Plant antifreeze proteins

Plants are increasingly subjected to episodes of spring frost injury due to erratic weather patterns fostered by climate change. While many plant species undergo a seasonal cycle of cold acclimation and deacclimation, warm, late-winter temperatures induce plants to lose their frost tolerance and thus experience lethal injury when more seasonable freezing temperatures return. The production of plant antifreeze compounds (AFPs) is among the mechanisms that plants use to cold acclimate and either avoid freezing or limit the damage caused by the formation of large ice crystals in their tissues. The current review describes the process of cold acclimation in plants and the potential role antifreeze proteins may have in promoting cold hardiness. The discovery of plant antifreeze proteins, their production in different higher plant and algal species, the three-dimensional structure of AFPs, the potential role of AFPs in ice nucleation and propagation, and attempts to improve plant freezing tolerance by the production of insect AFPs in transgenic plants is discussed. The potential application of plant AFPs in the food industry is also presented. Lastly, the ability of plants to exhibit deep supercooling as an alternative method of freeze avoidance and the role of sugars with AFPs in freezing point depression and reducing the adhesive stress resulting from the presence of ice is discussed.