Poster: Temperature responses

Abs # 144: Analysis of the regulation of cold-responsive genes that are not part of the CBF regulon

Presenter:	Constan, Diane , jacks282@msu.edu
Authors	Constan, Diane  (A)   Thomashow, Michael F. (A)
Affiliations:	(A): MSU-DOE Plant Research Laboratory, Michigan State University

Many species of plants, including Arabidopsis thaliana, undergo a process known as cold acclimation when exposed to low, nonfreezing temperatures. The molecular changes that occur during cold acclimation allow the plant to survive a subsequent exposure to freezing temperatures. One of the initial steps in cold acclimation is an increase in transcript levels of the CBF (C-repeat binding factor) family of transcription factors. The CBF proteins activate the transcription of several genes, including COR (cold-responsive) genes that are known to be responsible for at least some of the cellular changes occurring during cold acclimation. Microarray experiments using CBF2-overexpressing Arabidopsis plants have indicated that the CBF transcription factors are responsible for activating the expression of over 50% of the genes that are upregulated after exposure to 4 ⁰C for seven days. Although this CBF regulon includes almost all of the most highly upregulated genes (84% of the 25 most highly expressed), there are a few exceptions. We have fused the promoters of two of these genes to the reporter genes luciferase and β-glucuronidase (GUS) in an attempt to learn more about the regulation of these non-CBF regulated, cold-responsive genes. In addition, we are also investigating the regulation of genes that are downregulated in response to low temperatures, almost none of which appear to be controlled by the CBF transcription factors.