CLE22Thr6 transgenic plants exhibited a short-root phenotype. A, Progeny of one CLE22Thr6 transgenic plant, showing different degrees of the short-root phenotype. Bar = 5 mm. B, A seedling of a CLE22Thr6 transgenic plant, showing termination of the primary root (arrowhead). Bar = 1 mm. C and D, Compared with the root meristems in Col-0 wild type (C), CLE22Thr6 transgenic plants (D) showed the aberrant root meristem (arrowhead). Bar = 50 μm. E and F, DR5::GUS expression in root meristems in Col-0 wild-type (E) and CLE22Thr6 transgenic (F) plants, showing the absence of GUS expression in the primary root meristem in the transgenic plant (arrowhead). Bar = 50 μm. Five-day-old seedlings were used for phenotypic observation and expression analyses.