Abstract
European plum (Prunus domestica L.) is an ancient domesticated species cultivated in temperate areas worldwide whose genetic structure has been scarcely analyzed to date. In this study, a broad representation of Spanish European plum germplasm collected in Northeastern Spain and a representative set of reference cultivars were compared using nuclear and chloroplast markers. The number of alleles per locus detected with the SSR markers ranged from 8 to 39, with an average of 23.4 alleles, and 8 haplotypes were identified. Bayesian model-based clustering, minimum spanning networks, and the analysis of molecular variance showed the existence of a hierarchical structure. At the first level, two genetic groups were found, one containing ‘Reine Claude’ type reference cultivars altogether with ca. 25% of local genotypes, and a second one much more diverse. This latter group split in two groups, one containing most (ca. 70%) local genotypes and some old Spanish and French reference cultivars, whereas the other included 24 reference cultivars and only six local genotypes. A third partition level allowed a significant finer delineation into five groups. As a whole, the genetic structure of European plum from Northeastern Spain was shown to be complex and conditioned by a geographical proximity factor. This study not only contributes to genetic conservation and breeding for this species at the national level, but also supports the relevance of undertaking similar tasks of collection and characterization in other unexplored areas. Moreover, this kind of research could lead to future coordinated actions for the examination of the whole European plum diversity, to define conservation strategies, and could be used to better understand the genetic control of traits of horticultural interest through association mapping.
Highlights
The biological origin of European plum (Prunus domestica L.), a hexaploid species (2n = 6x = 48), is still controversial and remains uncertain [1, 2]
This study considers 120 P. domestica accessions collected in areas from Northeastern Spain and an additional set of 46 cultivars used as a reference (Table 1)
The study of amplification products showed that eight out of the 21 SSR markers used were problematic in terms of absence of amplification product, insufficient fluorescence signal, low Genetic diversity and structure of Spanish Prunus domestica germplasm level of polymorphism or complex scoring pattern and, as a consequence, were excluded from subsequent analyses (S2 Table)
Summary
Genetic diversity and structure of Spanish Prunus domestica germplasm to the Prunus genus within the Prunoideae subfamily of Rosaceae [7, 8] This species probably originated at Western Asia, in the area south to the Caucasus Mountains and the Caspian Sea, which later travelled into Western Europe [8, 9]. Stone remnants indicate that P. domestica L. was used by humans, at least, 6,000 years ago, and it is known to have been widely cultivated in Roman times. This long history of domestication has resulted in a rich diversity of morphological characteristics and crop aptitudes [8]
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