Identification of Rice Genes Associated With Enhanced Cold Tolerance by Comparative Transcriptome Analysis With Two Transgenic Rice Plants Overexpressing or , Isolated From Antarctic Flowering Plant .

Few plant species can survive in Antarctica, the harshest environment for living organisms. is the only natural grass species to have adapted to and colonized the maritime Antarctic. To investigate the molecular mechanism of the Antarctic adaptation of this plant, we identified and characterized (), which belongs to monocot CBF group IV. The transcript level of in was markedly increased by cold and dehydration stress. To assess the roles of in plants, we generated a -overexpressing transgenic rice plant () and analyzed its abiotic stress response phenotype. displayed enhanced tolerance to cold stress without growth retardation under any condition compared to wild-type plants. Because the cold-specific phenotype of was similar to that of (Byun et al., 2015), we screened for the genes responsible for the improved cold tolerance in rice by selecting differentially regulated genes in both transgenic rice lines. By comparative transcriptome analysis using RNA-seq, we identified 9 and 15 genes under normal and cold-stress conditions, respectively, as putative downstream targets of the two CBFs. Overall, our results suggest that Antarctic hairgrass mediates the cold-stress response of transgenic rice plants by adjusting the expression levels of a set of stress-responsive genes in transgenic rice plants. Moreover, selected downstream target genes will be useful for genetic engineering to enhance the cold tolerance of cereal plants, including rice.