Lucifer yellow and fluorescein isothiocyanate uptake by cells of Morinda citrifolia in suspension cultures is not confined to the endocytotic pathway

Abstract

ABSTRACT On the basis of previous reports that the uptake of Lucifer Yellow-CH (1YCH) is restricted to the endocytotic pathway in plant cells, it was anticipated that the probe would provide an estimate of endocytotic activity in suspension cultures of Morinda citrifolia. The uptake of LYCH and fluorescein isothiocyanate (FITC) have been examined in whole cell and protoplast forms of M. citrifolia. Rapid staining of the general cytoplasm and nucleus was observed with both fluorochrome treatments, while both markers were excluded from the central vacuole. In addition,treatment of cells with Probenecid, an anion transport inhibitor, prevented LYCH from entering cells. It is suggested that LYCH utilizes an anion transport mechanism to cross the plant cell plasma membrane. Furthermore, LYCH and FITC are excluded from the central vacuole due to the absence of such a mechanism on the tonoplast.