The effect of antifreeze protein on the cryopreservation of chrysanthemums

To our knowledge, this is the first study to show the application of antifreeze protein (AFP) in the cryopreservation of ornamental plants. We studied the effect of AFP on the cryopreservation of Chrysanthemum grandiflorum (Ramat.) Kitam ‘Borami’, ‘Secret Pink’, and ‘Yellow Cap’. For all cultivars, survival and regrowth rates were higher in shoot tips vitrified with plant vitrification solution 3 (PVS3) containing various concentrations of AFP than in those vitrified with PVS3 alone. The optimal AFP concentration was genotype-dependent. Scanning electron microscopy revealed that shoot tips vitrified with PVS3 containing AFP had less freezing injuries than those treated with PVS3 alone. Analysis of the enthalpy in each sample by differential scanning calorimetry supported the finding that AFP is a potent cryoprotectant that can reduce the freezing point of water in plant tissues. We expect that our results will facilitate the successful application of AFPs in the cryopreservation of rare and commercially important plant germplasm.