Genome-wide analyses of Ariadne family genes reveal their involvement in abiotic stress responses in apple

E3 ligases are essential for ubiquitination and play a role in regulating various aspects of eukaryotic life. Ariadne (ARI) proteins, a subfamily of RBR (RING-between-RING) proteins, have been recognized as a new class of RINGfinger E3 ligases. Recent research has shed light on their potential involvement in plants' responses to abiotic stress. However, comprehensive studies on ARI genes in apple (Malus domestica) are still lacking. This study identified ten MdARI genes in the apple genome, and examined intraspecific and interspecific collinearity to explore the evolutionary relationships of ARI family members. Phylogenetic analyses classified MdARIs into two subfamilies (A and B), and by integrating gene structure, conserved motifs, and sequence comparison results, subfamily B was further divided into two subgroups (I and II). Tissue expression analyses revealed varied expression patterns of MdARI genes in different tissues, and subcellular localization showed that MdARI1-1, MdARI1-2, and MdARI9-1 were located in the nucleus, while the other seven MdARIs were distributed throughout the cell. Analyses of promoter cis-elements and expression patterns under cold, salt, and drought treatments indicated the involvement of MdARIs in abiotic stress responses. Several proteins crucial to the plant stress response were predicted to be potential MdARIs-interacting proteins based on the protein interaction network. Additionally, the interaction between UBC11 (E2) and MdARI7-2 was confirmed by a yeast two-hybrid (Y2H) experiment, suggesting that MdARI7-2 may function as an E3. These findings will greatly benefit future research on the role and mechanisms of ARI proteins in apple stress response.