Sweet osmanthus ( Osmanthus fragrans ), an evergreen shrub valued for its ornamental and aromatic qualities, is widely used in landscaping and the perfume industry. However, its sensitivity to cold stress limits its cultivation to specific climatic regions, constraining both its horticultural uses and the full exploitation of its genetic resources. In this research, we conducted an identification and examination of the members of RING-type E3 ubiquitin ligase found in sweet osmanthus, discovering a total of 705 members and categorizing them into seven unique RING subtypes. We screened 96 candidate cold stress-responsive genes, of which members of the RING-HC subfamily accounted for the greatest proportion (45/96), suggesting their more significant functional roles under cold stress. Expression profiling and quantitative reverse qRT-PCR analyses revealed that the RING-HC gene OfRNF182-like , was the member whose expression was most strongly induced under cold stress. Using biochemical assays and functional analysis based on transient transformation in sweet osmanthus callus, we demonstrated that OfRNF182-like overexpression reduced cold tolerance, as evidenced by attenuated antioxidant capacity, aggravated oxidative stress, excessive ROS accumulation and OfCBF1, OfDREB2A, OfPOD expression down regulation. Conversely, silencing of OfRNF182-like expression in callus tissue enhanced antioxidant activity and upregulated expression of cold-responsive genes. Interestingly, we found the OfRNF182-like can interact with the cold stress-positive regulator protein OfPP2-B10-like, promoting its degradation under cold stress. Our findings revealed that OfRNF182-like was an important gene that mediated cold tolerance through ROS homeostasis, a previously unrecognized regulatory mechanism, thus identifying it as a potential gene target for breeding cold-tolerant crops.
Wang et al. (Mon,) studied this question.