RhNIRF1‐mediated ubiquitination of RhNAC31 affects drought tolerance by regulating stress‐related genes in Rosa hybrida

Ubiquitin-mediated protein modification by E3 ligases is crucial for plant stress responses. Here, we demonstrate that the RING-type E3 ligase RhNIRF1 physically interacts with and ubiquitinates the NAC-domain transcription factor RhNAC31, establishing a regulatory module that governs drought tolerance in rose (Rosa hybrida). Silencing of RhNAC31 resulted in decreased dehydration tolerance, whereas its overexpression conferred enhanced photosynthetic capacity concomitant with reduced relative oxygen species accumulation. Notably, RhNIRF1 transcript levels were significantly downregulated under drought stress, while RhNAC31 exhibited an opposite trend. In vitro ubiquitination assays confirmed that the RING domain of RhNIRF1 possesses intrinsic E3 ligase activity specifically targeting RhNAC31 for polyubiquitination. Moreover, RhNAC31 directly binds to various stress-related genes in rose, including RhABI1 and RhANAC083, functioning as a transcriptional activator during dehydration responses. Luciferase assays demonstrated that RhNIRF1 accelerates the degradation of RhNAC31, thereby modulating the binding ability of downstream genes. Our findings highlight the RhNIRF1-RhNAC31 module as a novel molecular switch at the post-translational level for improving drought stress tolerance in rose plants.