青海高原不同海拔珠芽蓼叶绿体超微结构的比较

ULTRASTRUCTURE OF POLYGONUM VIVIPARUM L. GROWN AT DIFFERENT ELEVATIONS ON QINGHAI PLATEAU

用电子显微镜技术观察研究了生长于青海高原 3个海拔地带 (2 5 0 0 m、 32 0 0 m、 3980 m )的珠芽蓼(Polygonum viviparum L .)叶绿体的超微结构 ,发现随着海拔的升高 ,叶绿体结构呈现显著的变化趋势。 2 5 0 0 m和32 0 0 m处叶绿体形状规则 ,分布在细胞边缘。 3980 m处叶绿体膨大变形 ,且分布在整个细胞当中。海拔升高 ,类囊体膜减少 ,膜垛叠程度减小。不同海拔珠芽蓼叶绿体的类囊体膜结构差异较大 ,特点显著。随海拔升高 ,珠芽蓼叶绿体破坏程度增加。主要表现为类囊体膜肿胀、类囊体膜溶解和叶绿体破裂。许多破裂的叶绿体中残留有发达的基粒和大而多的淀粉粒。珠芽蓼叶绿体的这些结构特征 ,既是环境胁迫的结果 。

Variation in the ultrastructure of leaves of Polygonum viviparum L. grown at three different elevations (2500 m, 3200 m and 3980 m) was observed with the aid of an electron microscope. These observations revealed strong differences in chloroplasts ultrastructure between plants growing at different altitudes. A tendency was observed for chloroplasts to increasingly concentrate at the center of cells as elevation increases, presumably a form of protection from intensifying irradiation. The number of thylakoids per chloroplast and the degree of thylakoid stacking were both also observed to decrease with increasing elevation. This probably represents a strategy to reduce excess light absorption. Thylakoid swellings, a result of environmental stress, were observed in the chloroplasts of leaves from all three elevation levels. A positive association was observed between increasing elevation and observed levels of chloroplast deterioration. Appressed membranes in grana were observed in the residual thylakoid pieces in these damaged chloroplasts. It is suggested that chloroplasts with greater membrane stacking were more susceptible to damage from high irradiation.