Fig. 5.

Changes in cell-wall structure are associated with changes in PME activities. (A) Total PME activity in 10-d-old roots of wild-type, pme17–1 and sbt3.5–1 KO mutants. Data represent the means ± SE of three independent experiments. Significant differences were determined with non-parametric Mann–Whitney test (*P < 0·05 and **P < 0·01). (B) Isoelectric focusing (IEF) of cell-wall-enriched protein extracts prepared from 10-d-old roots of wild-type, pme17–1 and sbt3.5–1 KO plants. The same PME activities (15 mU) were loaded for each condition. After IEF, PME activity was detected by incubation in a pectin (DM 85 %) solution, followed by staining with ruthenium red. Similar observations were obtained for three independent experiments. (C) Comparison between FT-IR spectra collected on wild-type and pme17 or sbt3.5 mutant plants. WS versus pme17–1 is represented as a black line. Col-0 versus sbt3.5–1 is represented as a red line. Horizontal lines refer to the P = 0·95 significance threshold (Student's test). Wavenumbers for which significant differences were observed are indicated in black for Ws versus pme17–1 and in red for Col-0 versus sbt3.5–1.