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 2016-2017 funding period we have continued the functional characterization of resistance responses activated in presence of known powdery mildew resistance loci. The experiments for the functional characterization of Ren2, Ren3, and Ren4 were completed and data analysis is ongoing. We started the experiments for the functional characterization of Run1, Run1.1, Run2.1, and Run2.2. The manuscript describing the genetic analysis of Ren6 and Ren7 and the associated markers used for introgression and stacking was published in BMC Plant Biology (Pap et al, 2016).