Single Nucleotide Polymorphisms as Practical Molecular Tools to Support European Chestnut Agrobiodiversity Management

Abstract

European chestnut orchards are multifunctional agroforestry systems with a key role in environmental management. Their biodiversity is at risk of erosion and farmers do not have enough tools to protect and valorize traditional ecotypes. In particular, cost effective and reliable molecular markers for cultivar identification are lacking. The aim of this research was to develop a new molecular tool for varietal identification in European chestnuts. A set of cultivars was preliminarily characterized to evaluate the range of genetic diversity using random amplified polymorphic DNA (RAPD) markers. The genetic distances indicated a sufficiently wide variability range among tested genotypes and confirmed they were suitable for our goal. A single nucleotide polymorphism (SNP) mining within 64 expressed sequence tags (EST), covering all the linkage groups, was performed by high-resolution melting (HRM) and validated by target resequencing. Fifty-six SNPs were retrieved by monitoring the variability present on the whole set of considered cultivars in loci uniformly distributed on the genome. A subset of 37 SNPs was finally transformed into kompetitive allele-specific PCR (KASP) markers that were successfully evaluated for varietal discrimination. Three assays (C1083, G0115 and A5096) were identified as necessary and sufficient for distinguishing among the tested cultivars. The developed tools can be effectively exploited by stakeholders for improving the management of the European chestnut genetic resources.