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The genetic diversity of pear local varieties prospected in mountainous areas from Northeastern Spain (Pyrenees and Iberian Cordillera) is not well known so far. In this study, an overall set of 252 accessions (178 prospected in mountainous areas from Aragon and a diverse set of 74 reference cultivars) was analyzed using 14 SSRs in order to estimate its genetic diversity and to identify the genetic structure and relationships among the pear germplasm studied. A total of 251 distinct alleles were successfully amplified with an average of 17.9 alleles per locus and with a wide genetic diversity (mean expected heterozygosity of 0.82). In total, 228 unique genotypes were identified and 210 genotypes were represented by a single accession indicating a situation of extreme vulnerability of these pear genetic resources held in the CITA collection. An amount of 32.9% of accessions were considered triploids displaying three alleles at least into two loci. Genetic analyses performed by a model-based Bayesian procedure, principal coordinate analysis and analysis of molecular variance supported the presence of a genetic stratification with the existence of four sub-groups among the accessions, with a highly significant differentiation (FST = 0.132; p < 0.001). These results shed light on the characterization and genetic relatedness between these local accessions and currently cultivated pear cultivars and highlight the importance to safeguarding this diversity that might be essential for new breeding programs. [ABSTRACT FROM AUTHOR]

The article describes the Monrepos plum rootstock for cherries. This rootstock was bred at the Agri-Food Research and Technology Center of Aragón (CITA) in Zaragoza, Spain. Furthermore, this rootstock was selected from an open-pollinated population of Myrobolan. An overview of the rootstock's origin and performance is provided.

Spanish pear germplasm collections are crucial for preservation, research, and breeding efforts. However, genetic diversity and structure is unknown at national level. A coordinated national project analyzed 1251 accessions from 7 Spanish pear collections using an internationally recognized set of 14 SSRs to enhance the utilization of these collections. Key findings included the identification of 760 unique genotypes (490 diploids and 270 triploids). Notably, genotypes represented by a single accession accounted for 49% of the total, indicating high vulnerability of this material. Using a Bayesian clustering method revealed two main genetic groups, G1 containing most foreign cultivars and G2 retaining local Spanish cultivars, which were further divided into two other subgroups using a nested approach, revealing moderate but significant differentiation among them. The populations were renamed according to the origin of the reference samples assigned to each group as 'South' (G1.1), 'Western Europe-1' (G1.2), 'Western Europe-2' (G2.1) and 'No-Pyrus communis' (G2.2). The results led to the creation of a 'generalist' collection, aiming to maximize genetic diversity representativeness, starting with 68 genotypes but expanding to 111 to achieve better allele recovery. This core collection is a valuable resource for genetic studies and conservation, enhancing efforts to preserve pear biodiversity., (© 2024. The Author(s).)