Comparative Cryopreservation of Indian Wild Orange (Citrus Indica Tanaka) Embryonic Axes

BACKGROUND: Indian Wild Orange (Citrus indica Tanaka) is an endangered and endemic species from northeast India for which effective ex situ conservation strategies, including embryo cryopreservation, are urgently needed. MATERIALS AND METHODS: Desiccation tolerance and cryopreservation ability for embryonic axes of Citrus indica was determined using three techniques (air desiccation-freezing, PVS2 vitrification-freezing and encapsulation-dehydration-freezing). Success was assessed as survival and recovery in vitro. RESULTS: Successful cryopreservation of embryonic axes was achieved using all three methods, with the highest survival achieved when using air desiccationfreezing (90%) followed by encapsulation-dehydration (85%) and PVS2 vitrification cryopreservation (80%). Regeneration levels were lower than survival levels for all three proceedures. Post-cryo regeneration success was: encapsulation-dehydration (64%) > air desiccation-freezing (55%) > PVS2 vitrification (52%). CONCLUSION: Although there was relatively high post-cryopreservation recovery growth obtained using all the three techniques, the air desiccation-freezing technique is preferred, as it is a simple, practical and reproducible technique for the long-term cryobanking of this important wild species.