Abstract: Soybean (Glycine max (L.) Merr. ) cotyledons of 40 days after flowering were labeled and traced with aH-leucine, and examined by the technique of electron microscopic autoradiography (EMARG). The results showed that the transport pathway of 3H-leucine in cotyledon cells is cell gap-cell wall-cytoplasm. After the aH-leucine went into cytoplasm, it was distributed more into endoplasmic reticulam, plastids, vacuoles and edge of protein bodies near cell wall. As the tracing time extended, most of the silver grains went into vacuoles and developing protein bodies. Few silver grains were found in Golgi bodies. The analysis by liquid scintillation of the aH-leucine in isolated protein subunits showed that the radiostrength was increased as the labeling and tracing time extended. The possible transport pathway of storage protein in cotyledon cell was discussed according to the above results.

Key words: Soybean cotyledon, Storage protein, Electron microscopic autoradiography, Transport pathway