中国特有种大理白前对高寒环境的形态适应特征

Morphological Adaptation to Alpine Environment of a Chinese Endemic Species,Cynanchum forrestii

高寒草甸具有辐射强、低气压、风大、昼夜温度骤变等不利于植物生长的环境特征,为了探讨中国特有种大理白前(Cynanchum forrestii)对高寒环境的生态适应,以川西南九龙县高寒草甸(海拔3 100~3 500 m)的大理白前为对象,采用光学显微镜技术和扫描电镜技术研究了大理白前的形态解剖特征,并采用TCC法分析了花粉和种子的生活力。结果表明:大理白前的叶、茎、花均被有丰富的单列细胞组成的表皮毛;叶片和茎的表皮角质层较厚;叶的气孔较大而下生,栅栏组织和海绵组织发达;茎表皮细胞小、细胞壁厚,皮层由7层细胞组成,排列紧密,细胞内储藏有丰富的物质,维管柱所占比例较大,木射线数量较多,髓部发达且储藏物质丰富;根维管组织发达,皮层细胞储藏有丰富的物质;种子和花粉活力较高、合生花冠、合蕊柱、种子具有种毛,以及种皮厚而坚硬等特征为提高繁殖效率提供了保障。上述结果表明,大理白前具有一整套适应高寒环境的外部形态和内部结构特征,使其保持较高的抗辐射、抗旱和抗寒能力,为大理白前在高寒环境中成功生存和繁衍奠定了结构基础。

Alpine meadows exhibited environmental characteristics such as intense radiation,low air pressure,strong winds and sudden changes in diurnal temperature,which were unfavorable for plant growth.In order to explore the ecological adaptability of Cynanchum forrestii,an endemic species of China to the alpine meadow environment(altitudes of 3 100-3 500 m) in Jiulong County,southwest Sichuan Province,the anatomical features of various organs of C.forrestii were examined by optical microscopy and scanning electron microscopy,and the pollen and seed viability were analyzed by the TCC method.The results showed that the leaves,stems and flowers of C.forrestii were covered with epidermis composed of rich single-row cells;the cuticle of leaf and stems epidermis was thick;the stomata were large and located on the lower surface of the leaves,palisade tissue and sponge tissue were developed;the stem epidermal cells were small and the cell wall was thick,and the cortex was composed of seven layers of cells,which were closely arranged,there were rich substances stored in the stem cells,and the vascular columns accounted for a large proportion of stem,the pith was developed and rich in stored substances;the root vascular tissue was well-developed,rich storage substances in cortical cells;the characteristics of high seed and pollen vitality,combined corolla,combined pistil column,the seed had seed hair,and thick and hard seed coat provide guaranteed for improving reproductive efficiency.The above results indicated that C.forrestii possessed a comprehensive array of external and internal structural characteristics,which enabled adaption to high-altitude cold environments while maintaining elevated levels of radiation resistance,drought resistance,and cold tolerance,and laid a structural foundation for the successful survival and reproduction of C.forrestii in the alpine environment.