Abstract
Low temperature regulates gene expression in bacteria, yeast, and animals as well as in plants. However, the signal transduction cascades mediating the low temperature responses are not well understood in any organism. To identify components in low temperature signaling genetically, we isolated
Arabidopsis thaliana
mutants in which cold-responsive genes are no longer induced by low temperatures. One of these mutations,
los1–1
, specifically blocks low temperature-induced transcription of cold-responsive genes. Surprisingly, cold-induced expression of the early response transcriptional activators, C-repeat/dehydration responsive element binding factors (CBF/DREB1s), is enhanced by the
los1–1
mutation. The
los1–1
mutation also reduces the capacity of plants to develop freezing tolerance but does not impair the vernalization response. Genetic analysis indicated that
los1–1
is a recessive mutation in a single nuclear gene. The
LOS1
gene encodes a translation elongation factor 2-like protein. Protein labeling studies show that new protein synthesis is blocked in
los1–1
mutant plants specifically in the cold. These results reveal a critical role of new protein synthesis in the proper transduction of low temperature signals. Our results also suggest that cold-induced transcription of
CBF/DREB1
s is feedback inhibited by their gene products or by products of their downstream target genes.