Fig. 3: Callose synthesis provokes an increase in cell wall hygroscopicity and porosity through its deposition in cell wall spaces.

a, Water vapour isotherms and Park model representation of inducible L11 following estradiol vs a mock (DMSO) control after 14 weeks of growth. b, DSC thermoporosimetry histogram showing the distribution of pore diameter in association with the ratio of freezing water (in percentage) using the inducible (Ind.) and WT backgrounds in different conditions (DMSO mock and estradiol-inducing condition) following 14 weeks of growth. The higher the percentage is, the higher a range of pore diameters is represented in the considered lignocellulosic biomass. Individual data points represent biological replicates in DMSO (WT DMSO n = 7, Ind. DMSO n = 10) or estradiol conditions (WT estradiol n = 7, Ind. estradiol n = 10). For inducible lines, results of two independent lines were pooled in each bar. Statistical analysis was done using one-way ANOVA (P = 2 × 10⁻¹⁶) followed by Tukey’s multiple comparisons test. Significance values for P < 0.05 were grouped and are displayed as letter groups above bar plots. c, Representative cellulose deposition in a longitudinal view of a poplar fibre cell revealed by Direct Red staining (magenta) from inducible lines following estradiol-induced callose synthesis during 14 weeks. d, Same as c but merged with callose immunolocalization to reveal the integration pattern of the ectopic polymer. e, Close-up of d. Arrowheads indicate spots of callose deposition in cellulose gaps. Two independent lines (n = 3) were used for this experiment. Scale bars, 5 µm.