Heterologous Expression of from L. Promotes Flowering in L.

Methyl-CpG-binding domain (MBD) proteins have diverse molecular and biological functions in plants. Most studies of MBD proteins in plants have focused on the model plant L. Here we cloned from the willow L. by reverse transcription-polymerase chain reaction (RT-PCR) and analyzed the structure of SvMBD5 and its evolutionary relationships with proteins in other species. The coding sequence of is 645 bp long, encoding a 214 amino acid protein with a methyl-CpG-binding domain. SvMBD5 belongs to the same subfamily as AtMBD5 and AtMBD6 from Arabidopsis. Subcellular localization analysis showed that is only expressed in the nucleus. We transformed Arabidopsis plants with a expression construct to examine SvMBD5 function. The Arabidopsis -expressing line flowered earlier than the wild type. In the transgenic plants, the expression of and significantly increased, while the expression of greatly decreased. In addition, heterologously expressing in Arabidopsis significantly inhibited the establishment and maintenance of methylation of and , as well as their expression, and significantly increased the expression of the demethylation-related genes and . Our findings suggest that SvMBD5 participates in the flowering process by regulating the methylation levels of flowering genes, laying the foundation for further studying the role of SvMBD5 in regulating DNA demethylation.