CdJACG1 integrates jasmonic acid signaling and CBF pathways to confer cold tolerance in bermudagrass ( Cynodon dactylon )

Cold stress limits the growth and distribution of warm-season grasses such as bermudagrass (Cynodon dactylon). While jasmonic acid (JA) accumulates under cold conditions, the regulatory mechanisms underlying cold adaptation in bermudagrass remain largely unknown. Here, we demonstrate that exogenous methyl jasmonate (MeJA) significantly enhances cold tolerance in bermudagrass. Proteomic analysis identified JA-Activated Cold-responsive Gene 1 (CdJACG1), which was found to accumulate under cold stress in bermudagrass. Overexpression of CdJACG1 enhanced cold tolerance, whereas knockdown of CdJACG1 expression increased cold susceptibility in bermudagrass. Protein-DNA interaction assays revealed that CdMYC2, a positive regulator of cold tolerance, directly binds to the promoter of CdJACG1, suggesting that it directly activates CdJACG1 expression. Both CdJACG1 and CdMYC2 bound to the promoters of allene oxide synthase 2 (CdAOS2) and 12-oxophytodienoate reductase 1 (CdOPR1), thereby amplifying JA accumulation. Heterologous expression of CdAOS2 or CdOPR1 in Arabidopsis thaliana enhanced cold tolerance. Beyond its role in JA signaling, CdJACG1 integrates with the C-repeat binding factor (CBF)-mediated cold signaling pathway by directly activating the expression of dehydration-responsive element-binding protein 1.3 (CdDREB1.3), a known positive regulator of plant cold tolerance. Collectively, our findings reveal a potential regulatory module involving CdJACG1 and CBF/DREB1. This module is likely directly regulated by CdMYC2 and synergistically integrates JA signaling with the CBF/DREB1-dependent pathway to enhance cold tolerance in bermudagrass. Our work thus provides crucial insights for molecular breeding of cold-tolerant warm-season grasses and crops.