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About the Authors:
Ai Oikawa
Affiliations Feedstocks Division, Joint BioEnergy Institute, Emeryville, California, United States of America, Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
Hiren J. Joshi
Affiliations Feedstocks Division, Joint BioEnergy Institute, Emeryville, California, United States of America, Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
Emilie A. Rennie
Affiliations Feedstocks Division, Joint BioEnergy Institute, Emeryville, California, United States of America, Department of Plant & Microbial Biology, University of California, Berkeley, California, United States of America
Berit Ebert
Affiliations Feedstocks Division, Joint BioEnergy Institute, Emeryville, California, United States of America, Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
Chithra Manisseri
Affiliations Feedstocks Division, Joint BioEnergy Institute, Emeryville, California, United States of America, Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
Joshua L. Heazlewood
Affiliations Feedstocks Division, Joint BioEnergy Institute, Emeryville, California, United States of America, Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
Henrik Vibe Scheller
* E-mail: [email protected]
Affiliations Feedstocks Division, Joint BioEnergy Institute, Emeryville, California, United States of America, Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America, Department of Plant & Microbial Biology, University of California, Berkeley, California, United States of America
Introduction
Plant cell walls are complex structures, predominantly composed of polysaccharides. Secondary walls develop in some cell types after the termination of cell expansion, and these walls usually contain lignin in addition to polysaccharides. The polysaccharides in secondary walls are largely represented by cellulose and hemicelluloses, particularly xylans. Pectin and other hemicelluloses, e.g. mannans and xyloglucans are much less abundant in secondary walls. For a recent review of hemicellulose structure and function, see Scheller and Ulvskov [1]. Xylans have a backbone of 1,4-linked β-xylosyl residues, some of which are substituted with single glucuronosyl (GlcA), 4-O-methyl-GlcA, and arabinofuranosyl residues. Furthermore, the xylose residues can be acetylated at O-2 and/or O-3, and in Poales the arabinofuranosyl residues can be feruloylated at O-5. More complex side chains can also be present, and the structural patterns vary both between species and tissues. Secondary walls in angiosperms contain xylan as the major hemicellulose, and this xylan generally has little or no arabinose and a...