TB1 is a member of TCP transcription factor gene family. OsTB1 act as a negative regulator of tillering and potential target of SPL14. OsTB1 expressed in axillary buds and mutation in TB1 results in semidwarf phenotype with significant increase in tiller number.

TEOSINTE BRANCHED1 (OsTB1/TB1), a TCP family transcription factor, is a negative regulator of tillering (lateral branching). It works downstream of strigolactone signaling to inhibit bud outgrowth (Takeda et al., 2003; PMID: 12581309; Ishizaki et al., 2023; PMID: 36737003). OsTB1 is expressed in the axillary bud, as well as the basal part of the shoot apical meristem, vascular tissues in the pith, and the lamina joint. Transgenic rice plants overexpressing OsTB1 show reduced lateral branching. In addition, the rice cultivar carrying a classical morphological marker mutation, fine culm 1 (fc1), contains the loss-of-function mutation of OsTB1 and exhibits enhanced lateral branching ((Takeda et al., 2003; PMID: 12581309).