(Snow Lotus) and Orthologues Involved in Regulating Cold Stress Tolerance in Transgenic .

As with other environmental stresses, cold stress limits plant growth, geographical distribution, and agricultural productivity. (-binding factors/-binding proteins) regulate tolerance to cold/freezing stress across plant species. ICE (inducer of expression) is regarded as the upstream inducer of expression and plays a crucial role as a main regulator of cold acclimation. Snow lotus () is a well-known traditional Chinese herb. This herb is known to have greater tolerance to cold/freezing stress compared to other plants. According to transcriptome datasets, two putative homologous genes, and , were identified in snow lotus. The predicted cDNA contains an ORF of 1506 bp, encoding a protein of 501 amino acids, whereas cDNA has an ORF of 1482 bp, coding for a protein of 493 amino acids. Sequence alignment and structure analysis show SiICE1 and SiICE2 possess a S-rich motif at the N-terminal region, while the conserved ZIP-bHLH domain and ACT domain are at the C-terminus. Both and transcripts were cold-inducible. Subcellular localization and yeast one-hybrid assays revealed that SiICE1 and SiICE2 are transcriptional regulators. Overexpression of () and () in transgenic increased the cold tolerance. In addition, the expression patterns of downstream stress-related genes, , , , , , and , were up-regulated when compared to the wild type. These results thus provide evidence that SiICE1 and SiICE2 function in cold acclimation and this cold/freezing tolerance may be regulated through a CBF-controlling pathway.