Expression of peat moss VASCULAR RELATED NAC-DOMAIN homologs in Nicotiana benthamiana leaf cells induces ectopic secondary wall formation

Plant Mol Biol. 2021 Jun;106(3):309-317. doi: 10.1007/s11103-021-01148-6. Epub 2021 Apr 21.


The homologs of VASCULAR RELATED NAC-DOMAIN in the peat moss Sphagnum palustre were identified and these transcriptional activity as the VNS family was conserved. In angiosperms, xylem vessel element differentiation is governed by the master regulators VASCULAR RELATED NAC-DOMAIN6 (VND6) and VND7, encoding plant-specific NAC transcription factors. Although vessel elements have not been found in bryophytes, differentiation of the water-conducting hydroid cells in the moss Physcomitrella patens is regulated by VND homologs termed VND-NST-SOMBRERO (VNS) genes. VNS genes are conserved in the land plant lineage, but their functions have not been elucidated outside of angiosperms and P. patens. The peat moss Sphagnum palustre, of class Sphagnopsida in the phylum Bryophyta, does not have hydroids and instead uses hyaline cells with thickened, helical-patterned cell walls and pores to store water in the leaves. Here, we performed whole-transcriptome analysis and de novo assembly using next generation sequencing in S. palustre, obtaining sequences for 68,305 genes. Among them, we identified seven VNS-like genes, SpVNS1-A, SpVNS1-B, SpVNS2-A, SpVNS2-B, SpVNS3-A, SpVNS3-B, and SpVNS4-A. Transient expression of these VNS-like genes, with the exception of SpVNS2-A, in Nicotiana benthamiana leaf cells resulted in ectopic thickening of secondary walls. This result suggests that the transcriptional activity observed in other VNS family members is functionally conserved in the VNS homologs of S. palustre.

Keywords: Hyaline cell; Peat moss; Sphagnum palustre; VND; VNS; Water storage; Water-conducting.

MeSH terms

  • Cell Wall / genetics
  • Cell Wall / metabolism
  • Gene Expression Profiling
  • Gene Expression Regulation, Plant / genetics*
  • High-Throughput Nucleotide Sequencing
  • Plant Leaves / metabolism*
  • Plant Proteins / genetics
  • Plant Proteins / metabolism
  • Plants, Genetically Modified / genetics
  • Protein Domains
  • Sphagnopsida / genetics*
  • Tobacco / metabolism*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Xylem / metabolism


  • Plant Proteins
  • Transcription Factors