Arabidopsis COLD SHOCK DOMAIN PROTEIN 2 is a negative regulator of cold acclimation.

Bacterial cold shock proteins ( CSPs) act as RNA chaperones that destabilize m RNA secondary structures at low temperatures. Bacterial CSPs are composed solely of a nucleic acid-binding domain termed the cold shock domain ( CSD). Plant CSD proteins contain an auxiliary domain in addition to the CSD but also show RNA chaperone activity. However, their biological functions are poorly understood., We examined Arabidopsis COLD SHOCK DOMAIN PROTEIN 2 ( At CSP2) using overexpressing and mutant lines., A double mutant, with reduced At CSP2 and no At CSP4, showed higher freezing tolerance than the wild-type when cold-acclimated. The increase in freezing tolerance was associated with up-regulation of CBF transcription factors and their downstream genes. By contrast, overexpression of At CSP2 resulted in decreased freezing tolerance when cold-acclimated. In addition, late flowering and shorter siliques were observed in the overexpressing lines., At CSP2 negatively regulates freezing tolerance and is partially redundant with its closest paralog, At CSP4. [ABSTRACT FROM AUTHOR]