Early ripening in cool climate viticulture varieties is mainly based on a mutation in ‘Pinot precocé noir’

Abstract

For a long time, cool climate grapevine breeding has striven for early ripening cultivars to adapt to the former climate conditions. However, due to climate change and with altered growing conditions, many current cultivars are now ripening too early and are suffering from a loss of quality and authenticity. ‘Pinot Precoce Noir’ (PPN) is an early-ripening clone of ‘Pinot Noir’ (PN) and the phenological differes phenologically by an about two weeks earlier onset of veraison. We found that the early veraison locus Ver1 on chromosome 16, previously identified in ‘Calardis Musqué’, originated from PPN. The study aimed to develop a functional SSR marker for early ripening to include this trait in marker assisted selection (MAS) and for parentage analysis.

A set of 72 important international cultivars and others with high relevance for German viticulture were investigated for their allelic status within the Ver1 locus. DNA was extracted from leaves and screened with SSR markers specifically developed for the genomic region of the Ver1. PCR fragment length for this markers was determined using a ABI 3130xl Genetic Analyzer. The functional confirmation was based on data from 12 years of veraison observations (BBCH 85) of these cultivars grown at JKI Geilweilerhof, Siebeldingen, Germany.

A single marker located within the Ver1 locus was found to have a unique fragment length on the functional Pinot-allele for the trait time of ripening. This allowed differentiation between the very early ripening PPN phenotype, the early ripening PN phenotype and the remaining varieties which were found to ripen later.

This characteristic makes the SSR marker a valuable tool to trace individual descendants of the Pinot family back to their respective founders, either the original PN or its earlier ripening PPN mutant. The screening of viticulturally relevant cultivars and the availability of a reliable veraison data set showed up its selective value. The results additionally indicate the high selective pressure of the early ripening phenotype in cool climate breeding in former decades. The marker provides a straightforward method for screening genetic resources and breeding material based on established SSR-based MAS pipelines. By enabling breeders to adapt their cool-climate viticulture breeding programmes to the challenges of climate change, the marker will help to develop climate-adapted and more resilient varieties for quality wine production in a sustainable viticulture.