Abstract: The roots,stems and leaves of plants have their own physiological functions and morphological structures that adapt to the environment. In this study,Hordeum bogdanii (E+) with Epichloё endophytic fungi and H. bogdanii (E-) without endophytic fungi were used as experimental materials. After 21 day of treatment with 50 mmol·L^-1 and 100 mmol·L^-1 mixed alkali (Na₂CO₃∶NaHCO₃=1∶1),the anatomical changes of plant roots,stems and leaves were observed. The results showed that alkali stress led to root epidermis shrinkage and rupture,reduced the root vascular bundle area,increased the vessel diameter,epidermis,and endodermis thickness. And the degree of shrinkage of E+ plants was less than that of E-plants. Alkali treatment reduced the diameter of the air cavity of the E+ plant stem and increased the thickness of the epidermis. Alkali stress reduced the vascular bundle area and vessel diameter of leaves and increased the area of bulliform cells. And the vascular bundle area,vessel diameter and bulliform cell area of E+ were larger than those of E-plants under the same treatment conditions. By changing the microscopic structure of the roots,stems and leaves of the host plants,endophytic fungi promoted the absorption of water and inorganic salts,increased the protection of cells,reduced water loss and improved the gas exchange ability of the host plants under alkali stress.

Key words: Alkali stress, Endophytic fungi, Hordeum bogdanii, Microstructure

摘要： 植物的根、茎、叶具有各自的生理功能和适应环境的形态结构。本研究以带有Epichloё内生真菌的布顿大麦(Hordeum bogdanii)(E+)和不带内生真菌的布顿大麦(E-)为试验材料，用50 mmol·L^-1和100 mmol·L^-1的混合碱(Na₂CO₃∶NaHCO₃=1∶1)处理21 d后分别观察植物根、茎、叶显微结构的变化。结果表明：碱胁迫导致根的表皮出现皱缩和破裂，减小了根的维管束面积，增加了导管直径、表皮和内皮层厚度，并且E+的皱缩程度小于E-。碱处理使E+植株茎的气腔直径降低，表皮厚度升高。碱胁迫减小了叶的维管束面积和导管直径，增大了泡状细胞面积，且E+的维管束面积、导管直径和泡状细胞面积大于相同处理条件下的E-植株。内生真菌通过改变宿主植物根、茎和叶的显微结构，促进宿主植物在碱胁迫中加快对水分和无机盐的吸收、增加对细胞的保护和减少水分的散失以及提高植物的气体交换能力。

关键词: 碱胁迫, 内生真菌, 布顿大麦, 显微结构