Contributions of the VitisGen2 project to grapevine breeding and genetics

The VitisGen projects (2011-2022) have improved the tools available for breeding new grapevine cultivars with regional adaptation, high quality, and disease resistance. VitisGen2 (the second project in the series) was a multi-state collab-oration (USDA-Geneva, New York; University of California, Davis; USDA-Parlier, California; Cornell University; Missouri State University; University of Minnesota; South Dakota State University; Washington State University; North Dakota State University; and E&J Gallo, California) to develop im-proved genetic mapping technology; to identify useful DNA marker-trait associations; and to incorporate marker -assist-ed selection (MAS) into breeding programs. A novel genetic mapping platform (rhAmpSeq) now provides 2000 + mark-ers that are transferable across the Vitis genus. rhAmpSeq has been used in California, New York, Missouri, and South Dakota to identify new QTL for powdery and downy mil-dew resistance. In addition, fruit/flower traits that would normally take years to phenotype have been associated with predictive markers accessible from seedling DNA (e.g. malate metabolism, anthocyanin acylation, bloom phenol-ogy and flower sex). Since 2011, the project has used MAS to screen thousands of grape seedlings from public breed-ing programs in the United States and has produced "Ren-Stack" public domain lines to enable simultaneous access to 4 or 6 powdery mildew resistance loci from single source genotypes. High-throughput phenotyping for powdery and downy mildew resistance has been revolutionized with the Blackbird automated-imaging system powered by artificial intelligence for image analysis. Affordable DNA sequenc-ing along with phenotyping innovations are transforming grapevine breeding.