Transcriptional activator (PubMed:19717544, PubMed:22974309). Involved in lateral root formation. Regulated by the transcriptional activators ARF7 and ARF19 (PubMed:17259263). Functions in the initiation and emergence of lateral roots, in conjunction with LBD18, downstream of ARF7 and ARF19 (PubMed:19717544, PubMed:23749813). Acts downstream of the auxin influx carriers AUX1 and LAX1 in the regulation of lateral root initiation and development (PubMed:26059335). Homodimer and heterodimer with LBD18. Expressed in roots and faintly in shoots. During lateral root formation, expressed in the lateral root primordia, and the developing, emerged, and mature lateral roots. By auxin. Reduced number of lateral roots. Belongs to the LOB domain-containing protein family.