Jin-Mei Zhang, Bin Huang1, Xiao-Ling Chen
Recent advances in cryopreservation techniques have greatly enhanced our knowledge of the cryopreservation of clonal crops and recalcitrant-seeded species. Various species of Petunia (Petunia × hybrida Vilm.) are used both as popular horticultural plants and as model systems for plant molecular biology research. A previous study on conventional cryopreservation of petunia suspension cultures in liquid nitrogen may exhibit somaclonal variations in recovered cells, thereby necessitating the development of a cryopreservation technique using shoot tips as explant sources. A droplet-vitrification cryopreservation protocol of petunia shoot tips has been efficiently developed, and nowadays four petunia accessions have been successfully cryopreserved in National GeneBank of China using this method. Furthermore, histological observations of petunia meristem cells were performed at critical steps via transmission electron microscopy during droplet-vitrification. Cytological responses were observed after the preculture, loading and PVS2 steps. Further research is required to understand the cytological, biochemical, and molecular responses of cells during cryopreservation.