Castanea sativa Ancient Trees Across Europe: Genetic Diversity And Conservation Strategy

Long-living trees are witnesses of environmental changes and human interventions; these extraordinary organisms not only represent a historical, landscape and environmental heritage of inestimable value, but they also are a reserve of genetic variability which can considered as a great resource for management programs of forest species. This is the first genetic study on Italian ancient chestnut trees (Castanea sativa Mill.). Ninety-nine ancient trees including the oldest known chestnut in Europe, named ‘Cento Cavalli’, which is believed to be to be between 3,000 and 4,000 years old, were collected. For each tree, more than one sample from canopy and root suckers was collected to test for the genetic integrity of the individuals The samples were genotyped using nine nuclear microsatellite markers (nSSRs) and two chloroplast markers (cpDNA). Genetic variability indices were evaluated using GeneAlEx 6.5, GenoDive 3.0 and HP-rare software. We identified a total of 106 unique genetic profiles within the analyzed individuals. A Bayesian analysis was performed using the software STRUCTURE to unveil the genetic relationships existing between the genotyped individuals. We were able to identify a geographic pattern of genetic diversity among the old chestnut trees. In addition, the genetic similarity among the ancient trees and the close chestnut populations to was studied. A phylogeographic structure of plastid diversity was also established. Our results contribute to evaluate the European chestnut genetic resources, gave insights to its domestication history and to define the best conservation and management strategies

Monumental chestnut trees: source of genetic diversity, cultural and landscape value

The monumental trees are unique individuals of venerable age and considerable size, which represent a heritage of inestimable historical, cultural, landscape, and scientific value for the territtory. They also constitute a source of genetic diversity which confers them longevity and ability to adapt to climate and environmental changes. In this context, studies on centennial trees can be useful for interpretatiton of species history as migration events, selection and anthropogenic actiton. The aim of this research was to evaluate the genetic variability of ancient Castanea sativa trees and relate them to actual natural/naturalized populatitons and varieties in order to enhance our knowledge about the demography, cultivatiton processes and the impact of these giant trees on the genetic diversity of the species. We selected a total of 182 ancient trees from Spain and Central - Southern Italy. For each tree, more than one sample was collected to test for genetic integrity and grafing. The samples were genotyped by means of nuclear microsatellite markers and the variability of plastid DNA regitons (trnH-psbA and trnK/matK) was also tested. Using the sofware GeneALex and HPrare, we evaluated observed (Hto) and expected (He) heterozygosity, allelic richness (Ar) private allelic richness (pAr). A Bayesian analysis was performed using the sofware STRUCTURE to identify the different gene pools and gentotypes. The obtained genetic data were compared with those of natural populations and cultivars collected in the same geographic areas. Higher values of allelic richness were observed in the ancient chestnut trees, a genetic similarity of these individual trees to the natural populations was highlighted. A phylogetographic structure of plastid diversity was alsto established. Eleven genotypes were coincident with 11 cultivars in the EU database. Based on the putative age of giant trees we can hyptothesize that the grafing practice occurred in the Iberian peninsula in the 15th century and in the 17th century in Italy. This work provides new knowledge about the history and domesticatiton tof European chestnut, the results are relevant for the conservatiton and management of Castanea sativa genetic resources

Case report: Hematologic malignancies concomitant diagnosis of hairy cell leukemia and chronic lymphocytic leukemia: A rare association

A case of concomitant hairy cell leukemia (HCL) and chronic lymphocytic leukemia (CLL) in a 50- year-old man was reported. Flow cytometry and droplet digital PCR (ddPCR) were used to detect the B-Raf proto-oncogene (BRAF) V600E mutation. The HCL population was the predominant component. The patient was first treated with cladribine and then with rituximab and achieved HCL partial remission. Importantly, the high sensitivity of our flow cytometric approach allowed the detection of a small population “P3,” in addition to the typical HCL and CLL clones. The P3 clone changed over time, from an HCL-like to a CLL-like immunophenotype. This case is added to the few other cases of synchronous HCL and CLL already reported in the literature and underlines the importance of analyzing chronic lymphoproliferative disorders by highly sensitive diagnostic techniques, like the multicolor flow cytometry and ddPCR, to evaluate the possible association between HCL and CLL at diagnosis

