Genetic diversity among and within tomato (Solanum lycopersicum L.) landraces grown in Southern Italy

Abstract

Landraces can be defined as locally adapted cultivated forms of domesticated plant species that have distinctive traits resulting from both environmental adaptation and farmer selection. In tomato (Solanum lycopersicum L.), they are important for preserving genetic diversity and as a potential source of adaptive traits that are not found in contemporary commercial varieties. In this work, we analyzed the genetic variability within and between 16 tomato landraces originating in Southern Italy, a secondary center of diversity. We used the highly discriminant (GATA)4 DNA fingerprinting to assess genetic homogeneity, relationship, differentiation, and structure, as well as to infer the occurrence of possible contaminant or admixed genotypes. Within-landrace variability was found in a third of the landraces. The population structure (without using predefined groups) indicated in different instances, a correspondence between fruit type and landraces’ clusters. The results of multivariate and Bayesian analyses showed a low frequency of possible admixed or contaminant genotypes. Moreover, the quantification of intra-landrace variability allowed to estimate the potential loss of diversity in storing tomato landraces as pure lines. Finally, issues related to possible contamination of the germplasm also imply that more thorough assessment of variability is required not only to store genuine diversity but also to exploit tomato landraces in breeding programs.