The long-term goal of this project is to develop grape varieties that possess effective and durable resistance to powdery mildew (PM). Stacking resistance genes from multiple resistant genetic backgrounds and with the least functional redundancy is a proven breeding strategy to improve both durability and level of resistance. This strategy requires (a) the identification of multiple sources of resistance, (b) the functional characterization of the mechanisms of resistance to prioritize optimal genetic combination, and, finally, (c) marker assisted breeding to introduce the selected genes into elite varieties.
In continuation of our multi-year breeding effort, with the awarded budget in the 2015-2016 funding period we have pursued two objectives: (i) complete the genetic characterization of Ren6 and Ren7 loci from Vitis piasezkii; (ii) continue the functional characterization of resistance responses in a panel of V. vinifera accessions (Ren1, Ren6, Ren7, Ren4, Run1, Run2). We have made significant progress in both areas. A manuscript describing the genetic analysis of Ren6 and Ren7 was submitted for publication and is currently under review. We completed the characterization of Ren1 resistance responses and a manuscript describing the results was published. The experiments for the functional characterization of Ren6 and Ren7 were completed and data analysis is ongoing. We started the experiments for the functional characterization of Ren4, Run1 and Run2.