Enzymatic and nonenzymatic antioxidant defense in plants under cold or chilling stress

Abstract

Exposure to temperatures between 0 and 20°C that do not approach freezing is known as chilling, and it has long been recognized as a major stressor on plant growth, especially for agricultural species that originate in tropical or subtropical regions. While cooling stress can be detrimental, there are some processes in which it is advantageous. For instance, in many plant species, cooling is an essential environmental signal during vernalization, the process that triggers the change from vegetative development to blooming. Stratification, or the chilling of ingested seeds, is frequently necessary to break seed dormancy. Furthermore, cooling is essential for causing buds to become dormant in the fall (Heide & Prestrud, 2005). Through a process called cold-hardening or cold acclimation, chilling also helps some species acquire a resistance to freezing. All plants, however, view their first encounter with cooling or a drop in temperature as a stressor. Certain plants have the ability to adjust to this stress and acquire a tolerance to cold, but in other species, the exposure to stress causes certain developmental reactions.