Juglans regia is an important perennial crop cultivated for its high-quality nuts and wood. It is generally believed that J. regia survived and expanded in almost completely isolated stands in Asia after the last glaciation. Humans subsequently dispersed J. regia through cultural expansion and trade. We evaluated the spatial genetic structure and genetic diversity of 2,929 J . regia samples from 150 populations using 14 Simple Sequence Repeats (SSRs) markers. Our study revealed that regions with the highest genetic diversity included Southern Asia, Western Asia, Western Europe, and China, as illustrated using a Geostatistical Inverse Distance Weighting (IDW) interpolation of observed heterozygosity (H O ), expected (HE) heterozygosity (H E ), percentage of polymorphic loci (PPL), the total number of alleles (N A ) , and Allelic richness (R S ) in Arc Geographic Information System (ArcGIS). The ecological Niche Model (ENM) showed J. regia had a high probability of association with Central Asian and Eastern Asian habitats. Population genetic structure, phylogeny, and Principal Coordinate Analysis (PCoA) identified three genetic groups corresponding to three geographic sources. Turkish and Georgian populations served as a bridge between Asian populations and Europe populations. We suggest that J. regia evolved in central Asian mountain ranges ~ 65 million years ago (Mya) and dispersed across Eurasia during climate shifts (~ 65 to 3Mya). The population contracted into multiple refugia during the Last Glacial Maximum. The current distribution of J. regia across Eurasia was shaped by the cumulative effects of contraction or expansion of different refugia and human exploitation after LGM.

Walnut (Juglans) species are economically important hardwood trees cultivated worldwide for both edible nuts and high-quality wood. Broad-scale assessments of species diversity, evolutionary history, and domestication are needed to improve walnut breeding. In this study, we sequenced 309 walnut accessions from around the world, including 55 Juglans relatives, 98 wild Persian walnuts (J. regia), 70 J. regia landraces, and 86 J. regia cultivars. The phylogenetic tree indicated that J. regia samples (section Dioscaryon) were monophyletic within Juglans. The core areas of genetic diversity of J. regia germplasm were southwestern China and southern Asia near the Qinghai-Tibet Plateau and the Himalayas, and the uplift of the Himalayas was speculated to be the main factor leading to the current population dynamics of Persian walnut. The pattern of genomic variation in terms of nucleotide diversity, linkage disequilibrium, single nucleotide polymorphisms, and insertions/deletions revealed the domestication and selection footprints in Persian walnut. Selective sweep analysis, GWAS, and expression analysis further identified two transcription factors, JrbHLH and JrMYB6, that influence the thickness of the nut diaphragm as loci under selection during domestication. Our results elucidate the domestication and selection footprints in Persian walnuts and provide a valuable resource for the genomics-assisted breeding of this important crop.

This dataset is the result of a survey conducted during the 2012-2016 COST Action FP1202 (MaP-FGR): Strengthening conservation: a key issue for adaptation of marginal/peripheral populations of forest trees to climate change in Europe. It contains the name, location and other relevant information of 577 forests that are considered as marginal of peripheral by forest experts. Information (as specified in the read-me file) includes among others: Genus, Species, Country, Name of marginal population, Latitude, Longitude, Elevation, Type of marginality, Silvicultural system, Protection status, Threat status, and genetic and phenotypic trait data availability This dataset can be used to, e.g., test effects of marginality on biological and genetic traits, compare expert knowledge with statistics-based indicators, raise awareness of the importance of marginal populations for conservation and sustainable use.

Abstract A biocultural diversity approach integrates plant biology and germplasm dispersal processes with human cultural diversity. An increasing number of studies have identified cultural factors and ethnolinguistic barriers as the main drivers of the genetic diversity in crop plants. Little is known about how anthropogenic processes have affected the evolution of tree crops over the entire time scale of their interaction with humans. In Asia and the Mediterranean, common walnut (Juglans regia L.) and sweet chestnut (Castanea sativa Mill.) have been economically and culturally important crops for millennia; there, in ancient times, they were invested with symbolic and religious significance. In this study, we detected a partial geographic congruence between the ethno‐linguistic repartition of human communities, the distribution of major cognitive sets of word‐related terms, and the inferred genetic clusters of common walnut and sweet chestnut populations across Eurasia. Our data indicated that isolation by distance processes, landscape heterogeneity and cultural boundaries might have promoted simultaneously human language diversification and walnut/chestnut differentiation across the same geographic macro‐regions. Hotspots of common walnut and sweet chestnut genetic diversity were associated with areas of linguistic enrichment in the Himalayas, Trans‐Caucasus, and Pyrenees Mountains, where common walnuts and sweet chestnuts had sustained ties to human culture since the Early Bronze Age. Our multidisciplinary approach supported the indirect and direct role of humans in shaping walnut and chestnut diversity across Eurasia from the EBA (e.g., Persian Empire and Greek–Roman colonization) until the first evidence of active selection and clonal propagation by grafting of both species. Our findings highlighted the benefit of an efficient integration of the relevant cultural factors in the classical genome (G) × environmental (E) model and the urgency of a systematic application of the biocultural diversity concept in the reconstruction of the evolutionary history of tree species.

