Changes in Typical Organelles in Developing Cotyledons of Soybean

Soybean cotyledonary cells harvested every 5-10 days at 15 to 60 days after flowering (OAF), were investigated by means of light and transmission electron microscopy. In the early developing stages (15-20 OAF) most of the cells were occupied by large, centrally located vacuoles while the cytoplasm was restricted to a thin layer against the cell wall and contained numerous ribosomes, mitochondria, plastids, small amounts of endoplasmic reticulum (ER) and minute lipid bodies. At about 25 OAF, spherical organelles which contained protein, lipid and sugar (PLS bodies), appeared and then increased in number and in size. Vacuoles had protein deposits lining the inner surfaces of the tonoplasts. At 30-35 OAF, the PLS bodies lost their characteristic ciccular shape because of invaginations containing cytoplasmic materials and small vacuoles . Such transformed PLS bodies, fragmented vacuoles and protein bodies became d ifficult to distinguish from eac h other. At this stage, the cytoplasm contained abundant rough ER with cisternae, dictyosomes , lipid bodies and plastids . At 35-40 OAF, protein bodies which vari ed in size and shape were observed in ce lls a long with lipid bodies and rough ER. At about 40 OAF the plastids reached maximum size and number and then most disappeared . In the final stage ( 55-60 OAF) , protein bodies became homogeneous in electron density with completion of protein accumulation. Initial paper received April 16 1984 Manuscript received June 22 1985 Direct inquiries to K. Saio Telephone number: 81-2975-6-8051