毛竹材导管分子的纹孔特征

【目的】探究毛竹材导管细胞壁上纹孔结构的主要特征,为深入认识竹类植物生理输导作用和竹材横向渗透机制提供理论依据。【方法】通过观测毛竹(Phyllostachys edulis(Carr.)J.Houz.)材导管及导管树脂铸型的扫描电镜图像,研究纹孔的几何形态、分布规律和纹孔膜结构等特征。【结果】依据纹孔缘与纹孔口的相对位置和大小关系,将毛竹导管具缘纹孔分为两侧均没有纹孔缘(PⅠ)、仅在单侧有纹孔缘(PⅡ)和两侧都有纹孔缘(PⅢ)3种类型。纹孔内口和外口(短轴方向)尺寸分别为0.9～2.7 μm和1.1～3.8 μm; 纹孔膜有微纤丝暴露与被覆盖两种状态,多数具渗透性; 后生木质部导管上的纹孔呈选择性分布,总是密集于靠近维管束几何中心的一侧管壁; 毛竹维管束内分散有小导管,且相互以具缘纹孔对连接; 部分导管内含有侵填体。【结论】综合运用常规解剖方法和树脂铸型技术,不仅可以较系统地研究导管主要特征,还发现了毛竹材中特殊的导管结构和纹孔分布规律。

Characteristics of pits in the vessel element of moso bamboo (Phyllostachys edulis(Carr.) J.Houz.)

Objective] Exploring the main characteristics of pits in the cell wall of vessel elements could provide a basis for deeper understanding of physiological conductance and transverse permeability in bamboo. Method] The geometry and distribution of pits and pit membrane characteristics were observed through images of vessels in moso bamboo (Phyl-lostachys edulis (Carr.)J. Houz.) and their resin casts. Result]According to the relationship between relative position and size of the borders and apertures, three types of bordered pit, namely PⅠ, PⅡ and PⅢ, were categorized. The si-zes of the inner and outer pit apertures along the short axis were approximately 0.9-2.7 μm and 1.1-3.8 μm, respective-ly. Most of the pit membranes were open. Moreover, pits in metaxylem vessels showed selective distribution, i.e. always concentrating in the side towards the center of the vascular bundle. Smaller vessel members were found connecting each other with bordered pits within the vascular bundle. Additionally, tyloses were found in some vessels. Conclusion]The main characteristics of vessels could be acquired systematically by combining resin casting with common anatomy meth-ods. In addition, the distribution regularity of pits and special structures of vessels, which are normally difficult to re-cord, could be explored through this method.