Genome-wide identification and cold stress-induced expression analysis of the CBF gene family in Liriodendron chinense

Cold-resistance pathways that operate in model plants such as Arabidopsis thaliana and Oryza sativa have been studied extensively. It has been found that CBF genes play an important role in plant cold resistance. Liriodendron chinense , a tree known for its graceful tree shape and widely spread in south China, has weak cold tolerance. However, little is known about its response to cold. To further study the function of L. chinense CBF gene family, we started by characterizing all members of this gene family in the L. chinense genome and their expression profiling. Phylogenetic analysis found that 14 CBF genes in L. chinense are more closely related to their homologues in woody plants and A. thaliana than those in O. sativa . Cis-acting elements and GO analysis showed that some LcCBF genes participated in the biological process of cold stress response. The transcriptomic and RT-qPCR data showed that most of LcCBF genes displayed an initially increasing and subsequently decreasing trend during cold stress course and the expression profile of each member was different. Some LcCBF genes exhibited a different abundance in callus, root, stem and leaf tissues. The structure and expression characteristics of LcCBF genes imply that they may have similar and different functions in response to cold stress conditions. The identification and analysis of LcCBF gene family have laid the foundation for future studies into L. chinense cold stress mechanisms and for the cultivation of cold-resistance cultivars.