中文摘要：

为了解景天植物的抗寒机理，以露天栽培越冬的苔景天、胭脂红景天、联合勘察加景天为材料，采用光学显微与电子显微技术分析景天植物叶片结构特征变化与抗寒性的关系. 结果表明：3种景天植物叶肉细胞间隙大，通气组织发达，维管束周围以及表皮细胞内分布粘液细胞. 低温胁迫后抗寒性强的苔景天类囊体的结构受到影响较小，叶绿体形状没有发生明显的变化；胭脂红景天叶绿体受到低温伤害，部分叶绿体变形；抗寒性弱的联合勘察加景天叶绿体受到严重伤害，由原来的纺锤形变为圆球形，类囊体已经解体或正在解体. 在低温胁迫后3种景天的淀粉粒减少，粘液细胞数量增多且颜色加深，叶表皮细胞外覆盖蜡质增多，苔景天的蜡质层最厚，而联合勘察加景天蜡质最少，苔景天叶肉细胞液泡中囊泡数量增多. 因此，在低温胁迫下苔景天叶绿体表现出较高的稳定性，叶肉细胞液泡中囊泡较多，叶表皮细胞外覆盖较厚的蜡质层，可能是其具有较强抗寒性的原因. 图3 参16

英文摘要：

In order to understand the structure adaptation mechanism of Sedum plant to cold stress, we investigated with light microscope and electronic microscope the leaf structures of wintering Sedum acre, S. spurium cv. coccineum, and S. kamtschaticum subsp. ellacombianum planted in outdoor field of Beijing region. The results showed that there were visible intercellular space and well developed aerenchyma in mesophyll. A lot of mucilage cells were found in the epiderm and around the vascular tissue. The low temperature from autumn （Oct. 12） to winter （Dec. 1）, did not influence the thylakoid structure of S. acre, or obviously injured its chloroplasts, while the structure of some chloroplasts in the leaves of the other two Sedum plants was damaged. Especially in the leaves of S. kamtschaticum subsp. ellacombianum, the shape of chloroplast changed from fusiform to spheriform, and the thylakoid were disintegrated. Low temperature also led to decreased starch grains, increased mucilage cells with darkened color, and thickened waxiness layer on the epiderm in all the three sedum plants. The S. acre showed much thicker waxiness layer and more vesicles in vacuole of mesophyll cells than the other two sedum plants. The results suggested that the stronger resistance to cold stress of S. acre may result from its higher stability of chloroplast structure, larger increasing vesicles in vacuole of mesophyll cells, and visibly thicker waxiness layer on the epiderm. Fig 3, Ref 16