S02 - Session O3 - Conservation of dragon fruit genetic resources using seeds as well as clonal material

Authors: Hannes Wilms *, Natalia Fanega Sleziak, Jacob Merckx, Nils De Laet, Bart Panis

Dragon fruit or Pitaya is the fruit of a group of cactus species of the genus Hylocereus or Selenecereus , grown for its delicious taste and ornamental value. While the species originated from the Americas, it is now cultured in many places in the Tropics. Breeders and farmers continuously improve the species, resulting in different tastes and higher resistance to pests, diseases, and drought. Since they are CAM plants, they can be cultivated in arid areas and can be used against desertification. Therefore, breeders and farmers need access to the broadest possible diversity of wild and cultivated material. In commercial plantations, pitaya plants are propagated vegetatively, meaning that seed propagation and conservation (as is the case for many fruit crops) are not effective methods since the unique gene combination of the clone is lost. Alternative ex-situ conservation measures are needed to field collections subject to destructive environmental exposure, such as pests, diseases, and adverse weather conditions. Therefore in vitro cultivation and cryopreservation methodologies need to be developed for this crop. Seed conservation, however, is still very valuable for wild or hybrid varieties. Our study focuses on both clonal and seed conservation. To preserve clonal material, we initiated vines of the cactus in vitro and grew them for several months without observing any morphological changes. Also, preliminary results on the cryopreservation of meristems excised from theses in vitro cultures using droplet vitrification proved promising. To preserve pitaya seeds, we determined their humidity. We dried them to different moisture contents, whereafter they are stored in dark airtight packages at room temperature(~20░C), in the fridge (7░C) or freezer (-20░C). The first results after six-month storage indicate that the seeds are likely orthodox, with no significant differences in germination with our control group at day 0.