The U-box E3 ubiquitin ligase (PUB) gene family plays an important role in regulating plant responses to abiotic stress. Poncirus trifoliata (trifoliate orange), a citrus rootstock with notable cold, drought, and salt tolerance, serves as an excellent model for studying stress-responsive genes. In this study, a total of 47 PUB genes (PtrPUBs) were identified in the trifoliate orange genome. Chromosomal distribution analysis indicated that PtrPUB genes were unevenly distributed across nine trifoliate orange chromosomes. Phylogenetic tree analysis indicated that 170 PUB proteins from trifoliate orange, Arabidopsis thaliana, and tomato were clustered into five subfamilies. Gene structure, conserved domain, and motif analyses revealed diverse exon–intron and motif organizations of PtrPUB genes, suggesting potential functional differentiation among PtrPUBs. Cis-acting analysis indicated that the promoters of PtrPUB genes harbor elements related to hormone signaling (ABA, MeJA), drought stress, and low-temperature responses. Transcriptomic data and qRT-PCR results suggested that PtrPUB genes are responsive to ABA and dehydration treatments. This study provides a foundation for understanding the functional roles of PUB genes in trifoliate orange and offers insights for improving stress tolerance in citrus breeding programs.

Heterotrimeric G-proteins are key signal transduction mediators involved in regulating plant growth and development, and responses to various stress in plants. G-proteins are extensively investigated in model plants, such as Arabidopsis thaliana and Oryza sativa. However, the identification and function of G-proteins in woody species, particularly Populus, remain largely unexplored. In this study, we performed a genome-wide identification and comprehensive analysis of the G-protein gene family in poplar, aiming to reveal their evolutionary history, structural diversity and potential function roles. As a result, a total of 27 G-protein genes were identified in the poplar genome, including 18 Gα, 4 Gβ and 5 Gγ subunits. Phylogenetic analysis indicated that 27 G-protein genes were divided into three subgroups. Gene structure, conserved domain and motifs indicated the conserved nature of G-protein at sequence and structure. In addition, synteny analysis revealed that whole-genome duplication events contributing to the expansion of the G-protein gene family in poplar. Cis-regulatory element analysis indicated that many G-protein genes in poplar contain hormone and stress related motifs, suggesting that G-protein genes are involved in environmental adaptation. Expression profiling analysis demonstrated that G-protein genes exhibited tissue-specific expression and stress-responsive expression patterns, highlighting their potential regulatory roles in growth and development and responses to biotic and abiotic stresses. This study provides valuable insights into the poplar G-protein gene family and lays the foundation for further functional analyses, contributing to improving stress tolerance in forestry species.