Transcription factor PagERF110 inhibits xylem differentiation by direct regulating PagXND1d in poplar

Ethylene-responsive factor (ERF) transcription factors (TFs) play an important role in plant development and growth, while their underlying function in xylem development is not very clear in poplar. In this study, a nucleus-located ERF gene, PagERF110 was isolated from Populus alba × P. glandulosa, which displayed a relatively high expression in phloem and xylem. The transgenic poplar overexpressing PagERF110 showed less secondary xylem deposition than wild-type (WT). And the contents of cellulose, xylose and lignin in the cell wall of transgenic lines were less than those of WT. Transcriptome analyses showed that PagERF110 could activate the expression of a few downstream genes related to secondary cell wall (SCW) formation. Among them, poplar NAC domain XYLEM NAC DOMAIN1 (PagXND1d) is a key downstream gene, whose overexpression inhibits the development of secondary xylem. And the evidences from yeast one-hybrid (Y1H), luciferase assay and chromatin immunoprecipitation (ChIP) assay all proved that PagERF110 directly regulates the expression of PagXND1d, and overexpression PagXND1d reduces secondary xylem deposition in transgenic poplar. This study enriches the roles of ERFs in SCW formation in poplar, which further provides references for revealing regulatory networks of TFs in xylem development in woody plants.