Abstract: Apple ethylene response factor MdERF3 plays an important role in regulating plant growth and fruit ripening. MdERF3 gene was cloned using the‘Gala’apple（Malus × domestica‘Royal Gala’）. The pGBKT7-MdERF3 and PET32a-MdERF3 vectors were constructed. And the transcriptional activation activity of MdERF3 protein and its specific binding ability to the GCC（GCCGCC）and DRE（CCGAC）motifs were analyzed by yeast transformation and electrophoretic mobility shift assays. The yeast transformation test showed that MdERF3 had transcriptional activation activity. The electrophoretic mobility shift assay indicated that MdERF3-HIS fusion proteins directly bound to the GCC and DRE motifs. The pCAMBIA1300-MdERF3 overexpression vector was constructed，and genetically transformed into apple calli and Arabidopsis plants，and transiently transformed into apple leaves. The differences in the anthocyanin and proanthocyanidin accumulation were compared between wild-type and transgenic apple lines. The MdERF3-overexpressing apple calli and Arabidopsis seedlings exhibited increased anthocyanin content compared with wild-type controls and overexpression of MdERF3 promoted the accumulation of proanthocyanidin in apple calli and apple leaves. These results suggest that MdERF3 possesses transcriptional activation activity and binds to GCC and DRE motif and MdERF3 gene plays an important role in regulating anthocyanin and proanthocyanidin accumulation.

Key words: apple, ERF, anthocyanin, proanthocyanidin