An enzymic method for measuring the molecular weight exclusion limit of plasmodesmata of bundle sheath cells of C4 plants

Abstract

Bundle sheath cell strands have been prepared from four C4 plant species and used to study the molecular weight exclusion limit of plasmodesmata located in the cell wall of bundle sheath cells. By measuring the activity and the inhibition of enzymes located within the bundle sheath cells of the strands in the absence or presence of a variety of inhibitors of different molecular weight, the molecular weight exclusion limit of the plasmodesmata located within the cell walls of bundle sheath cells has been determined. Using a variety of Reactive dyes (of different molecular weight) which inhibit a number of cytosohc enzymes, as well as a graded series of Reactive Yellow 2 derivatives as probes, it has been shown that compounds with molecular weights greater than about 900 daltons do not pass through the plasmodesmata of bundle sheath cells of C4 plants.