The “green gold” @fem: assessing grapevine germplasm diversity to crossbreed the varieties of the future

Abstract

Context and purpose of the study. To date over 3,000 grapevine accessions have been collected at Fondazione Edmund Mach (FEM). The responsibility is not only to conserve the biodiversity heritage but also to valorize this “green gold” through the study of its genotypic and phenotypic diversity, so as to exploit this information for the development of new superior varieties.

Material and methods. The germplasm is grafted onto SO4 rootstock (except rootstock varieties), and is generally maintained in treated fields, with untreated vineyards dedicated to genotypes under the biotic stress resistance crossbreeding program. The nine reference microsatellites were used to genetically characterize the germplasm, defining unique profiles and parent-offspring (PO) relationships. Robust R-loci associated markers were adopted to screen putative resistant genotypes, and SNParray characterization is oncoming. Up to 80 phenotypic variables were collected across at least three seasons, and all information is hosted in the new FAIR FEM Vitis Database.

Results. A total of 2,116 unique genetic profiles were identified, along with 57 somatic variants of 30 varieties (cépages). The Vitis International Variety Catalogue (VIVC) served as a reference to determine known profiles, revealing 928 unknown and therefore uncharted genotypes that will enrich the asset of the grapevine community. Putative PO relationships were identified for 1,873 genotypes, 898 belonging to the unknown cohort. Through reciprocal relationship investigation, families within the germplasm were generated, with the largest encompassing 1,749 profiles. Phenology (from wooly bud to ripening) and fertility metrics were filed for the entire collection, with ongoing surveys to assess flower sex and emergent diseases. Biotic stress resistance was recorded using OIV descriptors for cluster and leaf downy mildew, powdery mildew, black rot; leaf erinosis, phylloxera, flavescence dorée; cluster gray mold; and five viroses. For the phase II crossbreeding selections, data were also collected on 50 ampelography-related OIV descriptors, ripening curve (from veraison to 18°Brix), plant yield, cluster and berry weight, berry and must anthocyanin and total polyphenol content.

This work uncovers the FEM germplasm diversity, exploring trait distribution and unique trends to inform grapevine crossbreeding programs towards the development of improved parental-lines and new disease resistant and climate resilient varieties.