Synthesis of Polysaccharides in Phragmoplasts Isolated from Tobacco BY-2 Cells

Autoradiographic experiments using preparations of isolatedphragmoplast obtained from tobacco cultured cells revealed thatthe radioactivity incorporated into insoluble material fromUDP-³H]glucose was exclusively present at the cell plate ofisolated phragmoplasts. Most of the radioactivity incorporatedinto isolated phragmoplasts from UDP-¹⁴C]glucose was solubilizedby 1,3-ß-glucanase and the solubilized radioactivitywas associated only with glucose, indicating that most of theradioactivity was incorporated into 1,3-ß-glucan.In the presence of high concentrations of unlabeled UDP-glucose,isolated phragmoplasts incorporated radioactivity from UDP-³H]xylose.Most of the radioactivity incorporated into insoluble materialwas present at several sites distributed around the nuclei,while only little was found at the cell plate. (Received October 2, 1991; Accepted February 24, 1992)