Expression of Anti-microbial Genes in Transgenic Grapevines for enhanced disease resistance

Grapevines are susceptible to numerous diseases harming both plants and profits. Transgenic grapevines that resist disease would provide better disease control as well as economic benefits from the reduction in spray applications. Our overall goal has been to research and develop methods to create transgenic selections of elite cultivars with improved resistance to diseases. Vines of Chardonnay expressing an endochitinase gene have improved resistance to Botrytis bunch rot. Data from 2002 were convincing, but data collected in 2003 and 2004, while providing some evidence for Botrytis resistance, were less convincing. The timing of inoculation may affect the results obtained. Chardonnay vines expressing genes for antimicrobial peptide production show enhanced resistance to crown gall disease and some possible improvements in powdery mildew resistance. Evidence is beginning to confirm that the crown gall resistance is related, as expected, to peptide levels. Tests are underway to confirm the relative effects of various peptides on two fungal pathogens of grapevine (Botrytis and powdery mildew). The results of these tests will lead to new transformation experiments with genes chosen to be most active against these diseases.