烤烟衰老过程中叶片超微结构及生理特性变化研究

为观察烤烟叶片衰老过程中叶肉细胞超微结构的变化规律，分析其衰老过程中细胞超微结构与生理特性变化的特征，探讨结构与生理过程的相关变化规律，应用透射电子显微镜结合生理指标分析，发现叶片衰老过程中细胞主要发生以下变化：（1）叶绿体基粒整齐片层结构的丧失是细胞进入衰老期后最早和最明显的现象，线粒体和细胞核保持功能至衰老后期，质膜是最后发生裂解的细胞器；（2）线粒体超微结构变化主要集中在嵴数的变化上，成熟后期，线粒体嵴数明显减少，大部分内膜已经破裂，内部可供呼吸作用的面积减少，呼吸强度降低；（3）生理指标分析表明，叶绿素是受叶片衰老影响最显著的指标，叶绿体片层结构的破坏引发了整个细胞衰老。

Study on Ultrastructure and Physiological Characteristic Changes of Senescence Flue-cured Tobacco Leaves

The research studied the cell structure and metabolite changes of flue-cured tobacco leaves during the aging process, based on the observation of ultrastructure of tobacco leaves using transmission electron microscope and the analysis of physiological and biochemical characteristics. The results indicated that： （1）The loss of the ordered grana lamella in chloroplast appeared firstly and most obviously, the mitochondria and nuclear could keep their functions until late senescence stage. The plasma membrane was the last decomposed organdie. The full development of starch grain contributed to the irregular chloroplast. （2）Involving the definite changes of mitochondria ultrastructure, the amount of cristae was observed to decrease evidently, and the inner membrane was broken, while the area and intension of respiration reduced in the over-maturity stage. （3）The physiological analysis showed that chlorophyl was evidently affected by leaf senescence, and the destruction of chloroplast grana lamella could result in the complete cell senescence.