Black locust Robinia pseudoacacia L. is a fast growing tree, used in forest establishment. It is an economically important tree for tool production, obtaining timber and fuel as well as an important constituent element for landscapes. Though the tree is abundant, information on genetics, physiology, biology, wood quality and adaptability to different ecological conditions is limited and fragmented. The aim of this research was to study physiological and biochemical adaptation by comparing two black locust Clones that showed different responses to drought. The two Clones were exposed to different water regimes: Medium Stress and High Stress (50 and 25 % of water supplied to control). Physiological and biochemical measurements were made. Stress affected negatively the growth of both Clones. The effect of different stress intensity (MS and HS treatments) was observed on stem shape. When re-watered the stem showed partial recovery. Net photosynthesis rate in drought period did not show marked difference between the Clones. After soil rehydration both Clones recovered photosynthesis level. The Clones 1 did not show differences in osmotic potential when comparing Control and MS or HS trees. The Clone 2 showed increased osmotic potential in relation to stress intensity. The maximum potential in Clone 2 was comparable to the values for Clone 1. Amino acids, especially proline, increased in drought. The soluble sugars increased during the stress period in the stems of Clone 2. The increased absence of osmolytes increase in Clone 1 could be due to the absence of adaptive mechanism. Alternatively, osmolytes concentration was already too high to be increased more by drought. Different osmotic potential and changes during drought can be related to the growth during tree life. Selection of Clones according to osmolyte index could to select better trees for different climate zones.

Common walnut (Juglans regia L) is an economically important species cultivated worldwide for its high-quality wood and nuts. It is generally accepted that after the last glaciation J. regia survived and grew in almost completely isolated stands in Asia, and that ancient humans dispersed walnuts across Asia and into new habitats via trade and cultural expansion. The history of walnut in Europe is a matter of debate, however. In this study, we estimated the genetic diversity and structure of 91 Eurasian walnut populations using 14 neutral microsatellites. By integrating fossil pollen, cultural, and historical data with population genetics, and approximate Bayesian analysis, we reconstructed the demographic history of walnut and its routes of dispersal across Europe. The genetic data confirmed the presence of walnut in glacial refugia in the Balkans and western Europe. We conclude that human-mediated admixture between Anatolian and Balkan walnut germplasm started in the Early Bronze Age, and between western Europe and the Balkans in eastern Europe during the Roman Empire. A population size expansion and subsequent decline in northeastern and western Europe was detected in the last five centuries. The actual distribution of walnut in Europe resulted from the combined effects of expansion/contraction from multiple refugia after the Last Glacial Maximum and its human exploitation over the last 5,000 years.

Common walnut (Juglans regia L) is an economically important species cultivated worldwide for its wood and nuts. It is generally accepted that J. regia survived and grew spontaneously in almost completely isolated stands in its Asian native range after the Last Glacial Maximum. Despite its natural geographic isolation, J. regia evolved over many centuries under the influence of human management and exploitation. We evaluated the hypothesis that the current distribution of natural genetic resources of common walnut in Asia is, at least in part, the product of ancient anthropogenic dispersal, human cultural interactions, and afforestation. Genetic analysis combined with ethno-linguistic and historical data indicated that ancient trade routes such as the Persian Royal Road and Silk Road enabled long-distance dispersal of J. regia from Iran and Trans-Caucasus to Central Asia, and from Western to Eastern China. Ancient commerce also disrupted the local spatial genetic structure of autochthonous walnut populations between Tashkent and Samarkand (Central-Eastern Uzbekistan), where the northern and central routes of the Northern Silk Road converged. A significant association between ancient language phyla and the genetic structure of walnut populations is reported even after adjustment for geographic distances that could have affected both walnut gene flow and human commerce over the centuries. Beyond the economic importance of common walnut, our study delineates an alternative approach for understanding how the genetic resources of long-lived perennial tree species may be affected by the interaction of geography and human history.

