ABSTRACT
Potted pepper plants were treated with Uncaria tomentosa bark extract applied to the soil @ 0.4 mg/ml or 1.6 mg/ml. The plants were grown under this condition for next 3 wk and then examined with electron microscopy methods to analyze the reaction of the first small leaf at the top of the pepper plant, then the one in the center of the plant and the lowest leaf at the bottom. During ontogenesis of control plants, black deposits in leaf vacuoles increased in number forming larger spheres. Nuclear chromatin gradually became slightly condensed. Chloroplasts contained more plastoglobuli but the number of starch grains decreased a little. Plastoglobuli in older leaves were extruded from chloroplasts. Large spherical deposits, dark droplets and opalescent crystal in the middle layer of mesophyll, which were visible in semithin preparations of control plants, disappeared after the treatment. Nuclei showed very strong condensation of chromatin. Chloroplasts showed degradation of grana and dilatation of thylakoids appearance as early as in youngest leaves. Plastoglobuli in plastids were enlarged. They were less homogenous and did not get expelled from the chloroplasts. Starch grains declined. Vesiculation of the ground cytoplasm was much stronger than in the control. Much more multivesicular bodies appeared, invigilating into the central vacuole. These observations suggested that Uncaria tomentosa extract enhanced natural ontogenesis until senescence of Capsicum leaf and additionally caused changes in cell structure and physiology.
