Identification and characterization of a wood-associated NAC domain transcription factor PtoVNS11 from Populus tomentosa Carr.

Abstract

Here, we isolated a NAC transcription factor PtoVNS11 from Populus tomentosa Carr. Molecular characterization showed that PtoVNS11 was involved in the regulation of secondary cell wall formation in poplar. NAC domain transcription factors are important regulators that activate the secondary wall biosynthesis in wood formation. In this study, we isolated a NAC domain transcription factor PtoVNS11 from Populus tomentosa Carr. PtoVNS11 shares high identity with SND1 of Arabidopsis thaliana (59.6 %) and PtrWND1B (97.9 %) of P. trichocarpa. Gene expression analyses showed that PtoVNS11 gene was mainly accumulated in xylem and stem of poplar. Further, GUS expression driven by the PtoVNS11 promoter was observed in vascular tissues of vegetative and reproductive organs in transgenic Arabidopsis. Promoter deletion analysis revealed that the fragment (-283 to -171) with the secondary wall NAC-binding element was required for tissue-specific expression of the PtoVNS11 gene. Subcellular localization analysis showed that PtoVNS11:GFP fusion protein was localized in the nucleus. Transgenic poplar plants carrying 35S:PtoVNS11 exhibited dwarf phenotypes with shorter internode as compared to wild-type plants. PtoVNS11 overexpression resulted in massive deposition of lignin and increased thickening of secondary walls in transgenic poplar. Transcription analysis showed that the expression levels of many wood-associated genes were up-regulated in transgenic plants overexpressing PtoVNS11. Taken together, our results indicate that PtoVNS11 may be involved in the regulation of the secondary wall biosynthesis during wood formation in poplar.