EVALUATION OF SIGNAL SEQUENCES FOR THE DELIVERY OF TRANSGENE PRODUCTS INTO THE XYLEM

• Author(s): Dandekar, Abhaya; Aguero, Cecilia; Gilchrist, David; Guimar?es, Rejane; Labavitch, John;
• Abstract: Xylella fastidiosa (Xf), a gram-negative bacterium, is the causative agent of Pierces disease in grapevines. Because Xf is xylem-limited, it will be essential that any anti-Xylella gene product be present in the xylem in an effective concentration. Work on understanding the mechanism of how proteins are targeted to this plant compartment will be relevant for the delivery of therapeutic proteins into the xylem. In addition, it will be a useful tool for Xylella and glassy-wing sharpshooter (GWSS) gene function studies. We collected xylem exudate from grapevines and analyzed its protein composition by two-dimensional gel electrophoresis. Peptide spectrum and Blast analysis showed that the proteins found in the exudates are secreted proteins that share function similarities with proteins found in xylem exudates of other species. The corresponding cDNA sequences of 5 of them were found in the TIGR Vitis vinifera gene index. The signal sequences of xylem proteins Chi1b and similar to NtPRp27 were fused to the mature pear polygalacturonase inhibiting protein (pPGIP)-encoding gene. The expression of these chimeric genes will be evaluated in transient and permanent transformations in order to evaluate their ability to target pPGIP to the xylem. The results of this research will not only be applied in projects that test anti-Xylella gene products that should be delivered into the xylem but also in functional studies that are intended to target the products of Xf and GWSS genes to the xylem.
• Publication Date: Dec 2005
• Journal: 2005 Pierce's Disease Research Symposium