The CPP gene family comprises transcription factor genes containing a conserved CRC domain, which is mainly involved in plant development and evolution. Although CPP genes have been widely studied in many plants, little is known about them in woody plants, especially in the endangered species Phoebe bournei (Hemsl.). In the genome of Phoebe bournei, we identified 11 PbCPP genes (PbCPP1-PbCPP11) distributed on four chromosomes, with large differences in the number of amino acids. They encode both acidic and alkaline proteins. A phylogenetic analysis showed that these PbCPP genes can be divided into three subfamilies, A, B, and C, which contain seven, two, and two genes, respectively. Through an interspecific collinearity analysis, we identified homologous PbCPP genes. A promoter cis-acting element analysis revealed that PbCPPs contain a variety of elements that respond to plant hormones, stress signals, and light and play a role in growth and development, and most PbCPP genes (except PbCPP3 and PbCPP8) contain MYB binding site elements that regulate drought-induced stress responses, indicating that they play an important role in plant drought resistance. An expression analysis showed that PbCPP3 and PbCPP4 expression was high in the roots and stems and lower in the leaves, whereas the expression of most of the other genes was low in the roots, stems, and leaves. In addition, six representative PbCPP genes were detected using qRT-PCR. The results show significant differences in the expression of PbCPP genes under abiotic stress conditions (drought, cold, and salt), indicating that they play an important role in stress responses. This study preliminarily verified the role of the PbCPP gene family in different abiotic stress responses, which is of great significance for understanding its mechanism in plant growth and development and stress adaptation.

Phoebe bournei is a second-class endangered and protected species unique to China, and it holds significant ecological and economic value. DNA binding one zinc finger (Dof) transcription factors are plant-specific regulators. Numerous studies have demonstrated that Dof genes are involved in plant growth, development and responses to abiotic stress. In this study, we identified and analyzed 34 PbDof gene members at the whole-genome level. The results indicated that the 34 PbDof genes were unevenly distributed across 12 chromosomes. We utilized the Dof genes from Arabidopsis thaliana and P. bournei to construct a phylogenetic tree and categorized these genes into eight subgroups. In the collinearity analysis, there were 16 homologous gene pairs between AtDof and PbDof and nine homologous gene pairs between ZmDof and PbDof. We conducted a cis-acting element analysis and found that cis-acting elements involved in light response were the most abundant in PbDof genes. Through SSR site prediction, we analyzed that the evolution level of Dof genes is low. Additionally, we assessed the expression profiles of eight PbDof genes under high temperature, drought, and light stress using qRT-PCR. In particular, PbDof08 and PbDof16 are significantly upregulated under the three stresses. This study provides foundational information for PbDof genes and offers new insights for further research on the mechanism of Dof transcription factors responding to stress, as well as the adaptation of P. bournei to environmental changes.

Auxin response factors (ARFs) are pivotal transcription factors that regulate plant growth, development, and stress responses. Yet, the genomic characteristics and functions of ARFs in Phoebe bournei remain undefined. In this study, 25 PbARF genes were identified for the first time across the entire genome of P. bournei. Phylogenetic analysis categorized these genes into five subfamilies, with members of each subfamily displaying similar conserved motifs and gene structures. Notably, Classes III and V contained the largest number of members. Collinearity analysis suggested that segmental duplication events were the primary drivers of PbARF gene family expansion. Structural analysis revealed that all PbARF genes possess a conserved B3 binding domain and an auxin response element, while additional motifs varied among different classes. Promoter cis-acting element analysis revealed that PbARF genes are extensively involved in hormonal responses—particularly to abscisic acid and jasmonic acid and abiotic stresses—as well as abiotic stresses, including heat, drought, light, and dark. Tissue-specific expression analysis showed that PbARF25, PbARF23, PbARF19, PbARF22, and PbARF20 genes (class III), and PbARF18 and PbARF11 genes (class V) consistently exhibited high expression levels in the five tissues. In addition, five representative PbARF genes were analyzed using qRT-PCR. The results demonstrated significant differences in the expression of PbARF genes under various abiotic stress conditions (drought, salt stress, light, and dark), indicating their important roles in stress response. This study laid a foundation for elucidating the molecular evolution mechanism of ARF genes in P. bournei and for determining the candidate genes for stress-resistance breeding.

The TCP transcription factor (TF) family is a vital set of plant-specific regulators involved in plant growth, development, and responses to environmental stresses. Despite the extensive research on TCP transcription factors in numerous plant species, the functions they fulfill in Betula platyphylla are still not well understood. In this study, 21 BpTCP genes were identified via genome-wide analysis. Bioinformatics analysis was used to examine the physicochemical properties of these transcription factors, including molecular weight, isoelectric point, chromosomal distribution, and predicted subcellular localization. We expected that most BpTCP transcription factors would be located in the nucleus. Collinearity analysis revealed that gene fragment duplication events played a major role in the evolutionary expansion and diversification of the BpTCP gene family. Promoter analysis identified diverse cis-acting elements in BpTCP, suggesting that they play a role in stress responses, hormonal regulation, and plant growth and development. qRT-PCR analysis showed that BpTCP genes displayed tissue-specific expression patterns in the roots, stems, and leaves, displaying remarkable differences in expression levels when subjected to abiotic stresses, including drought and high- and low-temperature conditions. Notably, BpTCP17 and BpTCP18 showed markedly higher expression levels under multiple stress conditions. Subcellular localization experiments confirmed that both BpTCP17 and BpTCP18 localize in the nucleus, consistent with bioinformatic predictions. These findings emphasize the potential roles of BpTCP17 and BpTCP18 in mediating abiotic stress responses, highlighting their potential as candidate genes for improving stress tolerance in B. platyphylla.

BES1 (BRI1 EMS SUPPRESSOR 1) is a critical transcription factor involved in plant growth, development, and stress responses. Although BES1 genes have been characterized in several species, their roles in longan (Dimocarpus longan Lour.) remain unclear. This study identified and analyzed eight BES1 genes in the longan genome. Phylogenetic analysis classified these genes into four subgroups (I-IV), with conserved motifs and intron–exon structures indicating potential functional similarities within subgroups. Cis-element analysis revealed that the promoters of DlBES1 genes contain numerous hormone-related elements, including ABRE, TGACG, and TCA motifs, suggesting their involvement in hormonal signaling and stress responses. Expression profiling showed differential expression patterns of DlBES1 genes across nine tissues, with notable up-regulation in roots and seeds. Additionally, DlBES1 genes exhibited distinct expression trends under varying temperatures and in response to IAA treatment, indicating potential roles in temperature stress adaptation and hormone signaling. These findings provide novel insights into the regulatory mechanisms of BES1 genes in longan and highlight their potential significance in stress tolerance and growth regulation.