Abstract

In Arabidopsis the CBF pathway has an important role in freezing tolerance. The transcriptional activators CBF1, CBF2 and CBF3 are quickly induced by cold followed by expression of the CBF regulon, nearly 100 genes, resulting in an increase in freezing tolerance. The freezing sensitive Solanum tuberosum has 5 CBF genes; its freezing tolerant wild relative, Solanum commersonii has 4. Two CBFs of both species, CBF1 and CBF4, are cold-induced. We are determining the makeup of the CBF and other cold response pathways of S. commersonii and S. tuberosum. We have identified that these species share 50 to 70% of their cold transcriptomes. Further, the CBF regulons of these species comprise about 300 clones, with an overlap of only about 80 clones. Identification of putative orthologous groups of genes between Arabidopsis and S. tuberosum allowed us to compare their cold- and CBF-responsive genes. Preliminary results suggest there is little conservation between the cold-regulated genes of Arabidopsis and the two Solanum species. However, 15 groups of putative orthologous genes were identified as being cold-regulated in both S. commersonii and Arabidopsis, but apparently not in S. tuberosum. Whether these genes contribute significantly to differences in freezing tolerance between these plants, remains to be determined.