五种C4荒漠植物光合器官中含晶细胞的比较分析

COMPARATIVE STUDIES ON CRYSTAL IDIOBLASTS OF FIVE DESERT C_4 PLANTS

为了探讨荒漠植物适应干旱环境的机理,选择光合器官发生很大变化的5种C4荒漠植物进行了解剖结构的对比研究。结果表明,这5种植物中含晶细胞的数量、大小、形态和分布位置等存在差异。白梭梭(Haloxylon persicum)和梭梭(H.ammodendron)的同化枝普遍具有含晶细胞;沙拐枣(Calligonum mongolicum)的含晶细胞很少,一般只分布在贮水组织或靠近栅栏组织处;木本猪毛菜(Salsola arbuscula)的含晶细胞也不多,主要分布在栅栏组织和表皮细胞之间;猪毛菜(S.collina)的含晶细胞更少,仅在贮水组织中偶尔可见晶簇。比较梭梭、白梭梭和沙拐枣同化枝不同部位的解剖结构发现,梭梭同化枝基部含晶细胞最多,中部次之,顶部最少;白梭梭同化枝顶部的含晶细胞数量较多,中部及基部较少;沙拐枣同化枝顶部与基部的粘液细胞较多,中部较少,基部几乎没有栅栏组织,而其维管组织较为发达。综合晶体的酸碱溶解性及硝酸银组化分析结果,并参照能谱仪的分析结果得知,梭梭、白梭梭、沙拐枣和木本猪毛菜的叶片或同化枝中所含晶体的主要成分为草酸钙。通过比较解剖结构发现,梭梭和白梭梭的同化枝中含晶细胞最多,其它3种植物的同化器官中含晶细胞较少,而沙拐枣同化枝中有粘液细胞存在。

Aims Tissue cells that are specialized to produce crystals are referred to as crystal idioblasts. Crystal composition is predominantly calcium oxalate. Calcium oxalate crystal formation in plants appears to play a central role in a variety of important functions. Our aims are to study the occurrence, structures and functions of crystal idioblasts in Ca desert plants and assess the significance of crystal idioblasts in their drought resistance. Methods We selected five Ca desert plants whose photosynthetic organs are greatly deformed in appearance and structure. We investigated anatomical structures in desert plants Salsola collina and S. arbuscula and compared differences of assimilating shoots among Haloxylon ammodendron, H. persicum and Calligonum mongolicum using light microscopy. We identified crystals by using histochemical method and energy dispersive spectroscopy （EDS） and observed crystal microstructures under a scanning electron microscope. Important findings Crystal idioblasts exist in all five species, but there are differences in their distribution, position, amount, size and configuration. Haloxylon persicum and H. ammodendron have the most crystal idioblasts. Salsola arbuscula has fewer crystals existing between palisade tissues and epidermal cells. The fewest crystals exist in the water-storage tissue of S. collina. The crystals are in the water-storage tissue or near the palisade tissue in Calligonum mongolicum. The study of different parts Of assimilating shoots among H. ammodendron, H. persicum and C. mongolicum shows that in H. ammodendron the base has the most crystals, fewer in middle, least in top; in H. persicum the top of assimilating shoots has the most crystals, fewer in middle and base; there are more mucilage cells in top and base of C. mongolicum and fewer in middle; the base has few palisade tissue cells but developed vascular tissues. Histochemical and EDS results indicated that crystal nature of H. ammodendron, H. persicum, C. mongolicum and S. arbuscula is calcium oxalate. Among the five plants, H. persicum and H. ammodendron have the most crystal idioblasts, but there are mucilage cells in assimilating shoots of C. mongolicum.