Fig. 4

Proline effects on meristem size are independent from GA, IAA and cytokinin. a Root meristem sizes, measured at 7 dag as number or cortex cells spanning from the QC to the TZ, of wild types (dark grey bars) and p5cs1 p5cs2/P5CS2 (light grey bars), upon pharmacological treatment with either 20 μM GA3, 0.1 nM IAA, or 10 μM kinetin. Error bars indicate Standard Error (SE). All pairwise comparisons (Student’s t test) showed that proline mutants treated with either GA3- or IAA, had root meristems highly significantly larger than untreated mutants (p < 0.001 +++), and highly significantly smaller than treated wild types (p < 0.001***). Kinetin-treated proline mutants, however, had root meristems highly significantly smaller than either treated mutants (p < 0.001***) , but only significantly smaller than untreated wild types (p < 0.01 ++). b Root meristem sizes, at 7 dag, of genetic combinations (light grey bars) mimicking either GA3 treatment (p5cs1 p5cs2/P5CS2, gai-t6, rga-24), or kinetin treatment (either p5cs1 p5cs2/P5CS2, arr1 and p5cs1 p5cs2/P5CS2, arr12), compared to parental lines (dark grey bars). c qRT-PCR analysis shows no statistically significant differences in the expression levels of ARR1, ARR12, GAI and RGA between p5cs1 p5cs2/P5CS2 (light grey) and wild-type controls (dark grey). ACTIN 8 was used as a reference gene to normalize the qRT-PCRs