Identification and Expression Analysis of C2H2-Type Zinc Finger Protein (C2H2-ZFP) Genes in <i>Bougainvillea</i> in Different Colored Bracts

<i>Bougainvillea</i> spp. possesses vibrantly pigmented bracts that exhibit high ornamental value. Zinc finger proteins (ZFPs), one of the most extensive transcription factor families in plants, are implicated in diverse biological functions, including plant morphogenesis, transcriptional regulation, and responses to abiotic stress. Nevertheless, their regulatory roles in bract pigmentation in <i>Bougainvillea</i> remain unexplored. In the present investigation, 105 <i>BbZFP</i> genes were identified from the <i>Bougainvillea</i> genome via bioinformatic analyses and subsequently categorized into five subgroups according to the quantity and arrangement of their structural domains. Analysis of physicochemical characteristics demonstrated that the BbZFP family encompasses both acidic and basic proteins, all of which are hydrophilic and predominantly classified as unstable proteins. Gene structure analysis revealed that the majority of <i>BbZFP</i> genes comprise between one and five– introns. <i>Cis</i>-regulatory element analysis suggested that <i>BbZFP</i> promoter regions harbor multiple elements associated with abiotic stress responses, hormonal regulation, and light responsiveness, implying their possible participation in these physiological processes. Transcriptomic data analysis revealed distinct expression patterns of <i>BbZFP</i> genes among bracts of different colors. A quantitative real-time polymerase chain reaction (RT-qPCR) further confirmed that <i>Bou_68928</i>, <i>Bou_1096</i>, <i>Bou_4400</i>, and <i>Bou_17631</i> were markedly upregulated in yellow bracts relative to white bracts, suggesting their involvement in flavonoid biosynthesis regulation. Meanwhile, <i>Bou_1096</i> and <i>Bou_17631</i> exhibited markedly elevated expression in red-purple bracts compared to white bracts, potentially regulating betacyanin biosynthesis in <i>Bougainvillea</i>. These findings offer candidate genes for molecular breeding strategies aimed at enhancing floral coloration in <i>Bougainvillea</i>. The next step will involve elucidating the functions of these genes in bract coloration.