TESTING TRANSGENIC GRAPEVINES FOR RESISTANCE TO PIERCES DISEASE

• Author(s): Kikkert, Julie; Reisch, Bruce; Rosenfield, Claire-Lise; Walker, Andrew;
• Abstract: Magainins are small antimicrobial peptides (AMPs) that inhibit growth of numerous bacteria and fungi. Some AMP-transgenic lines of Chardonnay have improved resistance to tumorigenic strains of crown gall (Agrobacterium vitis). Other researchers have claimed that similar AMPs induce grapevine resistance to Pierces disease (PD). Sixteen Chardonnay lines transformed with the magainin-type AMP genes, mag-2 and MSI99, and with a PGL class gene, were produced and tested for PD resistance using a greenhouse needle inoculation technique. Most lines were susceptible, but several showed reductions in symptom development and reductions in plant tissue bacterial counts. These vines are being propagated for a field trial to test for resistance under conditions of natural inoculation. Tests are also underway to quantify the level of peptide production in each transgenic line. In addition, in vitro assays are being conducted to evaluate the relative effect of these and other peptides on growth of Xylella fastidiosa (Xf). MSI99 and ESF39 inhibit Xylella growth more effectively than do the other peptides tested, according to results obtained to date.
• Publication Date: Dec 2005
• Journal: 2005 Pierce's Disease Research Symposium