六种芦荟叶的解剖结构及其与芦荟素含量的相关性

应用半薄切片法、高效液相色谱法(HPLC)和荧光显微镜研究了6种芦荟叶的结构、芦荟素的含量和储藏芦荟素的组织。结果表明，6种芦荟叶均由表皮、光合组织、储水组织和维管束组成，都表现出明显的旱生植物肉质叶的结构特征，表皮由一层扁平的细胞组成，其外壁加厚，并覆盖着厚的角质膜，气孔器凹陷，储水组织发达。6种芦荟叶的结构存在显著差异。木立芦荟(Aloe arborescens Mill．)和易变芦荟(A．mutabilis Pillans)的光合组织细胞呈长柱状，类似栅栏薄壁组织。中华芦荟(A．vera L.var．chinensis Berg．)、库拉索芦荟(A．vera L．)、皂叶芦荟(A．saponaria Hawer)和绿芦荟(A．greenii Bak．)则为等直径薄壁细胞。木立芦荟、中华芦荟、易变芦荟和库拉索芦荟的维管束中有大型薄壁细胞，皂叶芦荟和绿芦荟的维管束中无大型薄壁细胞。木立芦荟、易变芦荟和库拉索芦荟在光合组织和储水组织之间有一层不含叶绿体的小型薄壁细胞，包围着储水薄壁组织，称之为储水组织鞘。中华芦荟、皂叶芦荟和绿芦荟则没有储水组织鞘。HPLC测量结果表明，木立芦荟叶芦荟素含量最高，库拉索芦荟和易变芦荟次之，中华芦荟、皂叶芦荟和绿芦荟含量最低。荧光显微镜观察结果表明，在紫外光和蓝光下，黄色和黄绿色小球体仅存在于维管束的大型薄壁细胞、维管束鞘和储水组织鞘中，而光合组织和储水组织中没有黄色和黄绿色小球体。因此，维管束中大型薄壁细胞、维管束鞘和储水组织鞘是芦荟素等蒽醌类物质的储藏场所。综上所述，芦荟素含量与维管束的大型薄壁细胞、维管束鞘和储水组织鞘的情况密切相关。

Relationship Between Leaf Structure and Aloin Content in Six Species of Aloe L.

The leaf structure, content and the storage location of aloin in the leaves of six species of Aloe L. were studied by means of semi_thin section, high performance liquid chromatography (HPLC) and fluorescent microscope. Results showed that all leaves consisted of epidermis, chlorenchyma, aquiferous tissue and vascular bundles. The leaves had the xeromorphic characteristics, including thickened epidermal cell wall, thickened cuticle, sunken stomata and well_developed aquiferous tissue. With the exception of this, there were remarkable differences in leaf structure among the six species. The chlorenchyma cells were similar to palisade tissues in Aloe arborescens Mill. and A. mutabilis Pillans, but isodiametric in A. vera L., A. vera L. var. chinensis Berg., A. saponaria Hawer and A. greenii Bak. A. arborescens , A. mutabilis , A. vera and A. vera var. chinensis included large parenchymatous cells at the vascular bundles, whereas no such cells were observed at the vascular bundles of A. saponaria and A. greenii . In A. arborescens , A. mutabilis and A. vera , the aquiferous tissue sheaths were present and composed of a layer of small parenchymatous cells without chloroplasts around the aquiferous tissue. While there were no aquiferous tissue sheaths in A. vera var. chinensis , A. saponaria and A. greenii . The HPLC revealed that the content of aloin was high in A. arborescens , low in A. vera , and very low in A. saponaria among the six species. The fluorescent microscopy showed that the yellow_green globule only appeared in the large parenchymatous cells of vascular bundles, vascular bundle sheath and aquiferous tissue sheath, but not in the chlorenchyma and aquiferous tissue. Consequently, the large parenchymatous cells of vascular bundles, vascular bundle sheath and aquiferous tissue sheath were the storage location of aloin. They were positively correlated with the content of aloin.