Assessing genetic and phenotypic diversity in pepper (Capsicum annuum L.) landraces from North-West Spain

Pepper (Capsicum annuum L.) is one of the most valuable vegetables in the world. Over the last decades, highly performing cultivars have progressively replaced the diversified and heterogeneous landraces worldwide, causing wide genetic erosion in this crop. The recovery of these ancient landraces, which might preserve alleles of agricultural interest and local adaptations, results of pivotal importance for the development of new varieties and the maintenance of a sustainable agriculture. In the present work, a collection of twenty-six landrace-derived inbred lines and three landraces from North-West Spain were evaluated for their agronomic performance and genetic diversity based on a set of twenty-seven morphological descriptors and twenty microsatellite markers. The collection featured phenotypic variability for all the studied traits, which were influenced by the location, except for the yield. The principal component analysis divided the landraces in well-defined groups, with only Arnoia, Punxin and Blanco Rosal showing some degree of overlapping. The greater part of the variance was accounted for traits such as fruit weight, pericarp thickness and fruit shape and color. The molecular analyses suggested a high level of genetic diversity within the collection and the presence of specific alleles, which were not previously detected in other Spanish pepper landraces. Multivariate and Bayesian clustering showed that landraces were primarily grouped according to their geographical origin and secondarily in agreement with the characteristics of their fruits. Six groups of landraces, with a great genetic differentiation, were clearly identified. Only the landraces Mougan and Arnoia possessed an allele associated to the pungency character.