreservation for oak ex situ conservation. Good survival through liquid nitrogen exposure was achieved for Q. virginiana, low survival for Q. hinckley and Q. suber, and no survival for Q. gambelii. Survival of Q. virginiana shoot tips was enhanced further by preculturing and recovering using an alternating temperature culture regime (25oC, 16 hr light/15oC, 8 hr dark). These results suggest that one procedure will not be ideal for all oak species, but that changes to the growth conditions can positively influence survival. Future studies will apply changes that were successful with Q. virginiana to oak species with lower levels of survival and other modifications will be made to work to improve survival for the other three species tested here, as well as for additional species in the CREW collection.