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The F-box family exists in a wide variety of plants and plays an extremely important role in plant growth, development and stress responses. However, systematic studies of F-box family have not been reported in populus trichocarpa. In the present study, 245 PtrFBX proteins in total were identified, and a phylogenetic tree was constructed on the basis of their C-terminal conserved domains, which was divided into 16 groups (A–P). F-box proteins were located in 19 chromosomes and six scaffolds, and segmental duplication was main force for the evolution of the F-box family in poplar. Collinearity analysis was conducted between poplar and other species including Arabidopsis thaliana, Glycine max, Anemone vitifolia Buch, Oryza sativa and Zea mays, which indicated that poplar has a relatively close relationship with G. max. The promoter regions of PtrFBX genes mainly contain two kinds of cis-elements, including hormone-responsive elements and stress-related elements. Transcriptome analysis indicated that there were 82 differentially expressed PtrFBX genes (DEGs), among which 64 DEGs were in the roots, 17 in the leaves and 26 in the stems. In addition, a co-expression network analysis of four representative PtrFBX genes indicated that their co-expression gene sets were mainly involved in abiotic stress responses and complex physiological processes. Using bioinformatic methods, we explored the structure, evolution and expression pattern of F-box genes in poplar, which provided clues to the molecular function of F-box family members and the screening of salt-tolerant PtrFBX genes. [ABSTRACT FROM AUTHOR]

Extreme environments, especially drought and high salt conditions, seriously affect plant growth and development. Ethylene-responsive factor (ERF) transcription factors play an important role in salt stress response. In this study, a significantly upregulated ERF gene was identified in 84K (Populus alba × P. glandulosa), which was named PagERF072. PagERF072 was confirmed to be a nuclear-localized protein. The results of yeast two-hybrid (Y2H) assay showed that PagERF072 protein exhibited no self-activating activity, and yeast one-hybrid (Y1H) demonstrated that PagERF072 could specifically bind to GCC-box element. Under salt stress, the transgenic poplar lines overexpressing PagERF072 showed improved salt tolerance. The activities of peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) in transgenic poplars were significantly increased relative to those of wild-type (WT) plants, whereas malondialdehyde (MDA) content showed an opposite trend. In addition, reactive oxygen species (ROS) was significantly reduced, and the expression levels of POD- and SOD-related genes were significantly increased in transgenic poplars under salt stress compared with WT. All results indicate that overexpression of the PagERF072 gene can improve the salt tolerance of transgenic poplars. [ABSTRACT FROM AUTHOR]

The MYB transcription factor (TF) family, widely recognized for its involvement in multiple biological processes, holds a significant position among plant TF families due to its substantial size. The R2R3-MYB TF has been extensively studied and known for its pivotal role in regulating the synthesis of anthocyanin, lignin, and secondary wall components in plants. However, there is currently limited information available regarding the function of R2R3-MYB genes in response to salt stress specifically in poplar. Here, we focused on a specific R2R3-MYB gene, PagMYB73 , which belongs to the 84K poplar (Populus alba × P. glandulosa) species. We aimed to investigate the role of PagMYB73 in the regulatory mechanisms involved in salt stress response. PagMYB73 showed strong induction in leaves under salt stress conditions. Transgenic poplar plants overexpressing PagMYB73 exhibited enhanced salt tolerance, while suppression of the gene resulted in increased sensitivity to high salt levels. PagMYB73 can regulate the expression of several stress-related genes, including PagGSTU19 , PagLEA51, PagSODs , PagPODs , and PagP5CS2. It achieves this by binding to the promoter regions of these genes that orchestrate adaptive responses to salt stress by modulating the osmotic balance and reducing the levels of reactive oxygen species (ROS). Indeed, overexpression of PagGSTU19 and PagLEA51 has been shown to enhance the salt tolerance of poplar. In conclusion, PagMYB73 regulates the expression of stress-related genes to improve ROS scavenging ability and osmotic maintenance, thereby improving the salt tolerance of the transgenic poplar. [Display omitted] • Overexpression of PagMYB73 can improve salt tolerance in poplar. • PagMYB73 is crucial for reactive oxygen species scavenging and osmotic maintenance. • PagMYB73 can directly regulate the expression of PagGSTU19 and PagLEA51. • Overexpression of PagGSTU19 and PagLEA51 can enhance salt tolerance of poplar. [ABSTRACT FROM AUTHOR]