AtRaptor1B -/- plants show altered shoot architecture. (A) B- plant at flowering. The primary shoot apex, center, has ceased growth and is surpassed by axillary branches. Compare to Col, A- in 3C. (B) Col, A- and B- primary shoot length. (C) Mature B- plant, showing a bushy phenotype due to decreased primary shoot growth and increased branching. (D) Shoot apex of the plant in C, magnified 4.5×. Axillary branches outgrow the primary shoot, which arrests in a whorl of sterile flowers. (E) Col, A- and B- cauline and rosette branch number. (F) Col, A- and B- cauline and rosette branch length. B- primary shoots are smaller than Col or A-, and secondary shoots initiate more frequently than Col or A- but are not significantly longer than Col or A-.