CsWRKY42-CsDREB2B Regulatory Axis Enhances Chilling Tolerance in Tea Plants through Jasmonic Acid Biosynthesis and Antioxidant Defense

Low-temperature (LT) stress severely constrains tea production, yet the molecular mechanisms underlying the integration of jasmonic acid (JA) signaling and antioxidant defense remain elusive. Here, we demonstrate that chilling rapidly activates JA biosynthesis (Allene oxide synthase, CsAOS ) and upregulates the WRKY transcription factor CsWRKY42 in Camellia sinensis . Weighted gene co-expression network analysis (WGCNA) identified the AP2/ERF family gene CsDREB2B as a hub co-expressed with CsWRKY42 and CsAOS . Functional studies revealed that CsDREB2B overexpression enhanced chilling tolerance in Arabidopsis by elevating JA levels, antioxidant activity (SOD, POD, APX), and reducing oxidative damage, while silencing CsDREB2B in tea plants heightened sensitivity. Crucially, CsWRKY42 directly activates CsDREB2B and CsAOS transcription by binding to their promoters, as confirmed by yeast one-hybrid (Y1H), dual-luciferase, and electrophoretic mobility shift assays (EMSAs). Silencing CsWRKY42 suppressed JA accumulation, antioxidant defense, and CsDREB2B expression. Exogenous methyl jasmonate (MeJA) rescued chilling tolerance and upregulated CsDREB2B and CsWRKY42 . We further identified a superior CsDREB2B allele (Chr7:221282042-GG) and developed a dCAPS marker for germplasm screening. Our work elucidates a novel CsWRKY42-CsDREB2B module that synchronizes JA biosynthesis and antioxidant pathways to confer chilling tolerance, providing both mechanistic insights and a molecular tool for breeding cold-resilient tea cultivars.