Genome-Wide Identification and Expression Analysis of the NAC Gene Family in , a Typical Mangrove Plant.

The NAC (, , and ) gene family, one of the largest transcription factor families in plants, acts as positive or negative regulators in plant response and adaption to various environmental stresses, including cold stress. Multiple reports on the functional characterization of NAC genes in and other plants are available. However, the function of the NAC genes in the typical woody mangrove () remains poorly understood. Here, a comprehensive analysis of NAC genes in K. obovata was performed with a pluri-disciplinary approach including bioinformatic and molecular analyses. We retrieved a contracted NAC family with 68 genes from the genome, which were unevenly distributed in the chromosomes and classified into ten classes. These NAC genes were differentially and preferentially expressed in different organs, among which, twelve up-regulated and one down-regulated NAC genes were identified. Several stress-related cis-regulatory elements, such as LTR (low-temperature response), STRE (stress response element), ABRE (abscisic acid response element), and WUN (wound-responsive element), were identified in the promoter regions of these 13 NAC genes. The expression patterns of five selected NAC genes (NAC6, NAC15, NAC20, NAC38, and NAC51) were confirmed by qRT-PCR under cold treatment. These results strongly implied the putative important roles of NAC genes in response to chilling and other stresses. Collectively, our findings provide valuable information for further investigations on the function of NAC genes.