The definition of the European Almond Core collection

The European project 068 AGRI GEN RES 870/2004 has as an aim the definition of the European almond core collection. The methodology for creation of any core collection has to define how best to select entries using complex and incomplete accession data, as well as how and when to revise these decisions over time. The acquisition of data has been based on specific varietal descriptors, including morphological, physiological, phytopathological, genetic and chemical traits, following the descriptors defined by IBPGR/Bioversity, UPOV and the ECP/GR Prunus Working Group. Newly defined traits, not included in these descriptors, have also been considered because they are very important in defining the range of variability of the species. These traits include chilling and heat requirements for blooming, the molecular markers for genotype identification and the different chemical components of the kernel, as possible parameters for defining almond quality. As a result, a strategy to define the almond core collection was identified by highlighting the main steps to achieve in the near future.Peer ReviewedPrunus amygdalus Batschcore collectiongenetic resourcesgermplasmPublishe

Impact Of Chill And Heat Exposures Under Diverse Climatic Conditions On Peach And Nectarine Flowering Phenology

The present study aims to generalize cultivar-specific tree phenology responses to winter and spring temperatures and assess the effectiveness of the Tabuenca test and various chill and heat accumulation models in predicting bloom dates for a wide range of climatic conditions and years. To this end, we estimated the dates of rest completion and blooming and correlated them with observed bloom dates for 14 peach and nectarine cultivars that were evaluated in 11 locations across Europe (Greece, France, Italy, Romania and Spain), within the EUFRIN cultivar testing trial network. Chill accumulation varied considerably among the studied sites, ranging from 45 Chill Portions (CP) in Murcia-Torre Pacheco (Spain) to 97–98 CP in Cuneo (Italy) and Bucharest (Romania). Rest completion occurred latest or was not achieved at all for some cultivars in the southern sites in Murcia. Dormancy release happened earliest in Bucharest and Cuneo, sites where heat accumulation had a strong influence on the regulation of bloom time. Blooming occurred earliest in the moderately cold regions of Lleida (Spain) and Bellegarde (France), and 7–11 days later in the warmer locations of Rome (Italy) and Naoussa (Greece), suggesting that bloom timing is strongly influenced by delayed rest completion in these locations. The Dynamic Model resulted in both more homogeneous chill accumulation across years and better predictions of bloom dates, compared with the Utah, Positive Utah and Chilling Hours models. Prediction of bloom dates was less successful for low-chill cultivars than for medium- and high-chill cultivars. Further climatic and experimental data are needed to make estimates of the climatic needs of peach cultivars more robust and to generate reliable advice for enhancing the resilience of peach production under varying and changing climatic conditions.info:eu-repo/semantics/publishedVersio

Proyecto europeo para la valorización de recursos genéticos autóctonos de almendro y avellano. Trabajos realizados en España

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Genetic assessment of the pomological classification of plum Prunus domestica L. accessions sampled across Europe

The genotyping of European fruit tree collections has helped to identify synonyms, determine parentage, reveal key specimens in the collections and provide information on the development of modern cultivars from one or several progenitors. However, studies on European plum Prunus domestica have been lagging behind, mainly because of the hexaploid chromosome number. In this co-operative study, 104 accessions conserved by 14 partners across Europe were phenotyped for 20 descriptors, and genotyped for 8 SSR loci together with 8 reference cultivars. Based on the descriptors as well as additional information supplied by the partners, as well as the scientific and horticultural literature, each accession was assigned to one of six pomological groups; (1) egg plums sensu lato (E), (2) prunes of the French d’Agen type (P/A), (3) prunes of the Central-Southeast European Zwetschen type (P/Z), (4) greengages (G), (5) mirabelles (M) and (6) bullaces, damsons and var. pomariorum (D/B). A MANOVA conducted on descriptor data revealed significant differentiation among the pomological groups as well as a geographic impact on the differentiation of local plum accessions in Europe. SSR data showed that two trios and seven pairs of genotypes had very similar allele profiles and possibly are genetically identical in spite of different accession names. An AMOVA indicated sparse genetic differentiation when accessions were grouped according to geographic origin whereas significant differences were obtained among pomological groups. A Bayesian analysis of genetic structure, as well as a discriminant analysis of principal components (DAPC), further revealed levels of similarity among and within the different pomological groups, suggesting that egg plums sensu lato (E) and greengages (G) can be referred to subsp. domestica while damsons and bullaces (D/B) but also Central-Southeast European prunes (P/Z) show more affinity to subsp. insititia. The small and possibly heterogeneous groups with mirabelles (M) and prunes of the d’Agen type (P/A) take an intermediate position suggesting a hybridogenic origin

The Expanding Menagerie of Prunus-Infecting Luteoviruses

Members of the genus Luteovirus are responsible for economically destructive plant diseases worldwide. Over the past few years, three luteoviruses infecting Prunus trees have been characterized. However, the biological properties, prevalence, and genetic diversity of those viruses have not yet been studied. High-throughput sequencing of samples of various wild, cultivated, and ornamental Prunus species enabled the identification of four novel species in the genus Luteovirus for which we obtained complete or nearly complete genomes. Additionally, we identified another new putative species recovered from Sequence Read Archive data. Furthermore, we conducted a survey on peach-infecting luteoviruses in eight European countries. Analyses of 350 leaf samples collected from germplasm, production orchards, and private gardens showed that peach-associated luteovirus (PaLV), nectarine stem pitting-associated virus (NSPaV), and a novel luteovirus, peach-associated luteovirus 2 (PaLV2), are present in all countries; the most prevalent virus was NSPaV, followed by PaLV. The genetic diversity of these viruses was also analyzed. Moreover, the biological indexing on GF305 peach indicator plants demonstrated that PaLV and PaLV2, like NSPaV, are transmitted by graft at relatively low rates. No clear viral symptoms have been observed in either graft-inoculated GF305 indicators or different peach tree varieties observed in an orchard. The data generated during this study provide a broader overview of the genetic diversity, geographical distribution, and prevalence of peach-infecting luteoviruses and suggest that these viruses are likely asymptomatic in peach under most circumstances.This study was funded by the European Union through the Horizon 2020 Marie Skłodowska-Curie Actions Innovative Training Network (H2020 MSCA-60 ITN) project “INEXTVIR” (grant agreement number 813542). The ChLVA research part was financed by the Academy of Sciences of the Czech Republic (RVO60077344). The plant indexing biological tests conducted by CTIFL were funded by INTERFEL (fresh fruit and vegetable interprofessional association). D. Safarova and M. Navratil received support from the Ministry of Agriculture of the Czech Republic, National Agency for Agricultural Research (project QK1920124). M. Glasa and D. Mihálik received support from the Slovak Research & Development Agency (project APVV-18-0005)Peer reviewe