Role of salicylic acid in acclimation to low temperature

Low temperature is one of the most important limiting factors for plant growth throughout the world. Exposure to low temperature may cause various phenotypic and physiological symptoms, and may result in oxidative stress, leading to loss of membrane integrity and to the impairment of photosynthesis and general metabolic processes. Salicylic acid (SA),phenolic compound produced by a wide range of plant species, a may participate in many physiological and metabolic reactions in plants. It has been shown that exogenous SA may provide protection against low temperature injury in various plant species, while various stress factors may also modify the synthesis and metabolism of SA. In the present review, recent results on the effects of SA and related compounds in processes leading to acclimation to low temperatures will be discussed

Interaction of Temperature and Light in the Development of Freezing Tolerance in Plants

Abstract Freezing tolerance is the result of a wide range of physical and biochemical processes, such as the induction of antifreeze proteins, changes in membrane composition, the accumulation of osmoprotectants, and changes in the redox status, which allow plants to function at low temperatures. Even in frost-tolerant species, a certain period of growth at low but nonfreezing temperatures, known as frost or cold hardening, is required for the development of a high level of frost hardiness. It has long been known that frost hardening at low temperature under low light intensity is much less effective than under normal light conditions; it has also been shown that elevated light intensity at normal temperatures may partly replace the cold-hardening period. Earlier results indicated that cold acclimation reflects a response to a chloroplastic redox signal while the effects of excitation pressure extend beyond photosynthetic acclimation, influencing plant morphology and the expression of certain nuclear genes involved in cold acclimation. Recent results have shown that not only are parameters closely linked to the photosynthetic electron transport processes affected by light during hardening at low temperature, but light may also have an influence on the expression level of several other cold-related genes; several cold-acclimation processes can function efficiently only in the presence of light. The present review provides an overview of mechanisms that may explain how light improves the freezing tolerance of plants during the cold-hardening period