Breeding for climate adaption should avoid a widely distibuted allele within the Ver1 veraison locus

Abstract

In the past breeding programmes for grapevine varieties for cool climate focused on developing early ripening cultivars that are better adapted to the prevailing climatic conditions. In the context of the ongoing climate change many of these cultivars are now ripen earlier than desired. This results in a decline in quality and typicity of the final wines. The very early ripening phenotype in nearly all of the developed cultivars was found to be inherited from Pinot Precoce Noir’ (PPN), an early-ripening clone of ‘Pinot Noir’ (PN). The phenological differentiation is evident in the onset of veraison about two weeks earlier, which is known to be induced by the Ver1 locus on chromosome 16, first identified in ‘Calardis Musqué’ and than traced back to PPN. Afunctional SSR marker for early ripening was developed to incorporate a new trait into the marker-assisted selection (MAS) pipeline, as well as to support the selection of cross parents. Acrucial step forward was the identification of a marker that enables the functional differentiation between PN and PPN, which could not be achieved with any of the previously available markers. To validate the marker, the allelic status of 72 important international and German cultivars was investigated within the Ver1 locus. Functional confirmation was based on 12 years of data for veraison assessments (BBCH 85) for these cultivars grown at JKI Geilweilerhof in Siebeldingen, Germany.

The identified characteristics make this marker a highly valuable tool for tracing individual Pinot descendants back to their respective founder (PN or PPN), as well as for screening viticulturally relevant cultivars. The results suggest that there was high selective pressure for the early ripening phenotype in cool-climate breeding programmes in previous decades, and that this success is primarily due to the PPN allele. The marker provides now a simple tool for screening genetic resources and selection for or against the early ripening phenotype in todays breeding programs. By helping breeders adapt their breeding programmes to future climate conditions, the marker will contribute to the development of more resilient varieties and promote sustainable viticulture and quality wine production.

Acknowledgements

The authors are grateful to the German Federal Ministry of Research, Technology and Space (BMFTR) for funding of the “SelWineQ” project (FKZ 031B1306) within the program “PLANT BREEDING RESEARCH III”.