Effects of Menazon and Usnic Acid on Histochemical and Ultrastructural Changes During Germination of Mung Beans1

Abstract

Abstract Menazon (S-(4,6 diamino-s-triazin-2-methyl) o,o-dimethyl phosphorodithioate) an organophosphate insecticide, and usnic acid, an allergen present in lichens, inhibited germination of mung bean (Phaseolus mungo L.). On the third day of germination, cotyledons were examined histochemically and ultrastructurally and the resultant photomicrographs showed abundant starch grains and protein bodies in the treated seeds compared to the controls. Electron microscopic examination showed extensive endoplasmic reticulum and ribosomes along with vacuoles and normal mitochondria in control tissue. In contrast, the presence of protein bodies and disruption of the cytoplasmic organization were conspicuous in the menazon- and usnic acid-treated mung beans. This suggests impaired utilization of food reserves during germination.