TESTING TRANSGENIC GRAPEVINES FOR RESISTANCE TO PIERCES DISEASE

• Author(s): Kikkert, Julie; Reisch, Bruce; Walker, Andrew; Vidal, Jos?;
• Abstract: Numerous genes involved in plant disease defense have been isolated and when introduced and expressed in transgenic plants, fungal and bacterial diseases have been greatly reduced. This strategy is especially appropriate for grapevines, where the industry is rooted in traditional European grapes with strong name recognition and very high disease susceptibility. Our laboratory has developed a set of transformed grapevines harboring genes that produce anti-microbial peptides (AMPs). Seventy-six Chardonnay lines transformed with the magainin-type genes, mag-2 and MSI99, and with a PGL class gene, were produced. Some are now growing in tissue culture, in the greenhouse, and in the field (Vidal et al. 2003). AMPs are particularly effective against bacteria, and act by disrupting the cell membranes. The primary goal of this project is to study the potential resistance to Pierces disease (PD) of magainin and PGL-producing vines. In doing so, it becomes important to characterize the expression of these genes in each line. We are also studying whether AMPs can move from a transgenic rootstock to a non-transgenic scion. If so, it might be possible for engineered rootstocks to be used as a means to affect disease development in a range of scion varieties. Our data to date show that between 1 and 4 copies of the foreign gene can be found in each line studied, and that the inserted genes were correctly transcribed in 46 of 76 lines tested (via RT-PCR). An antibody was produced that can detect the presence of both mag-2 and MSI99 peptides. Using this antibody, AMP production was verified in leaf extracts of in vitro vines harboring mag-2 and MSI99 genes. Studies of PD resistance and movement of transgenic proteins from rootstocks to scions are at a very early stage in this newly funded project.
• Publication Date: Aug 2003
• Journal: 2003 Pierce's Disease Research Symposium