DEA1, a circadian- and cold-regulated tomato gene, protects yeast cells from freezing death.

Cold and freezing damage to plants can be mitigated by inducible factors during an acclimation period. DEA1 is a circadian-regulated tomato (Solanum lycopersicum) gene with sequence similarity to EARLI1, an Arabidopsis thaliana gene that confers cold protection. To investigate whether DEA1 was responsive to environmental variables such as cold, cold-treated tomatoes were analyzed for DEA1 expression. DEA1 transcript accumulated in response to cold, and the rapidity of the cold-induced transcript accumulation was regulated by the circadian rhythm. To test whether DEA1 could protect cells from freezing damage, we transformed the yeast, Pichia pastoris, with an inducible DEA1 construct. Yeast cells transformed with the gene survived freezing at a significantly higher rate than control strains and a strain expressing the LacZ gene. Transgenic tomato plants over-expressing or knocking down DEA1 transcript levels did not have an altered phenotype with respect to cold- or pathogen-susceptibility relative to control plants.