Fig. 4.

CEP3 peptide accelerates entry into mitotic quiescence under C limitation and inhibits Glc-dependent recovery into S-phase. (A) Time course showing the effect of C limitation of S-phase cell number. Plants were grown with restricted light (≤50 µmol m^–2 s^–1) to prevent photoautotrophic growth. Treated WT plants were continually exposed to the CEP3 peptide from imbibition. The red box indicates the age of plants used in (B). (B) Number of EdU-positive cells after 24 h of incubation with Glc. dpg=days post-germination. (C) After 5 d of C-limited growth, WT plants were treated with Glc (1 mM) or Glc (1 mM) plus CEP3 peptide. CEP3 treatment reduces the number of root meristem cells re-entering S-phase of the cell cycle within 12 h after Glc addition. Plants were grown in suboptimal light to day 5 to synchronize meristematic cells into mitotic quiescence. Glc (1 mM) or CEP3 (1 µM)+Glc was added at time 0 after synchronization and plants were assayed at the specified times. n≥5 for each time point in (A–C). Plants in (A–C) were grown in standard 1/2 MS medium. Lower case letters in (A) and (B) indicate statistically significant differences within each time point (P<0.05, ANOVA with Bonferroni correction for multiple comparison; Genstat). In (C), **P<0.01; ***P<0.001 (t-test, compared with no CEP treatment at the same time point).