Characterization of the NAC gene family in ‘Fengdan’ peony (Paeonia ostii) insights into the evolution and expression patterns under abiotic stresses and ABA treatment

In this study, a total of 82 NAC transcription factors (TFs) were identified in the 'Fengdan' peony genome, with the uneven anchorage of 78 <i>PoNAC</i> genes on 5 chromosomes, whereas only 4 <i>PoNAC</i> genes were found to be located on unanchored scaffolds. Through the phylogenetic analysis, 66 <i>PoNAC</i> genes were classified into 15 distinct subfamilies. The gene structure analysis revealed the variation in the number of exons from 0 to 14. Moreover, the motif analysis indicated that the identified PoNAC TFs possessed conserved NAC domains and motifs. The duplication events of <i>PoNAC</i> genes included whole-genome duplications (WGDs) or segmental duplications for 14 pairs, tandem duplications for 2 pairs, and proximal duplications for 3 pairs. GO analysis results suggested that the functions of <i>PoNAC</i> genes were mostly concentrated in the "biological process" GO category. Additionally, the analysis of the expression profiles of <i>PoNAC</i> genes in different plant organs revealed that only 45 genes were expressed in various tissues, some of them exhibited tissue-specific expression related to plant growth and development. RT-qPCR experiments demonstrated the responses of 8 genes from the ATAF and NAP subfamilies to ABA, heat and drought, suggesting that they may serve as important regulatory factor.