Cell walls from green (G2) or ripe (R) fruits were isolated according to Redgwell et al. (1992) (link), with some minor modifications. Briefly, 10–15 fruits were powered in liquid nitrogen and 20 g homogenized in 40 ml of PAW (phenol:acetic acid:water, 2:1:1, w:v:v). The homogenate was centrifuged at 4000 g for 15 min and the supernatant filtered through Miracloth (Merck, Bioscience, Nottingham, UK). The pellet was resuspended in 20 ml of water and the supernatant recovered as above. This step was performed twice. All supernatants were combined and dialysed (mol. wt cut-off 8000) against distilled water for 5 d at 4 °C. After dialysis, the PAW extract was centrifuged at 23 000 g for 20 min, and the supernatant was concentrated in a rotary evaporator to ∼5 ml, and finally freeze dried. This extract constitutes the PAW fraction. The residue from the first centrifugation, containing the cell wall material (CWM), was incubated overnight in 20 ml 90% DMSO to solubilize starch. The extract was then centrifuged at 4000 g, the pellet washed twice with 20 ml distilled water, and the CWM recovered after freeze drying. A minimum of three independent extractions per line and developmental stage were performed.