1a.Objectives (from AD-416):
Improve genetic characterization of the Ren4 locus, conferring resistance to grapevine powdery mildew.
1b.Approach (from AD-416):
1) Identify additional molecular markers linked with Ren4;. 2)Genotype additional ARS-Parlier progeny segregating for Ren4 resistance to identify new recombinants;. 3)Screen and sequence BAC library from Ren4 source vine to identify chromosome inserts containing or flanking Ren4;. 4)Isolate candidate Ren4 resistance genes;. 5)Test gene function in transient and stable expression systems to detect improved resistance.
The highest quality Vitis vinifera grape cultivars are highly susceptible to powdery mildew. Grape growers desire vinifera cultivars with powdery mildew resistance for reduced inputs, which is the goal of this project. We identified molecular markers predictive of Ren4 resistance and screened a library of chromosomal fragments to identify specific sequences at the Ren4 locus. Functional analysis of the genes at the Ren4 locus is ongoing.