What happens in plant molecular responses to cold stress?

Low temperature is one of the major abiotic stresses limiting the productivity and the geographical distribution of many important crops. Many plants increase in freezing tolerance in response to low temperatures. This phenomenon needs a vast reprogramming of gene expression which results in the adjusted metabolic-structural alterations. However, the efficient adjustments are dependent on proper cold signal transduction. The first stage is cold stress signal perception which is carried out by different pathways. Transcriptional cascades are next players which operate through ABA-dependent and ABA-independent pathways to induce cold-regulated (COR) gene expression and the result is increasing in the levels of hundreds of metabolites, which some of them are known to have protective effects against the damaging effects of cold stress and some like soluble sugars, reactive oxygen species and photosynthetic metabolites are thought to act as signaling molecules and regulate special COR genes. The different aspects of these events are discussed in detail below.