[21] Isolation of amyloplasts from suspension cultures of soybean

This chapter discusses a method for the isolation of amyloplasts from suspension cultures of soybean. The amyloplasts is nonphotosynthetic plastids in which starch accumulation is the dominant activity. As starch is widespread in nonphotosynthetic cells and is made only in plastids, it follows that amyloplasts are widely distributed. However, the most obviously developed amyloplasts are found in the major starch storing tissues, such as the endosperm of cereals and the tubers of potatoes. Amyloplasts vary in size according to their stage of development and to the plant species. Amyloplasts are bounded by an envelope that consists of two membranes, but compared to chloroplasts, the internal membrane systems are poorly developed. The method for amyloplast isolation involves sucrose density gradient centrifugation of lysates of protoplasts made from suspension cultures of soybean cells. The age of the suspension cultures used to make amyloplasts has a critical effect on the yield of amyloplasts.