Fang Jiang-yu, Wan Xiao-chun
Postdoctoral Research Station in Horticulture, Anhui Agricultural University, Hefei 230036, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2008 Sep;28(9):2196-200.
XPS was applied to analyze the surface chemical composition and structure of the tea plant leaf and root. It was detected that the surface is made up of mainly 4 elements: C, O, N and Al, with little P and F in abaxial leaf. Based on the botanic epidermis structure and the chemical composition, with the help of the standard spectrum data bank on line and the wood XPS study results, and through line Gaussian and Lorentizian the mixed, the binding energy of C(1s) of the leaf surface was classified as 3 types: the first was C1, with the electron binding energy of 285 eV, from C-C or C-H group, representing lipid compound like cutin and wax. C2 with the binding energy of 286.35 eV in the adaxial and 286.61 eV in the abaxial, came from the single bond of carbon and oxygen C-O, mainly standing for cellulose. C3 with the binding energy of approximately 288 eV (288.04 eV in adaxial and 288.09 eV in abaxial) was the sign of C=O group, which is acyl in protein with the confirmation of N(1s) (399-401 eV)and O(1s) analyses. In the root surface, besides the same compounds of cutin and wax (C1, binding energy 285 eV), cellulose (C2, binding energy 286.49 eV) and protein (C3, binding energy 288.78 eV)as in the leaf, there appeared C5 type with the binding energy of 283.32 eV. Because it was lower than C1, it was estimated as carbon linking to metal. Both the leaf and the root surfaces didn't have C4, a type of O-C=O, which is common in wood surface with the highest oxidated carbon of 289-289.5 eV binding energy, indicating that organic acid secreted by the root existed freely on the root surface, without any chemical association with the surface compounds. The results of the separated spectrum of O(1s) supported the above C(1s) results. By the ratio of each type of C, there were more oxygen groups in the abaxial than in the adaxial, implicating more active chemical properties on the abaxial. Compared with the leaf, cutin and wax was little in the root and oxygen groups were many, verifying more active chemical property on the root surface and more water and solute molecules passing. Again the protein content was in the order of root, abaxial and adaxial, indicating the same order of the wetness degree. Higher binding energy of Al than 73. 50 eV showed oxidized aluminum in tea plant surface, which might enhance the absorption, and more oxidized aluminum in the root meants that it has more powerful absorbability.
采用X射线光电子能谱（XPS）分析茶树叶片和根部的表面化学成分及结构。检测发现，表面主要由碳（C）、氧（O）、氮（N）和铝（Al）4种元素组成，叶背含少量磷（P）和氟（F）。依据植物表皮结构和化学成分，借助在线标准光谱数据库及木材XPS研究结果，通过高斯和洛伦兹混合线形拟合，将叶片表面C(1s)的结合能分为3种类型：第一种为C1，电子结合能为285 eV，来自C-C或C-H基团，代表角质和蜡质等脂质化合物。C2在叶正面的结合能为286.35 eV，在叶背为286.61 eV，来自碳与氧的单键C-O，主要代表纤维素。C3的结合能约为288 eV（叶正面为288.04 eV，叶背为288.09 eV），是C=O基团的特征峰，经N(1s)（399 - 401 eV）和O(1s)分析确认为蛋白质中的酰基。在根部表面，除了与叶片中相同的角质和蜡质化合物（C1，结合能285 eV）、纤维素（C2，结合能286.49 eV）和蛋白质（C3，结合能288.78 eV）外，还出现了结合能为283.32 eV的C5类型。因其低于C1，推测为与金属相连的碳。叶片和根部表面均未出现C4类型，即O-C=O，这在木材表面常见，其最高氧化态碳的结合能为289 - 289.5 eV，表明根部分泌的有机酸在根表面自由存在，未与表面化合物发生任何化学结合。O(1s)的分谱结果支持上述C(1s)的结果。通过各类C的比例可知，叶背的含氧基团比叶面多，意味着叶背的化学性质更活跃。与叶片相比，根部的角质和蜡质较少，含氧基团较多，证实根表面的化学性质更活跃，有更多水分和溶质分子通过。蛋白质含量同样呈根、叶背、叶面的顺序，表明湿度顺序相同。Al的结合能高于73.50 eV表明茶树表面存在氧化铝，这可能增强吸收能力，根部更多的氧化铝意味着其吸收能力更强。
