Probable transcription factor that acts as positivie regulator of brassinosteroid (BR) signaling (PubMed:19220793, PubMed:22685166). Functions downstream of BRI1 and GSK2 to modulate BR responses. Acts as a direct target of GSK2 kinase to mediate BR responses (PubMed:22685166). Involved in feedback inhibition of BR biosynthetic genes. Repressed by BZR1 (PubMed:19220793). Cooperatively functions in a transactivating complex with SMOS1 to enhance the transcription of the SMOS1 target PHI-1, and regulate plant organ size (PubMed:28069545). Interaction between SMOS1 and DLT is a crosstalk point for auxin and brassinosteroid signaling (PubMed:28069545). Interacts with GSK2 (PubMed:22685166). Interacts with SMOS1 (via C-terminus) (PubMed:28069545). Expressed in the shoot apical meristem (SAM) and elongating cells of young seedlings. Expressed in leaf joints, culms, internodes, stems, young panicles, primary roots and lateral roots. Down-regulated by 24-epibrassinolide. Phosphorylated on serine and threonine residues by GSK2. Dephosphorylated during response to brassinosteroid. Semi-dwarf phenotype with small and wide leaves. Erect leaf and panicle phenotype. Reduced lamina joint bending angles. Reduced tiller number and seed set. Reduced brassinosteroid sensitivity and altered expression of brassinosteroid-responsive genes (PubMed:19220793, PubMed:28069545). Decreased cell size, increased cell number, and abnormal cell arrangement and microtubule orientation (PubMed:28069545). Belongs to the GRAS family.