Genome-Wide Analysis of NAC Gene Family in Betula pendula

NACs (NAM, ATAF1/2, and CUC2) are plant-specific transcription factors that play diverse roles in various plant developmental processes. In this study, we identified the NAC gene family in birch (Betula pendula) and further analyzed the function of BpNACs. Phylogenetic analysis reveals that the 114 BpNACs can be divided into seven subfamilies. We investigated the expression levels of these BpNACs in different tissues of birch including roots, xylem, leaves, and flowers, and the results showed that the BpNACs seem to be expressed higher in xylem and roots than leaves and flowers. In addition to tissue-specific expression analysis, we investigated the expression of BpNACs under low-temperature stress. A total of 21 BpNACs were differentially expressed under low-temperature stress, of which 17 were up-regulated, and four were down-regulated. Using the gene expression data, we reconstructed the gene co-expression network for the 21 low-temperature-responsive BpNACs. In conclusion, our results provide insight into the evolution of NAC genes in the B. pendula genome, and provide a basis for understanding the molecular mechanism for BpNAC-mediated cold responses in birch.