Profiling the Diversity of Sweet Pepper ‘Peperone Cornetto di Pontecorvo’ PDO (Capsicum annuum) through Multi-Phenomic Approaches and Sequencing-Based Genotyping

Abstract

The sweet pepper (Capsicum annuum) ‘Peperone Cornetto di Pontecorvo’ is a prominent local variety at risk of genetic erosion cultivated in the Latium region (Italy). This horn-shaped landrace is recognized for its high digestibility due to the thinness of the skin and has been granted the Protected Designation of Origin (PDO) mark since 2010. Nowadays, different accessions are claimed as ‘Peperone Cornetto di Pontecorvo’ and no assay has been conducted to determine authenticity. In this study, 14 ‘Peperone Cornetto di Pontecorvo’ accessions and 7 similar horn-type peppers were investigated for their morpho-agronomic performance and chemical composition. Digital fruit imaging was implemented as a tool to pinpoint with high accuracy the morphometric parameters of berries. In total, 52 traits were scored. The multivariate analysis revealed different clusters that separated ‘Peperone Cornetto di Pontecorvo’ from similar types. The weight and size of fruits, as well as the content of soluble solids, were the most discriminating factors among the cultivars studied. Genomic fingerprinting was performed using ddRAD sequencing, yielding a total of a total of 120 million raw sequences and 2196 high-quality SNPs. Both Bayesian and hierarchical clustering analyses confirmed the existence of two different (K = 2) sub-populations separating ‘Peperone Cornetto di Pontecorvo’ accessions from similar types, thus highlighting a high membership (qi > 0.97) coefficient for accessions cultivated in the Pontecorvo area (Frosinone district). In addition, a direct relationship was found between the genetic diversity of cultivars and their geographical provenance, providing hints on the breeding history of local varieties in diverse rural areas. Genomic markers are revealed as a valuable tool to establish the uniqueness and distinctness of this local variety. This information will be very helpful for recovery, enhancement, and protection from possible imitations.