内蒙古两种生态型羊草叶绿体色素含量以及形态特征的对比

Comparative study on chloroplast pigment concentration and morphology between two ecotypes of Leymus chinensis in Inner Mongolia

羊草(Leymus chinensis)是在内蒙古草原上广泛分布的一种优良牧草,根据叶片颜色可以分为灰绿羊草和黄绿羊草。在逆境胁迫下,灰绿羊草较黄绿羊草具有更高的光合能力和更强的环境适应性,但是其机理还不清楚。本研究选取内蒙古呼和塔拉草原的灰绿羊草和黄绿羊草,测定其叶片叶绿素和类胡萝卜素的含量,分析两种生态型羊草叶片叶绿体数目、大小和形态结构特征,以及叶绿体光合蛋白复合体的差异。结果表明,灰绿羊草叶片叶绿素和类胡萝卜素含量均极显著高于黄绿羊草(P<0.01);单个细胞中叶绿体数目黄绿羊草极显著高于(P<0.01)灰绿羊草,但是叶绿体体积以及单个叶绿体中基粒类囊体的数目灰绿羊草极显著大于黄绿羊草(P<0.01);此外,黄绿羊草叶片不同细胞中含有两种形态结构不同的叶绿体;BN-PAGE(蓝绿温和胶)的结果显示,灰绿羊草叶绿体光系统Ⅰ(PSⅠ)和光系统Ⅱ(PSⅡ)二聚体的含量高于黄绿羊草。所以,较高的叶绿素、类胡萝卜素以及PSⅠ和PSⅡ蛋白复合体含量是灰绿羊草高效光合作用和更强环境适应能力的重要基础。

Leymus chinensis is a high-quality forage widely distributed in grasslands of Inner Mongolia.It can be classified as either the gray-green type or the yellow-green type according to its leaf color.Previous studies have shown that the graygreen grass has a higher photosynthetic capability and stronger environmental adaptability than the yellow-green type under stressful conditions.However,the mechanism underlying this difference is still unclear.Gray-green and yellow-green grass of the Huhetala grassland in Inner Mongolia were sampled in this study.The concentrations of chlorophyll and carotenoids in the leaves of the two L.chinensis ecotypes were quantitatively determined by a spectrophotometer.The number,size,and morphology of chloroplasts were characterized by transmission electron microscopy.The photosynthetic protein complexes of the gray-green and yellow-green grass were separated via blue native gel electrophoresis(BN-PAGE).The results indicated that the gray-green type had higher concentrations of chlorophyll and carotenoids in its leaves compared with the yellow-green type.Even though there were more chloroplasts per cell in the yellow-green leaves,chloroplasts were larger with a higher number of grana thylakoid in the gray-green leaves.In addition,two kinds of chloroplasts with different morphologies were allocated into different cells in the yellow-green leaves.A higher level of photosystemⅡ(PSⅡ)dimers and photosystemⅠ(PSⅠ)complexes were detected in the gray-green type through BN-PAGE.It can,therefore,be inferred that the higher concentrations of chlorophyll,carotenoids,and PSⅠand PSⅡprotein complexes are an important basis for more efficient photosynthesis and stronger environmental adaptability of the gray-green grass ecotype.