Rubus idaeus is one of the primary cultivated species of raspberries, renowned for its appealing color, distinctive flavor and numerous health benefits. WIP proteins, which contain three conserved amino acids (W: Tryptophan, I: Isoleucine, P: Proline) and four zinc finger motifs in a highly conserved C-terminal region, are members of the A1d subgroup of C2H2 zinc finger proteins. Drought is one of the main limiting factors of plant growth and development, which restricts the cultivation and utilization of raspberry in northwest China. In this study, to obtain candidate genes for drought resistance, we identified key related genes, RiWIPs, from R. idaeus and analyzed their bioinformation and tissue stress response expression to drought. We found that there are three RiWIPs in R. idaeus and they are located on chromosomes 3, 4 and 6 of R. idaeus, respectively. The open reading frames (ORFs) of the RiWIPs ranged from 870 to 1056 bp in length, encoding 289 to 372 amino acid residues. The proteins were highly conserved and feature diverse conserved motifs. The promoters of the RiWIPs contained abundant cis-elements related to growth, development and stress response. Tissue-specific expression analysis revealed that the RiWIPs were expressed in the leaves, stems and roots of both drought-susceptible and drought-tolerant cultivars, except for RiWIP2, which was only expressed in the roots of the drought-tolerant one. Under drought stress, the transcriptional activity of the RiWIPs was increased to different degrees with specificity in the leaves, stems and roots. Our study demonstrated the role of WIP genes in raspberry drought response and provided a marker gene, RiWIP2, for drought resistance and candidate genes for subsequent drought-resistant breeding of R. idaeus.

Drought significantly limits the productivity and quality of Juglans regia, yet the regulatory mechanisms governing drought tolerance in this economically vital nut tree remain largely elusive. Here, we report that the WRKY transcription factor JrTTG2 acts as a central hub in the walnut drought response by integrating transcriptional and protein-interaction networks. We identified JrTTG2 as a hypersensitive early-response gene, exhibiting a robust 333-fold induction in walnut roots under drought stress. Ectopic expression of JrTTG2 in Arabidopsis and poplar significantly enhanced drought tolerance, primarily by maintaining root architecture, increasing biomass, and reducing oxidative damage. Conversely, RNAi-mediated silencing of PagTTG2 in poplar led to stunted root systems and compromised antioxidant defense under water deficit. Transcriptomic and molecular analyses revealed that JrTTG2 directly binds to the W-box in the promoter of the JrGSTU8 gene to activate its transcription, thereby facilitating ROS scavenging. Furthermore, yeast two-hybrid and BiFC assays demonstrated that JrTTG2 physically interacts with the vesicle trafficking protein JrEPSIN1. Both JrGSTU8 and JrEPSIN1 showed highly synchronized induction with JrTTG2 in walnut roots during drought. Taken together, this study provides a novel dimension to the molecular mechanisms of woody plant adaptation and offers a promising candidate gene for breeding drought-tolerant walnut varieties.