Transcription activator. Together with BRN1 and SMB, regulates cellular maturation of root cap. Promotes the expression of genes involved in secondary cell walls (SCW) biosynthesis. Expressed throughout the root cap, in both columella (COL) and lateral root cap (LRC) cells, with higher levels in the COL-adjoining LRC than the upper LRC. Also present at low levels expression in the tips of cotyledons and the cotyledon vasculature, as weel as in vasculature of the first pair of true leaves and at the hydathodes. Detectable in lateral root development when they reach 10 mm long. The NAC domain includes a DNA-binding domain and a dimerization domain.