Xyloglucan deposition

Since the total contour length of a xyloglucan molecule is 40 to 400 times greater than the diameter of a microfibril (8), it would seem inevitable that most of the newly deposited xyloglucan chains will have the opportunity to bind to the several microfibrils across which they are randomly laid down (Fig. 2b) (25). 

All other polymers are synthesised inside the cell and transported in lipid vesicles that fuse with the plasma membrane and release their contents into the extracellular space. It is likely that this process occurs alongside cellulose deposition, and hence wall assembly is likely to be influenced by the interaction between cellulose and non-cellulosic polymers. After initial deposition, cell walls can be further modified both by integration of further secreted polymers and by the action of modifying enzymes such as pectin methyl esterase, xyloglucan endo-transglycosylase and peroxidase. 

Glucomannans occur as reserve materials in certain seeds such as bluebell (Endymion non-scriptus) while the mucilages of other species are or contain polyuronides. Xyloglucans (with galactose side chains) are found as amyloids in seeds of tamarind Tamarindus) [65], Annona [43] and several other species. These polysaccharides again are deposited in the endosperm cell walls. 

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