tae-miR399-UBC24 Module Enhances Freezing Tolerance in Winter Wheat via a CBF Signaling Pathway

Although the regulation of Pi homeostasis by miR399 has been studied in various plant species, its underlying molecular mechanism in response to freezing stress is still poorly understood. In this work, we found that the expression of tae-miR399 and its target gene TaUBC24 in the tillering nodes of the strong cold-resistant winter wheat cultivar Dongnongdongmail (Dn1) was not only significantly altered after severe winters but also responsive to short-term freezing stress. TaUBC24 physically interacted with TaICE1. Enhanced freezing tolerance was observed for tae-miR399-overexpressing Arabidopsis lines. Under freezing stress, overexpression of tae-miR399 ultimately decreased the expression of AtUBC24, inhibiting the degradation of AtICE1, which increased the expression of genes involved in the CBF signaling pathway and starch metabolism and promoted the activities of antioxidant enzymes. These results will improve our understanding of the molecular mechanism through which the miR399-UBC24 module plays a cardinal role in regulating plant freezing stress tolerance through mediation of downstream pathways.