Deacclimation and reacclimation of cold-hardy plants: Current understanding and emerging concepts

The abilities of cold-hardy plants to resist deacclimation during transient warm spells and to reacclimate when cold temperatures return are significant for winter survival. Yet compared to the volume of research on the biology of cold acclimation, relatively little is known about how plants maintain and/or reacquire cold hardiness in late winter and spring. This review summarizes the past 40 years of research into deacclimation and reacclimation in herbaceous and woody plants and suggests questions that should be addressed with multi-disciplinary approaches to more comprehensively understand the biology of winter-survival in plants. Deacclimation and reacclimation are highly dependent on exogenous and endogenous factors such as the ambient temperatures, water availability, photoperiod, energy budget and metabolism, growth and development, and the dormancy status of plants. Putative mechanisms of these hardiness transitions are discussed based on the published accounts of changes in carbohydrates (e.g., compatible solutes), membrane lipids, proteins (e.g., dehydrins), antioxidants, photosynthesis, and gene expression. In conclusion, the relationships between environmental determinants, gene expression and regulation, cellular and organismal structure and function, and the consequent cold hardiness transitions in plants are discussed and debated. # 2006 Elsevier Ireland Ltd. All rights reserved.