Invertase in Cell Walls of Plant Tissue Cultures

Abstract

In 1955 Ball (1) published a report in which he demonstrated that the growth of various tissue cultures upon media containing certain oligosaccharides resulted in the appearance of the hydrolysis products of these sugars in the medium. Ball speculated that the appearance of these hydrolysis products was due to the uptake of the oligosaccharide, hydrolysis within the tissue cells, and a subsequent release of the smaller molecules into the medium. Epp (8) reinvestigated certain aspects of this problem tutilizing tissue cultures derived from Cupressus funebris and a larger number of oligosaccharides. His findings were in general agreement with those of Ball. However, Epp obtained some preliminary evidence to indicate that the appearance in the medium of the hydrolysis products of some of the complex sugars was not necessarily the result of the mechanism proposed by Ball. Instead he hypothesized that the hydrolysis may be the result of carbohydrase activity either on the cell surface or in the medium itself because of the release of these enzymes by the tissue. Burstr6m (4, 5, 6) demonstrated that excised roots hydrolyze sucrose in liquid media. Street and Lowe (20) indicated that excised tomato roots take up the glucose moiety of sucrose by a phosphorylating reaction at the cell surface which results in the splitting of sucrose, an uptake of glucose probably as a phosphate ester, and a retention of fructose in the medium. Myrback and Willstaedt (13), among others, have shown that invertase is bound to the cell wall in yeast, most probably outside the plasma membrane. Putman and Hassid (16) produced evidence which strongly indicates that invertase is localized in the cell walls or interstices of the cell walls of leaves of Canna indica. More recently, Kivilaan, et al. (9) reported on the presence of several enzymes including invertase in cell wall preparations of corn coleoptiles. In the present report, evidence is produced to show the widespread occurrence of invertase in cell wall fractions of plant tissue cultures. Materials & Methods