[Effect of doubled CO2 and O3 concentration and their interactions on ultrastructure of soybean chloroplast]

The effect of doubled CO2 and O3 concentration on the ultrastructure of chloroplast in leaf cells of soybean was tested by open-top chamber method, and examined under transmission electron microscope. The results showed that under doubled CO2 concentration, the amount and volume of starch grains in chloroplast increased, but the chloroplast membrane and the lamellar structure still kept integrated. The accumulation of starch grains was restrained, and the chloroplast membrane and the lamellar structure were disorganized under doubled-O3 concentration. The ultrastructure of chloroplast was destroyed in different degrees under the interaction of doubled CO2 and O3 concentration. The damage to chloroplast arose from the abrupt doubling of CO2 and O3 was more severe than that from gradual increase of CO2 and O3 concentration. The negative effect of O3 was partly compensated by the positive effect of doubled CO2.