Minisymposium 24: Temperature Response

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Abs # M2403: Use of a truncated version of CBF2 to down-regulate the CBF cold response pathway and assess its role in cold acclimation

Presenter:	Doherty, Colleen J.       Contact Presenter
Authors	Doherty, Colleen J. (A) (B)  Gilmour, Sarah J. (A)   Thomashow, Michael F. (A) (C)
Affiliations:	(A): Plant Research Lab Michigan State University (B): Department of Biochemistry and Molecular Biology (C): Department of Crops and Soil Sciences

The CBF/DREB1 family of transcriptional activators plays a major role in the process of cold acclimation, the process whereby certain plants increase in freezing tolerance in response to low non-freezing temperature. Constitutive overexpression of CBF1, 2, or 3 results in constitutive freezing tolerance. Additionally, the metabolome of warm grown CBF overexpressing plants closely resembles that of cold-treated plants. However, transcriptional analysis of cold-treated plants and analysis of several mutants including esk1, ada2a and hos9 has provided evidence for the existence of non-CBF pathways with roles in cold acclimation. Here we further explore the extent to which the CBF cold response pathway contributes to cold acclimation. Arabidopsis plants were transformed with a gene encoding a truncated version of the CBF2 protein, designated CBF2ΔC, placed under control of the strong constitutive CaMV 35S promoter. The CBF2ΔC protein contains the N-terminal amino acids 1 to 135, which includes the AP2 DNA binding domain, but lacks the C-terminal 136 to 216 amino acids, which includes multiple activation domains (Wang et al., 2005). Transcriptional analysis of CBF2ΔC overexpressing plants indicated that a majority of the CBF regulon genes were either no longer cold-induced or were severely down-regulated, yet the plants were able to cold acclimate. These results are consistent with the hypothesis that cold-acclimation pathways independent of the CBF cold regulatory pathway contribute significantly to cold acclimation in Arabidopsis. This work was funded in part by grants to MFT from the National Science Foundation (DBI 0110124), DOE (DE-FG02-91ER20021) and the Michigan Agricultural Experiment Station.