Cold and frost are stress factors of widespread occurrence for plants. They damage woody plants due to chilling temperatures in the tropics, by freezing sensitive plants in regions with episodic frosts and temperatures down to -10°C, and by freezing of even tolerant plants in regions with cold winters below -10 and -40°C. The wide range of frost resistances in plants from different climatic zones indicates that the ability to become hardened to freezing has evolved in a stepwise process. There are opinions how an evolutionary acquisition of freezing tolerance could have taken place in the following way: First there is a differentiation of better adapted ecotypes and in the long term a series of functional plant groups develop along climatic gradients. Frequent climatic stress and climatic changes stimulate the selection of new genotypes resistant to climatic extremes. Furthermore, plants exposed to multiple stress factors in their habitat acquire a general cross-tolerance to climatic constraints.
The objective of this review is the understanding of low temperature resistance in woody plants, e.g. stabilization of biomembranes by lipid composition, deep supercooling, and ability to become freezing tolerant during winter dormancy. An over a hundred year long history of investigating frost stress and survival of different plant species has brought about an important understanding of basic processes. Recently antifreeze proteins which slow the freezing processes, and proteins, which protect the protoplasm against low temperature, frost and dehydration have been discovered. Findings that help to explain the mechanisms for coping with low temperature will be applicable to agriculture, horticulture, forestry and bioclimatology.
2005 The Society of Agricultural Meteorology of Japan