Ice Nucleation and Freezing Consequences in Perennial Plants

The precise location where ice forms in plants affects the physical constraint it exerts on the different biological compartments (cells, tissues, organs). It is therefore critical to understand where and how ice nucleates to predict the extent of low temperature damage. On one hand, extracellular ice formation can protect living plant cells by lowering their intracellular freezing point through water efflux and an increase in osmolyte concentration. On the other hand, extended freezing-induced dehydration may cause damage and rupture of the plasma membrane. The location and pattern of ice formation in plants are marked by high spatio-temporal variability in relation to the type of plant tissue, its developmental stage, and the nature of the initial ice nucleus. This review focuses on the mechanisms and dynamics of intrinsic ice nucleation and subsequent propagation in perennial plants. We describe the factors that influence ice nucleation, such as the nature of nucleating agents and other biophysical conditions. We also highlight the shortcomings of studies on plant freezing, especially regarding laboratory studies, and emphasize the need to investigate ice nucleation in plants using interdisciplinary approaches. We finally provide a practical workflow to guide new experimenters in this research field.