Proteomic analysis of crop plants under low temperature: a review of cold responsive proteins

Cold stress is one of the major environmental limiting factors affecting growth, development, and geographical distribution of many plant species especially in temperate regions where plants are seasonally exposed to low or freezing temperatures. During evolution, plants have evolved physiological, morphological, and molecular mechanisms to tolerate low temperatures. Understanding the molecular basis of plant cold stress tolerance is of great importance since it provides valuable information required for improving cold stress tolerance of existing crop cultivars with high yield and limited tolerance to low temperatures. At molecular level, the response of plants to low temperatures include changes in expression, abundance, post translational modifications, and subcellular localization of proteins which allow plants to adapt to low temperatures and to withstand freezing. Comparative proteomic analyses have revealed a list of proteins that are newly synthesized, induced or repressed in response to low temperature in different crop species. These include proteins whose functions are directly involved in cold and freezing tolerance including dehydrins, late embryogenesis abundant (LEA) proteins, cold regulated (COR) proteins, anti-freezing proteins, and pathogenesis related (PR) proteins. Cold stress is always associated with changes in cellular homeostasis which leads to an increased generation of reactive oxygen species (ROS) and therefore, elicits profound changes in abundance and activities of ROS scavenging enzymes. In addition, during cold stress, the abundance of proteins associated with carbohydrate metabolism, photosynthesis, protein synthesis and processing including those involved in folding and repairs of damaged proteins changes significantly to alleviate the damaging effects of low temperature. In this chapter, proteomics tools and techniques are introduced and the challenges faced with plant materials are discussed. Subsequently, the function of cold responsive proteins is reviewed in the context of cold stress tolerance in different crop species.