DNA analysis of Castanea sativa (sweet chestnut) in Britain and Ireland: Elucidating European origins and genepool diversity

Castanea sativa is classified as non-indigenous in Britain and Ireland. It was long held that it was first introduced into Britain by the Romans, until a recent study found no corroborative evidence of its growing here before c. AD 650. This paper presents new data on the genetic diversity of C. sativa in Britain and Ireland and potential ancestral sources in continental Europe. Microsatellite markers and analytical methods tested in previous European studies were used to genotype over 600 C. sativa trees and coppice stools, sampled from ancient semi-natural woodlands, secondary woodlands and historic cultural sites across Britain and Ireland. A single overall genepool with a diverse admixture of genotypes was found, containing two sub groups differentiating Wales from Ireland, with discrete geographical and typological clusters. C. sativa genotypes in Britain and Ireland were found to relate predominantly to some sites in Portugal, Spain, France, Italy and Romania, but not to Greece, Turkey or eastern parts of Europe. C. sativa has come to Britain and Ireland from these western European areas, which had acted as refugia in the Last Glacial Maximum; we compare its introduction with the colonization/translocation of oak, ash, beech and hazel into Britain and Ireland. Clones of C. sativa were identified in Britain, defining for the first time the antiquity of some ancient trees and coppice stools, evincing both natural regeneration and anthropogenic propagation over many centuries and informing the chronology of the species’ arrival in Britain. This new evidence on the origins and antiquity of British and Irish C. sativa trees enhances their conservation and economic significance, important in the context of increasing threats from environmental change, pests and pathogens

Landscape genetics structure of European sweet chestnut (Castanea sativa Mill): indications for conservation priorities

Sweet chestnut is a tree of great economic (fruit and wood production), ecological and cultural importance in Europe. A large-scale landscape genetic analysis of natural populations of sweet chestnut across Europe is applied to 1) evaluate the geographic patterns of genetic diversity 2) identify spatial coincidences between genetic discontinuities and geographic barriers 3) propose certain chestnut populations as reservoirs of genetic diversity for conservation and breeding programmes. Six polymorphic microsatellite markers were used for genotyping 1608 wild trees sampled in 73 European sites. The Geostatistical IDW technique (ArcGIS 9.3) was used to produce maps of genetic diversity parameters (He, Ar, PAr) and a synthetic map of the population membership (Q value) to the different gene pools. Genetic barriers were investigated using BARRIER 2.2 software and their locations were overlaid on a Digital Elevation Model (GTOPO30). The DIVA-GIS software was used to propose priority areas for conservation. High values of genetic diversity (He) and allelic richness (Ar) were observed in the central area of C. sativa's European distribution range. The highest values of private allelic richness (PAr) were found in the eastern area. Three main gene pools and a significant genetic barrier separating the eastern from the central and western populations were identified. Areas with high priority for genetic conservation were indicated in Georgia, eastern Turkey and Italy. Our results increase knowledge of the biogeographic history of C. sativa in Europe, indicate the geographic location of different gene pools and identify potential priority reservoirs of genetic diversity

Genetic variation of Abies alba in Italy

Italy represents the southern limit of Abies alba (Mill.) (silver fir) distribution in Europe. In this region, populations are widely spread in different and isolated habitats. We used allozyme markers to study the genetic structure of ten natural populations of this species from the northern, central, and southern parts of Italy. Mean expected heterozygosity ranged from 0.129 to 0.180 and was similar to that found in other conifers. In contrast to other conifers, all the populations investigated in the present study showed a deficiency of heterozygotes. Partial inbreeding due to restricted pollen dispersal and Wahlund effect could be responsible for this situation. The central populations harboured more variability than the populations from other parts of Italy. The present study revealed significant differentiation among the investigated populations. The average genetic distance for all pair-wise comparisons between the ten populations was 0.014. Populations from the central Italy showed closer affinity to the southern populations than to the populations from the northern Italy. Our results suggest that the A. alba populations in central Italy have originated either through a postglacial blending of two different populations or through expansion of the southern populations. In addition, they confirm distinct character of populations from the southern Italy