Lybeer Bieke, Koch Gerald, VAN Acker Joris, Goetghebeur Paul
Ghent University, Laboratory of Biology, Research Group Spermatophytes, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium.
Ann Bot. 2006 Apr;97(4):529-39. doi: 10.1093/aob/mcl016. Epub 2006 Feb 7.
Bamboos are among the most important plants in the world. The anatomical structure and mechanical properties of the culm internode are well documented. Fewer details are available of the culm node. The aim of this study was a topochemical investigation on lignification and cell wall thickening in developing and maturing bamboo nodes. The deposition sequence and distribution of lignin structural units and cell wall thickening in different anatomical regions of the node of Phyllostachys viridiglaucescens and Phyllostachys nigra are discussed.
Cell wall thickening and lignification are investigated in the outer part of the nodal region and in the diaphragm of developing and maturing P. nigra culms and in maturing culms of P. viridiglaucescens of different age classes. The lignification during ageing was studied topochemically by means of cellular UV microspectrophotometry. A combination of light microscopy and image analysis techniques were used to measure cell wall thickness.
The fibre and parenchyma cell wall thickness does not significantly increase during ageing. In the diaphragm, the cell walls are thinner and the cell diameter is larger than in the outer part of the node. In shoots, the lignin content in the epidermis, hypodermis and in both fibre and parenchyma cells of the diaphragm is relatively low compared with older culms. The fibre and parenchyma cells of the diaphragm have higher values of p-coumaric and ferulic acids than fibre and parenchyma cells of the outer part of the node.
It was hypothesized that the combination of more hydroxycinnamic acids and of thinner cell walls in combination with higher cell diameters (lower density and lower stiffness) in the diaphragm than in the outer part of the node may play an important role in the biomechanical function of the node by acting as a spring-like joint to support the culm by bending forces.
竹子是世界上最重要的植物之一。竹茎节间的解剖结构和力学性能已有充分记载。关于竹节的细节则较少。本研究的目的是对发育中和成熟竹节中的木质化和细胞壁增厚进行组织化学研究。讨论了淡竹和紫竹节不同解剖区域中木质素结构单元的沉积顺序和分布以及细胞壁增厚情况。
研究了发育中和成熟的紫竹竹茎节区域外部以及隔膜中的细胞壁增厚和木质化情况，以及不同年龄级别的成熟淡竹茎节中的情况。通过细胞紫外显微分光光度法对老化过程中的木质化进行了组织化学研究。结合光学显微镜和图像分析技术来测量细胞壁厚度。
在老化过程中，纤维和薄壁组织细胞壁厚度没有显著增加。在隔膜中，细胞壁比节的外部更薄，细胞直径更大。在竹笋中，与老竹茎相比，表皮、皮下组织以及隔膜中的纤维和薄壁组织细胞中的木质素含量相对较低。隔膜中的纤维和薄壁组织细胞比节外部的纤维和薄壁组织细胞具有更高的对香豆酸和阿魏酸含量。
据推测，隔膜中比节外部含有更多的羟基肉桂酸、更薄的细胞壁以及更大的细胞直径（更低的密度和更低的硬度），这些因素共同作用，可能通过充当类似弹簧的关节来承受弯曲力以支撑竹茎，从而在节的生物力学功能中发挥重要作用。
