Cell wall composition of Camellia oleifera Abel. shell: new insights into its composition distribution and ultrastructure

Abstract Camellia oleifera Abel. shell (COS) is an agricultural waste in quantities exceeding a million tons annually. The ultrastructure of the COS cell wall and the distribution of lignocellulose components were investigated. The microscopic results showed that COS contains two types of cells, sclerenchyma cells (SC) and parenchyma cells (PC). SC contained 50.4 % hemicellulose, 17.6 % cellulose and 30.9 % lignin while PC contained 35.2 % hemicellulose, 23.7 % cellulose and 35.0 % lignin. The distribution of lignocellulose components in COS is non-homogeneous. Lignin is alternately distributed with polysaccharides in the PC wall. In SC, hemicellulose is mainly present in the secondary wall S2, while lignin was mainly found in the compound middle lamella, and cellulose mainly exists in the secondary wall, S3. A comprehensive model of the cell wall ultrastructure and lignocellulose distribution of COS was given. This study provides a fundamental understanding of COS cell walls and can aid in the future graded utilization of COS.