Genome-wide identification of the CmPLATZ gene family and its role in cold acclimation and overwintering in Chrysanthemum morifolium

Chrysanthemum (Chrysanthemum morifolium) is a globally important ornamental and economic crop that is susceptible to cold stress, which can present challenges for its large-scale cultivation. Plant AT-rich sequence and zinc-binding (PLATZ) transcription factors are key regulators of plant perception and response to cold and other abiotic stresses; however, the role of these factors in the cold tolerance of chrysanthemum remains unclear. In this study, we identified 41 CmPLATZ genes through a genome-wide analysis. We systematically investigated the structural features, chromosomal localization, phylogenetic relationships, promoter cis-acting elements, and cold-responsive transcriptional profiles of these genes. Additionally, the tissue-specific expression and cold-inducible patterns of key members were analyzed in 11 chrysanthemum accessions with divergent cold tolerance. The 41 CmPLATZ genes were distributed across 21 chromosomes and clustered into six groups. The expansion of CmPLATZ was primarily driven by whole-genome duplication (WGD) events. Ka/Ks analysis indicated that the duplicated genes have been subjected to purifying selection, which resulted in limited functional divergence. Synteny analysis revealed that the evolutionary relationships of CmPLATZ genes are more complex than those of PLATZ gene families in the related species C. makinoi and C. seticuspe. Based on the analysis of promoter elements and transcriptome profiling, we observed that multiple CmPLATZ members respond to low-temperature stress and we identified CmPLATZ1a and CmPLATZ4a as key candidate regulators. Subcellular localization experiments confirmed the nuclear localization of these proteins, and heterologous functional validation demonstrated that overexpression of CmPLATZ1a in Arabidopsis significantly enhanced cold tolerance, suggesting the potential involvement of this gene in regulating conserved cold-response pathways. This study provides the first genome-wide characterization of the CmPLATZ family, offering new insights into the cold-response regulatory network of chrysanthemum, and providing a theoretical basis and candidate gene resources for the extension of the cultivation range.