Figure 1

STXM image processing steps. (A) The lignin map calculated as the average of several energy images near the lignin peak at 287.3 eV, minus the pre-edge at 280.9 eV. (B) Polysaccharides map calculated using the average of several energy images near the polysaccharide peak at 289.3 eV, minus the pre-edge at 280.9 eV. (C) Map of lignin divided by polysaccharides (image A divided by image B) with false colouring (warmer colours indicate more lignin in a given region). (D) Map showing clusters determined by PCA-cluster analysis where pixels with same colours have similar composition; pixel colours are not correlated to colours used in lignin and polysaccharide maps. (E) Spectrum extracted from the yellow (cell wall) pixels in panel D. (F) Spectrum extracted from the red (middle lamella) pixels in panel D.