
R2R3‐MYB transcription factor MdMYB23 is involved in the cold tolerance and proanthocyanidin accumulation in apple
Cold stress severely affects plant growth and yield. C‐repeat binding factors (CBFs) play important roles in the response to cold stress. In the present study, we identified an R2R3‐MYB transcription factor (TF) MdMYB23 from apple (Malus × domestic) using
transcriptome analyses, which was notably induced in response to cold stress. Transgenic apple calli and Arabidopsis with overexpression of MdMYB23 exhibited increased cold tolerance. Electrophoretic mobility shift assay (EMSA) and transient expression assays indicated that MdMYB23
directly bound to the promoters of MdCBF1 and MdCBF2 and activated their expression. MdMYB23 interacted with the promoter of MdANR, a key modulator of proanthocyanidin biosynthesis, and activated its expression to promote proanthocyanidin accumulation and reactive oxygen
species (ROS) scavenging. MdBT2 was identified as an MdMYB23‐interacting protein using yeast two‐hybrid (Y2H), pull‐down, and bimolecular fluorescence complementation (BiFC) assays. MdBT2 repressed cold tolerance and proanthocyanidin accumulation by promoting the degradation
of MdMYB23 protein. Our findings shed light on the functions of MYB TFs and underlying mechanism in the modulation of plant cold tolerance.
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Keywords: MdBT2; MdMYB23; cold tolerance; proanthocyanidin; reactive oxygen species
Document Type: Research Article
Publication date: November 1, 2018