Abstract:

In order to understand the dynamics of storage reserves in chili pepper fruits during ripening，pericarps of green and red fruits were examined by means of histochemistry and transmission electron microscopy. As fruits fully expanded and remained green，the endocarp and the parenchyma of the mesocarp contained a large number of starch grains，while the epicarp and the collenchymas of the mesocarp lacked storage reserves. As fruits ripened to red，starch grains disappeared，a large number of plastidial lipid droplets accumulated in the epicarp，and both plastidial and cytosolic lipid droplets accumulated in great numbers in other tissues. Cytosolic lipid droplets were elliptical and were located in the cytoplasm，whereas the plastidial lipid droplets were spherical or rod-like and located within chromoplasts that occurred in all tissues. Spherical plastidial lipid droplets tended to be present in the epicarp，whereas rod-like lipid droplets tended to be present in other tissues. Both cytosolic and plastidial lipid dropletsstrongly reacted with osmium tetroxide to produce orange color，indicating the presence of double bonds. In summary，the storage reserves in green pericarp were starch grains that were exclusively present in the parenchyma of the mesocarp and endocarp，and the storage reserves were converted to cytosolic and plastidial lipid droplets as the fruits ripened to red. Plastidial lipid droplets accumulated in all tissues，while cytosolic lipid droplets were absent in the epicarp. All lipid droplets contained unsaturated oil.

Key words: Capsicum annuum, fruit, storage reserve, lipid droplet, starch grain