Deciphering phenotypic diversity within a tomato landrace: the ‘Pomodoro di Sorrento’ case study

Abstract ‘Pomodoro di Sorrento’ – PS ( Solanum lycopersicum L.) is a traditional Italian tomato landrace which is highly appreciated for its large multilocular pink fruits and distinctive organoleptic quality. In this study, a collection of 10 PS accessions was characterized for morphological, agronomic, and fruit quality traits and compared with three related Italian tomato landraces (‘Cuore di Bue’, ‘Pera di Abruzzo’, and ‘Pera di Albenga’). The objectives were to (i) define the phenotypic identity of the PS landrace, (ii) assess intra-landrace variability, and (iii) identify key traits for germplasm management and valorization. Multivariate analyses revealed a clear phenotypic distinctiveness of PS compared to the reference landraces while highlighting substantial diversity within the PS collection. Fruit morphology and quality traits emerged as the main features defining the PS ideotype. PS accessions maintained distinct trait combinations and were grouped into three phenotypic clusters by hierarchical clustering. A stepwise discriminant analysis identified pH, a*/b* color ratio, soluble solids content, and glucose concentration as the most informative variables, capturing much of the phenotypic structure of the collection. These results demonstrate that a limited set of quality-related traits can effectively support the classification of newly collected materials and facilitate local germplasm management. Overall, the PS collection represents a coherent, diverse, and non-redundant reservoir of variability. The proposed phenotypic framework provides valuable tools for germplasm conservation, characterization, and valorization while offering a foundation for future breeding efforts aimed at combining varietal typicity, fruit quality, and agronomic performance.