The Distribution and Orientation of Cell Wall Components of Moso Bamboo Parenchyma

Ground parenchyma tissue is regarded as the basic structural units, and its functions are storage. In the present work, Confocal fluorescence microscopy was used to visualize the morphology of separated parenchyma. Moreover, TEM image displayed the concentric layering structure of secondary parenchyma wall and the thickness of the sub-layer ranges from 0.2 similar to 0.3 mu m. Based on the above findings, the top chemistry of lignin and cellulose in parenchyma was studied by 532 nm in situ confocal Raman spectroscopy. The cell wall morphology of parenchyma was observed by integration the band regions from 2 789 similar to 3 000 cm(-1). Due to the limitation of spatial resolution, the secondary wall cannot be divided into sub-layers. Raman imaging obtained from 380 and 1 600 cm(-1) show that the cellulose within the secondary wall of parenchyma was uniform distribution, but the lignin mainly accumulated within the compound middle lamella and its aromaticringconjugated coniferaldehyde and sinapaldehyde displayed the same distribution pattern. Moreover, the distribution pattern of hydrocinnamic acids, which are attached to lignin and hemicelluloses via ester and ether bonds, was also heterogeneous. The ratio of Raman band intensity revealed that the cellulose molecular chain within the parenchyma and narrow layer of fiber wall was more parallel to the cell axis compared to the broad layer of fiber. The above results will deepen our understanding of ultrastructure, cell wall topochemistry and molecular orientation of bamboo parenchyma. It will provide theoretical instruction for the highly efficient and precise utilization of bamboo resources in the further.