Abstract
Internalization of fluorescently labeled CPPs, __p__VEC, transportan and scrambled __p__VEC, in a range of plant cells was investigated. Cellular uptake of the peptides was found to be tissue dependent. __p__VEC and transportan were distinctly internalized in triticale mesophyll protoplasts, onion epidermal cells, leaf bases and root tips of seven‐day old triticale seedlings but showed negligible florescence in coleoptile and leaf tips as observed under a fluorescence microscope. Further, __p__VEC and transportan uptake studies were focused on mesophyll protoplasts as a system of investigation. In fluorimetric studies transportan showed 2.3 times higher cellular internalization than __p__VEC in protoplasts, whereas scrambled __p__VEC failed to show any significant fluorescence. Effect of various factors on cellular internalization of __p__VEC and transportan in protoplasts was also investigated. The cellular uptake of both the peptides was concentration dependent and nonsaturable. The cellular uptake of __p__VEC and transportan was enhanced at low temperature (4 °C). The presence of endocytic/macropinocytosis inhibitors did not reduce the cellular uptake of the peptides, suggesting direct cell penetration, receptor‐independent internalization of __p__VEC and transportan into the plant cells. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.