Probable transcription activator that regulates root development by controlling cell proliferation in root meristem. May mediate responses to auxin in the root. May act as promoter of the flowering transition through up-regulation of SOC, FT and LFY. Preferentially expressed in roots (PubMed:7549482). In root meristem, expressed in external cells of columella, lateral root cap and atrichoblasts. In mature root, expressed in the central cylinder (PubMed:11855641). Expressed in leaf vasculature, young floral meristems and nectaries (PubMed:18203871). During embryo development, expressed in a punctate pattern from the globular stage to the torpedo stage. By auxin in root phloem. Retarded root growth, and altered root meristem size and stem-cell patterning. Late flowering phenotype. XAANTAL is the Mayan word for 'go slower' in recognition of the retarded root growth phenotypes of xaantal mutants.