Cold Shock Domain Protein 3 Regulates Freezing Tolerance in Arabidopsis thaliana

Abstract

In response to cold, Escherichia coli produces cold shock proteins (CSPs) that have essential roles in cold adaptation as RNA chaperones. Here, we demonstrate that Arabidopsis cold shock domain protein 3 (AtCSP3), which shares a cold shock domain with bacterial CSPs, is involved in the acquisition of freezing tolerance in plants. AtCSP3 complemented a cold-sensitive phenotype of the E. coli CSP quadruple mutant and displayed nucleic acid duplex melting activity, suggesting that AtCSP3 also functions as an RNA chaperone. Promoter-GUS transgenic plants revealed tissue-specific expression of AtCSP3 in shoot and root apical regions. When exposed to low temperature, GUS activity was extensively induced in a broader region of the roots. In transgenic plants expressing an AtCSP3-GFP fusion, GFP signals were detected in both the nucleus and cytoplasm. An AtCSP3 knock-out mutant (atcsp3-2) was sensitive to freezing compared with wild-type plants under non-acclimated and cold-acclimated conditions, whereas expression of C-repeatbinding factors and their downstream genes during cold acclimation was not altered in the atcsp3-2 mutant. Overexpression of AtCSP3 in transgenic plants conferred enhanced freezing tolerance over wild-type plants. Together, the data demonstrated an essential role of RNA chaperones for cold adaptation in higher plants.

Comparison of structure, function and regulation of plant cold shock domain proteins to bacterial and animal cold shock domain proteins

“…Comparative sequence analysis revealed multiple discrepancies in cis-element regions which may impart transcriptional control over this gene locus (79). Using transgenic overexpression lines for the well characterized abiotic stress related CBF/DREB transcription factors, we confirmed that AtCSP3 (At2g17870), which is a regulator of cold acclimation (33), is targeted by the CBF3/DREB1A transcription factor (unpublished results).…”

“…In the case of plant CSPs, no evidence has been produced to suggest that they may function to directly affect transcription. However, CSPs from wheat and Arabidopsis are localized to the nucleus (30,(32)(33)(34)53), which indirectly supports a putative functional role related to transcription.…”

“…Expression studies revealed that some Arabidopsis CSP transcripts are also increased upon cold stress treatment, indicating a potential role in cold adaptation (19,31,32). Arabidopsis thaliana cold shock domain proteins (AtCSPs) promote cold adaptation in bacteria (31)(32)(33)(34). Using functional approaches, AtCSPs were shown to play an important role under low temperature stress conditions in planta (33,34).…”

“…Arabidopsis thaliana cold shock domain proteins (AtCSPs) promote cold adaptation in bacteria (31)(32)(33)(34). Using functional approaches, AtCSPs were shown to play an important role under low temperature stress conditions in planta (33,34). In rice, a plant which cannot acclimate to cold conditions, cold shock domain proteins were not induced in response to low temperature stress.…”

An RNA chaperone, AtCSP2, negatively regulates salt stress tolerance

“…Compared with wild type, a knockout mutant of AtCSP3 is more sensitive to freezing, drought, and salt stresses. 26,27 Conversely, overexpression of AtCSP3 confers enhanced stress tolerance. 26,27 AtCSP3 regulates the expression of abiotic stress responsive genes, but the functions of these genes are mostly unknown.…”