Viability of embryonic axes of Araucaria angustifolia after freezing using two cryopreservation methods

Araucaria angustifolia (Bertol.) O. Kuntze is one of the most important native species in Southern Brazil. However, its naturally recalcitrant seeds represent obstacles for long-term conservation and thus cryopreservation is a viable alternative for germplasm storing. Embryonic axes (EA) excised from araucaria seeds were encapsulated, dehydrated, and submitted to two cryopreservation methods: flash-cooling by freezing in liquid nitrogen (LN) for 2 h and pre-cooling at – 40 °C, followed by freezing in LN for 2 h. Subsequently, the EA were quickly thawed and assessed for DNA integrity, tetrazolium test, in vitro germination and oxidation occurrence. The DNA of both not cryopreserved and cryopreserved EA maintained their integrity. The tetrazolium test results indicated that the majority of flash-cooled EA were viable. After 15 days of in vitro culture, the EA did not germinate and presented signs of oxidation. Dehydration method by direct plunge in LN is promising for cryopreservation of araucaria EA, as demonstrated through the results of tetrazolium test and the maintenance of total DNA integrity.