RrMYB2 Regulates Drought Stress via RrJMJ12-Dependent Epigenetic Modification in Rosa rugosa

Rosa rugosa (R. rugosa), an economically important crop valued for its fragrance and medicinal properties, is highly susceptible to drought stress under open-field cultivation. However, the molecular mechanisms underlying its drought response remain largely unexplored. Here, we identified RrMYB2, a transcription factor that positively regulates drought tolerance in R. rugosa. Overexpressing RrMYB2 in Arabidopsis thaliana and R. rugosa enhanced drought tolerance. Virus-induced silencing of RrMYB2 plants exhibited impaired stomatal closure and reduced drought resistance. RNA-seq of silenced plants revealed that protein phosphatases type 2C (PP2C) genes, including RrHAB1, RrHAB2 and RrABI1, were significantly up-regulated. Biochemical analyses demonstrated that the negative regulation of PP2Cs by RrMYB2 was dependent on its interaction protein RrJMJ12, an H3K27me3 histone demethylase and genetic evidence indicated that RrJMJ12 acts downstream of RrMYB2 to negatively regulate drought resistance. Moreover, the RrMYB2-RrJMJ12 protein complex reduced RrJMJ12 binding to the CTCTGYTY motifs in the promoters of PP2C genes, with this inhibitory effect further enhanced under drought conditions. Collectively, our findings reveal a novel molecular mechanism in which a transcription factor cooperates with an epigenetic modifier to regulate drought tolerance in R. rugosa.