Fig. 4.

Gibberellic acid and abscisic acid modify microtubule organisation in dormant and non-dormant seeds. Microtubule organisation was assessed in embryos of dormant and non-dormant (4 days of stratification (DOS)) p35S::GFP-MBD seeds imbibed for 6, 24 and 48 h (HOI) in the presence of gibberellic acid (GA₃, 1 mM) (a–f) and abscisic acid (ABA, 10 μM) (g–l), respectively. Microtubule average orientation (indicated by purple lines inside the cells) was obtained using FibrilTool and is shown in the regions of interest (cells excluding anticlinal walls) that are delineated with yellow lines (a–c and g–i). d–f, j–l Microtubule organisation at the level of individual cells from dormant seeds imbibed for 6, 24 and 48 h with GA₃ and from non-dormant seeds imbibed for the same duration with ABA, respectively (scale bars, 10 μm in images of multicellular hypocotyl and 5 μm in images of individual cells). Values of anisotropy (m) and angles (n) of CMT arrays were calculated for the same samples. In (m, n) different letters indicated significant differences within the same column (one-way ANOVA), and asterisks indicate significant difference between non-dormant seeds and dormant seeds at every the same time point (t test, *P < 0.05, **P < 0.01). o Angle distribution (expressed in %) among cells of the various samples is shown for every sample. Changes in cell shape were evaluated by measuring the cell length and width (p) and area (q), in which different letters indicate significant differences among all samples of GA₃ or ABA treatments (one-way ANOVA), and stars indicate significant difference between non-dormant seeds and dormant seeds at every the same time point (t test, ^☆P < 0.05, ^☆☆P < 0.01). Values of CMT array angles (n) were expressed as means ± s.d. while values of CMT array anisotropy (m) and cell shape (p, q) were expressed as means ± s.e. Five biological replicates were analysed, and 30 cells from each replicate were used to calculate the indicated values