Invertase in Cell Walls of Plant Tissue Cultures

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Abstract
Cell wall fractions of tissue cultures derived from Rosa stem, Pyrus floral tube, staminate cones of Cupressus and Libocedrus, Ephedra stem, 3 strains of tobacco stem, and 3 strains of maize endosperm were tested for invertase activity. All tissues but 1 tobacco tissue exhibited varying degrees of invertase activity. The highest activity was exhibited by Ephedra cell walls and the lowest by one of the the tobacco tissues. The cytoplasmic fractions of 10 of the tissues were also tested. Four of them showed no activity while the other 6 exhibited rather low activities. Partial release of the enzyme was obtained by inoculation of 1 week under toluene. Papain was not particularly effective in solubilizing the invertase, instead it proved to be somewhat deleterious. Sensitivity to uranyl ions and insensitivity to Ca and ethylenediamine tetracetic acid, and ability to hydrolyze raffinose to melibiose and fructose were used as additional criteria to establish that the sucrose hydrolyzing capacity of the cell walls of these tissue cultures was in fact due to invertase and not merely to a surface phenomenon involving bound hydrogen ions. It is suggested that the presence of invertase in these tissue cultures is purely fortuitous and probably serves no function.