Abstract:

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 losing 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.