Cellulose and 1,3-glucan synthesis during the early stages of wall regeneration in soybean protoplasts

Protoplasts isolated from cultured soybean cells (Glycine max (L.) Merr., cv. Mandarin) were used to study polysaccharide biosynthesis during the initial stages of cell wall-regeneration. Within minutes after the protoplasts were transferred to a wall-regeneration medium containing [¹⁴C]glucose, radioactivity was detected in a product which was chemically characterized as cellulose. The onset and accumulation of radioactivity into cellulose coincided with the appearance fibrils on the surface of protoplasts, as seen under the electron microscope. At these early stages, a variety of polysaccharide-containing polymers other than cellulose were also synthesized. Under conditions where the protoplasts were competent to synthesize cellulose from glucose, uridine diphosphate-[¹⁴C]glucose and guanosine diphosphate-[¹⁴C]glucose did not serve as effective substrates for cellulose synthesis. However, substantial amounts of label from uridine diphosphate glucose were incorporated into 1,3-glucan.Abbreviations ECM extracellular material - GLC gas liquid chromatography - GDP-glucose guanosine diphosphate glucose - UDP-glucose uridine diphosphate glucose - U enzyme units as defined by Sigma Chemical Corp., St. Louis, Mo., USA