Chalcone Synthase (CHS) plays a vital role in flavonoid synthesis, influencing plant growth, development, and responses to both biotic and abiotic stress. In this study, 11 CHS genes were identified in Poncirus trifoliata using bioinformatics methods, with their distribution across five chromosomes and unassigned contigs. Each gene contains 2–3 exons and 3–8 conserved motifs. In silico prediction suggested that the PtrCHS proteins are localized in the cytoplasm. PtrCHS9 and PtrCHS11 share identical protein tertiary structures. Phylogenetic analysis classified the CHS family members into four subgroups. Synteny analysis revealed one set of collinear gene pairs within Poncirus trifoliata. Between Poncirus trifoliata and Arabidopsis thaliana, two sets of collinear gene pairs were identified, while one such set was found between Poncirus trifoliata and Oryza sativa. Promoter element analysis showed the presence of various hormone response and stress response elements within PtrCHS promoters. RNA-Seq data demonstrated tissue-specific expression patterns of PtrCHSs. RT-qPCR results indicated that all CHS genes, except PtrCHS11, respond to salt stress with dynamic, member-specific patterns. Additionally, four PtrCHSs (PtrCHS3, PtrCHS5, PtrCHS7, and PtrCHS10) were significantly upregulated in response to cold treatment. Notably, PtrCHS7 and PtrCHS10 maintained high expression levels at both 6 and 12 h, implying they may be key players in cold stress response in Poncirus trifoliata. Clones of PtrCHS7 and PtrCHS10 were obtained, and overexpression vectors were constructed in preparation for gene transformation. Overall, this study provides a solid foundation for future research into the functions of the PtrCHSs.

Acyl-CoA-binding proteins (ACBPs) are essential lipid carrier proteins involved in plant lipid metabolism. However, the systematic identification and expression profiles of the ACBP gene family in citrus species remain poorly understood. Here, Citrus sinensis and Poncirus trifoliata were chosen as model species to examine the biological properties of citrus ACBPs. Using bioinformatics methods, five ACBP gene members were found in each species and named CsACBPs and PtrACBPs, respectively. All obtained ACBP members were divided into four subfamilies based on conserved domains and amino acid sequences. CsACBP and PtrACBP genes exhibited structural variation in motifs and exons. The predicted protein structures of CsACBPs and PtrACBPs exhibited conservation between the two species while displaying distinct variation within each species. Collinearity analysis showed one intraspecific pairing relationship in each of the two citrus species. Furthermore, there were more collinear couplings between citrus species and Arabidopsis thaliana but none between citrus species and Oryza sativa (rice). Notably, the analysis of cis-acting elements in ACBP gene promoters identified a number of motifs associated with light, abiotic stresses, and phytohormones. Expression profiling confirmed tissue-specific expression patterns of CsACBP1~5 and PtrACBP1~5. RT-qPCR analysis revealed that all CsACBP and PtrACBP genes responded to cold and salt stresses, though the magnitude of their responses varied significantly. Specially, although PtrACBP5 did not respond to low temperatures as rapidly as other members, its expression level increased significantly after 24 h of low-temperature treatment. Protein–protein interaction (PPI) network predictions indicated tight associations among four of the five CsACBPs, with CsACBP5 excluded from these interactions. Moreover, CsACBP1, CsACBP2, and CsACBP3 were predicted to be potential targets of csi-miR3952, csi-miR396a, and csi-miR477b, respectively. Overall, our research provides a solid foundation for further investigations into the biological functions and regulatory mechanisms of ACBP genes in citrus growth, development, and stress adaptation.

Plant respiratory burst oxidase homolog (Rboh) genes are integral to the production of reactive oxygen species (ROS) and the regulation of stress responses. Here, bioinformatic techniques were employed to identify eight PgRboh genes (PgRbohA–H) in the genome of pomegranate (Punica granatum L.) and conduct a systematic analysis of this family. The findings showed that all PgRbohs proteins possess characteristic NADPH oxidase domains and are predicted to be localized on the cell membrane. Experimental verification confirmed the membrane localization of PgRbohD and PgRbohE proteins. Phylogenetic analysis categorized the PgRbohs proteins into six distinct groups, suggesting potential functional divergence among these groups. Promoter analysis revealed a significant presence of cis-acting elements responsive to low-temperature and methyl jasmonate (MeJA). The expression of PgRboh genes was found to be tissue-specific. Additionally, real-time PCR (RT-qPCR) was used to analyze expression patterns in response to low-temperature stress that involves multiple PgRboh genes in the cold response process. Overall, our results lay an important foundation for subsequent studies on the cold resistance function of pomegranate Rboh genes and provides new ideas for the breeding of new cold-resistant pomegranate varieties.