Transcription activator. Together with SMB and BRN2, regulates cellular maturation of root cap. Promotes the expression of genes involved in secondary cell walls (SCW) biosynthesis. Expressed in the root cap, in both columella (COL) and COL-adjoining lateral root cap (LRC) cells. 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 1 mm long. The NAC domain includes a DNA-binding domain and a dimerization domain.