We investigated leaf tissue structure, leaf epidermis characteristics and chloroplast ultrastructure of Polygonum viviparum at different altitudes (2300, 3200 and 3900 m) on the Qilian Mountain, using paraffin section, scanning electron microscopy and transmission electron microscopy methods. The results showed that plant leaves were typical bifacial. With increasing altitude, the number of leaf epidermal hair reduced but the diameter of hair increased, with more compact of the cuticular wax layer on leaf lower epidermis. Leaf thickness reached a maximum at 3200 m and was increased by 39.6% and 50.5%, respectively, compared with that from 2300 m and 3900 m. From 2300 m to 3200 m, the cell layers of palisade tissue increased from two to three, while intercellular space decreased. The cell layer of spongy tissue did not change, whereas intercellular space increased with increasing altitude. At 3900 m, the number of cell layer of palisade tissue reduced to two, epidermal cell volume and the intercellular space of palisade tissue increased while the intercellular space of spongy tissue decreased. The thickness of epidermal cell increased. There was no significant difference among three altitudes in the number of cell layers. The accumulation of surface appurtenances and the substomatal appendages, and stomata density of lower epidermis increased with altitude. Meanwhile, the position of stomata changed from arched epidermis to invagination. From 2300 m to 3200 m, the grana lamella increased from 6-9 to 8-12 and then reduced to 2-3 at 3900 m. The number of grana decreased, the lamellae became dense, the arrangement direction of grana was irregular at 3900 m. The chloroplasts swelling and the envelope partially degradation could be observed. The correlations among the anatomical characteristics of leaves indicated an apparent co-evolution between parts of anatomical indices in the leaves. In particular, indices such as spongy tissue thickness exhibited high plasticity across altitudes. Our results suggested that diffe-rences in anatomical structure and ultrastructure characteristics of P. viviparum along altitude were adaptation strategies for the complicated alpine heterogeneous habitats.
采用石蜡制片、扫描电镜和透射电镜方法,研究了祁连山植被垂直分布带海拔2300、3200和3900 m 珠芽蓼叶片组织结构、叶表皮特征和叶绿体超微结构对海拔升高的适应性变化。结果表明: 珠芽蓼为异面叶,随海拔升高,叶片表皮毛数目减少而直径增大变粗,表皮蜡质层结构更加致密。叶片厚度在海拔3200 m最大,分别比海拔2300和3900 m增加了39.6%和50.5%。从海拔2300到3200 m,栅栏组织细胞层数由2层增加为3层且细胞排列紧密,海绵组织细胞间隙逐渐增大;在海拔3900 m处,栅栏组织细胞层数减少至2层且细胞间隙增加,海绵组织细胞间隙减小,表皮细胞厚度增加,但细胞层数在3个海拔间无显著差异。随海拔升高,叶下表皮附属物和气孔下室物质的积累增加,气孔密度增加,张度降低,气孔位置由表皮拱起变为内陷。从海拔2300到3200 m,基粒片层由6～9层增至8～12层;至海拔3900 m,基粒片层降为 2～3层且片层之间变得致密,基粒数目减少且排列方向不规则,叶绿体膨大,被膜部分降解。随海拔升高,叶片部分解剖结构指标之间呈现出明显的协同进化,表现出较大的可塑性。珠芽蓼叶片解剖与超微结构在不同海拔表现出的差异显示,表型可塑性及其对高山异质环境和海拔变化的适应特征,是植物长期适应高山复杂环境的结果。.
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