Polysaccharide compositions of leaf cell walls of forage chicory (Cichorium intybus L.)

The polysaccharide compositions of cell walls isolated from the laminae and midribs of chicory (cv. Grasslands Puna II) leaves were investigated. The walls, which, except for the walls of xylem tracheary elements in vascular bundles, were non-lignified, were fractionated progressively with 50 mM CDTA, 50 mM Na2CO3, 1 M KOH, 4 M KOH, 4 M KOH + 3.5% H3BO3, and hot water. Monosaccharide and linkage analyses of the polysaccharides in the walls and wall fractions indicated that the polysaccharides were similar to those in the non-lignified walls of other dicotyledons. However, the proportions of pectic polysaccharides were particularly high (67% of the total wall polysaccharides in the laminae). These included homogalacturonans (50% of the total wall polysaccharides in the laminae) and rhamnogalacturonan-I (RG-I). In contrast, the proportions of cellulose, xyloglucans, heteroxylans and glucomannans were particularly low. The xyloglucans were probably fucogalactoxyloglucans. The wall polysaccharides from the leaf laminae differed from those from the midribs in having higher proportions of homogalacturonans, lower proportions of non-pectic polysaccharides, and RG-I with a higher ratio of galactan to arabinan.