Fig. 2.

TK VI-induced inhibition of cell proliferation and cell elongation in the Col-0 root tip. (A) Time course of TK VI-induced reductions in root meristem size in Col-0 seedlings at 5 DAG. Data shown are averages with the SD (n=20). (B) Root meristems of 5 DAG Col-0 seedlings transplanted to medium without (MS) or with 5 μM TK VI for 12h. The meristem is marked with a vertical black line. The boundary between the meristem zone and the elongation zone is marked with a black arrowhead. The black box is an enlarged image of the boundary between the meristem zone and the elongation zone. (C) Cortical cell length in the differentiation zone of 5 DAG Col-0 seedlings grown on medium without (Control) or with 5 μM TK VI. Data shown are averages with the SD (n=20). The asterisks denote Student’s t-test significance compared with untreated plants: ***P<0.001.

(D) Differentiation zones of seedlings mentioned in (C). The white arrowheads indicate the length of a single cortical cell. (E) TK VI-induced reduction in CYCB1;1 _pro :GFP expression in Col-0. Six-day-old seedlings were transferred to medium without (MS) or with 5 μM TK VI for 3h before GFP fluorescence was monitored. (F) The effect of TK VI on the expression of cell cycle-related genes in the Col-0 root tip. Six-day-old Col-0 seedlings were transplanted to medium without (Control) or with 5 μM TK VI for 3h, and the 2mm root tips were harvested for RNA extraction and qRT–PCR analysis. The transcript levels of the indicated genes in Col-0 without TK VI treatment were arbitrarily set to 1. The error bars represent the SD of triplicate reactions. The asterisks denote Student’s t-test significance compared with untreated plants: ***P<0.001. Scale bars=50 μm (B, D, E).