Study On The Main Chemical Constitutes Distribution Of Phyllostachys Edulis(Carr.) J. Houz Cell Wall

Bamboo, which possess many merits, such as wide varieties, wide distribution, fast growth, high strength, good toughness, can be sustainably used after planting, etc., is a renewable biological resource with the most development potential. Its unique multilayer structure and exquisite chemical constituents distribution is the key determinant of its excellent properties, and also is a basis issue that difficult to conquer. Delving into chemical constituents distribution within the unique multilayer structure is not only good for understanding the growth mechanism of bamboo from perspective of matter accumulation, developing bamboo plant genetic improvement and directive breeding, and also have important guiding significance for researching on biological energy conversion and developing biomimetic materials of imitation bamboo cell wall structure.Moso bamboo(Phyllostachys edulis(Carr.) J. Houz), a bamboo species with high economic value and use value in China, was chosen as the research object of this study, and the study was carried out closely around the theme of chemical constituents distribution. By using modern spectrum technology, the main chemical constituents distribution of moso bamboo cell wall was investigated from three different levels, namely multicellular level, double-cell level and single-cell level. Research was mainly focused on the distribution of main chemical constitutes within the multilayer structure, and semi-quantitative numerical of the main chemical constitutes concentration was obtained. A new technonlgy, namely Nano-IR, was firstly applied on the bamboo cell wall research, and the infrared spectroscopy of moso bamboo cell wall was firstly acquired at nano scale. Further understanding of the unique multilayer structure of moso bamboo cell wall will be achieved with the help of Nano-IR technology.The main results of this study are as follows:(1) The main chemical constitutes of cell wall between the outermost of a fiber sheath has obvious gradient distribution.(2) Lignin structural units have different distribution pattern within a fiber sheath, specifically, S lignin is relatively stable, G lignin shows a slight fluctuation change, and H lignin changes severely which indicate a very uneven distribution of H lignin. The distribution of hydroxy cinnamic acid is similar to H lignin. Cellulose has different distribution in different direction of a fiber sheath. In longitudinal direction, the cellulose concentration is higher in internal and lower in both ends, while tangential direction is just the opposite, its concentration is higher in both ends and lower in internal.(3) The main chemical constitutes of cell wall has different distribution at different radial position of moso bamboo culm. The cellulose concentration is under such law that middle part of bamboo culm wall > bamboo green side and bamboo yellow side. The cellulose concentration of bamboo green side and bamboo yellow side is almost equal which is about 0.88 times of that of the midlle part. The distribution law of hydroxy cinnamic acid and H lignin is bamboo yellow side > bamboo green side > middle part, and the ratio is 1.79:1.28:1 and 1.88:1.31:1 respectively. G lignin concentration is almost equal in bamboo green and middle part, and has highest value in bamboo yellow side. The distribution of total lignin and S lignin is not quite different in bamboo culm wall.(4) The main chemical constitutes of different bamboo cell types is different. Taking fiber cells as the reference, the ratio of main chemical constitutes concentration between fiber cell, parenchyma cell, primary xylem conduit cell and metaxylem catheter cell is: cellulose 1:0.42:0.51:0.43, H lignin 1:1.3:0.53:1.22, G lignin 1:0.95:0.58:1.14, hydroxy cinnamic acid 1:1.61:0.71:1.42 and total lignin 1:1.06:0.51:1.13, respectively.(5) Cellulose, S lignin, H lignin and hydroxy cinnamic acid has different distribution pattern between fiber cell wall, parenchyma cell wall and vascular cell wall. In fiber cells, the lowest concentration of cellulose and S lignin locates in middle lamella, but in parenchyma cells and vasculars cells, the lowest concentration of cellulose and S lignin do not in middle lamella, but in the secondary cell wall nearby cell lumen. For parenchyma cells and vasculars cells, hydroxy cinnamic acid and H lignin distributes in the whole cell wall, but for fiber cells, their concentration is really low or even has no distribution in some special region.(6) Both concentration and composition of main chemical constitutes make some difference in mutilayer structure of moso bamboo fiber indicated by Raman imaging. Cellulose evenly distribute in wide layers and has relative lower concentration in middle lamella and narrow layers; Lignin mainly distribute in the regions where there is relative fewer cellulose. The concentration of lignin is highest in middle lamella, and a step down distribution of lignin can be seen from peripheral to intracellular. A relatively high level of lignin concentration also exists in the layers around the cell cavity.(7) Band position of Nano-IR spectra is similar to that of traditional IR spectra indicated that Nano-IR technology can reflect the chemical information of moso bamboo cell wall correctly. Lignin and xylan has good synergy distribution in cell wall as shown in Nano-IR imagine indicated the intimate connection between lignin and xylan. At the nanoscale, the distribution of xylan and lignin in cell walls is not uniform, i.e. massive distribution on the transverse section and strip distribution on the tangential section.