Transcription activator that binds to the secondary wall NAC binding element (SNBE), 5'-(T/A)NN(C/T)(T/C/G)TNNNNNNNA(A/C)GN(A/C/T)(A/T)-3', in the promoter of target genes (By similarity). Involved in xylem formation by promoting the expression of secondary wall-associated transcription factors and of genes involved in secondary wall biosynthesis and programmed cell death, genes driven by the secondary wall NAC binding element (SNBE). Triggers thickening of secondary walls (PubMed:16103214, PubMed:25148240). Interacts with NAC083/VNI2. Expressed in root, shoot and hypocotyl vascular elements, columella root caps, epidermal and cortex root cells and root-hypocotyl junctions. Observed predominantly in root imature xylem vessels (PubMed:18445131). Present in root developing xylems (PubMed:16103214, PubMed:17565617). Specifically expressed in vessels in the secondary xylem of the root-hypocotyl region, and in vessels but not in interfascicular fibers in stems (PubMed:25148240). Up-regulated during xylem vessel element formation. Expressed preferentially in procambial cells adjacent to root meristem. The NAC domain includes a DNA binding domain and a dimerization domain. Embryo deffective. Belongs to the plant vascular related NAC-domain protein family.