Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2007
Publication Date: N/A
Technical Abstract: Ontogenic resistance has been shown to confer near-immunity to powdery mildew (Uncinula necator) in grapevine. Studies have shown OR to be effective and temporally similar, in all previously studied genotypes of Vitis. To characterize the basis of OR, a diverse collection of 79 genotypes of Vitis was screened for OR using a diverse population of powdery mildew. The screen resulted in the classification of 23 genotypes as having a statistically significant gain of resistance, and a single genotype was shown to be susceptible past veraison. This is the first example of a grapevine with persistently susceptible berries. With genetic variation for OR identified, several studies into factors contributing to OR have followed, including metabolic profiling and electron microscopic study of the berry cuticle and a comparative proteomics screen of berry peels. The cuticle study addresses an hypothesis derived from previous studies, that chemical or physical aspects of berry cuticle development contribute to resistance. The proteomics screen aims to generate new hypotheses for future studies, and relies on methods designed to investigate a highly diverse population. The characterization of ontogenic resistance in this population will be discussed, and significant molecular and biochemical patterns correlating to the gain of resistance will be presented.