Background and Purpose: Black locust (Robinia pseudoacacia L.) is a valuable species native to North America and today widely planted throughout the world for biomass production. In Hungary, where Robinia has great importance in the forest management, the clones have been selected for plantations on good, medium and poor quality sites. To conserve the identity, superior clones are vegetatively propagated by root cuttings. At times the collection of root cuttings can cause uncertainty for clonal identity because of the overlap of roots from neighboring plants. This can occur especially when the repository is damaged from severe environmental accidents and the planting layout has been lost. The aim of this study has been to verify by molecular markers the diversity or identity of black locust clones by root cuttings harvested in a damaged trial.Materials and Methods: Root cuttings of 91 clones belonging to five cultivars were collected in a trial severely damaged by storms and flooding periods. The obtained plantlets were analyzed with nine microsatellite (SSR) markers and the genetic identity/diversity within and among the plants was tested using the software GenAlEx version 6.Results: Multilocus genotypes (MLG) and the Paetkau's assignation test (1985) revealed genetic variability among the samples: the analyzed plantlets were grouped in four classes instead of the five expected. In addition, 6 unique genotypes have been detected.Conclusions: This study remarks problems that may arise during the harvest of Robinia's root cuttings, especially when the planting layout has been confused. Molecular analyses can be successfully used to control the germplasm before its sale as guaranty for nurseries, farmers and stakeholders.

Central Asia where walnut was grown since Oligocene was recognized as a center of its origin and distribution. Now in Uzbekistan, J. regia stands occupy three areas geographically isolated from each other by more than 250 km: Western Tien-Shan, Nurata and Hissar. Survey expeditions were performed mainly in natural thickets, half-wild plantations and single tree in "dehkan" gardens. Morphological descriptors, biochemical and genetic markers were used to evaluate the biodiversity of walnut for conservation and developmental use. Trees from 20-30 years up to over-matured (300-500 years old) were considered. A variety in nuts was recorded: as to weight (5 up to 25 g) and other morphological and biochemical attributes. Lipid in kernels contain PUFA for more of 80%. Vitamin E was also extracted in the range 0.1-1.5 mg/g of kernel. Using 14 SSR primers, DNA fragments of different size were obtained with variable number of alleles in the walnut trees sampled. Spatial genetic structure analysis divided the Uzbek trees into three groups that partially corresponded to the growing area of trees. Studies in progress preliminary indicated that the genetic structure of Uzbek walnut partially overlapped to trees from outside the country. The ancestors of Uzbek trees could share the origin with the nearby forests, now belonging to other countries, but in the past together identified as Turkestan, and focal point of the Silk Roads for East-West trade and migrations.

Juglans nigra and Juglans regia are phylogenetically divergent species. Despite the economic interest in Juglans × intermedia (J. nigra ×  J. regia), walnut hybridization is rare under natural conditions and still difficult using controlled pollination. Here, we evaluated some reproductive mechanisms that may prevent successful natural hybridization. The study of flowering phenology of 11 J. nigra and 50 J. regia trees growing in a plantation provided information regarding the opportunity for interspecific crosses. Variation in flower size, pollen quality of putative donors, and variation in seed yield and rate of hybrid production among putative maternal trees were examined. DNA fingerprinting and parentage analyses based on nine microsatellites permitted the identification of hybrids and hybridogenic parent. Our data indicated that overlap occurred between the staminate flowering of protogynous J. regia and the beginning of pistillate flowering of protogynous J. nigra. Differences in floral size were computed between walnut species. Only three hybrids among 422 offspring of eleven J. nigra progenies were identified. Interspecific hybridization involving pollination of one early-flowering-protogynous J. nigra by three protogynous J. regia trees was detected. The correct development of J. regia male gametophytes, high pollen viability (86.5 %), and germination (57.6 %) ruled out the possibility that low pollen quality contributed to depressed hybrid production. Our findings indicated that these two species tended to remain reproductively isolated. The substantial disjunction in flowering time and additional prezygotic barriers such as differences in floral size and conspecific pollen advance may affect interspecific gene flow between J. regia and J. nigra.

Juglans nigra and Juglans regia are two highly economically important species for wood and fruit production that are susceptible to anthracnose caused by Gnomonia leptostyla. The identification of genotypes resistant to anthracnose could represent a valid alternative to agronomic and chemical management. In this study, we analyzed 72 walnut genotypes that showed a variety of resistance phenotypes in response to natural infection. According to the disease severity rating and microsatellite fingerprinting analysis, these genotypes were divided into three main groups: (40) J. nigra resistant, (1) J. nigra susceptible, and (31) J. regia susceptible. Data on leaf emergence rates and analysis of in vivo pathogenicity indicated that the incidence of anthracnose disease in the field might be partially conditioned by two key factors: the age and/or availability of susceptible leaves during the primary infection of fungus (avoidance by late flushing) and partial host resistance. NBS profiling approach, based on PCR amplification with an adapter primer for an adapter matching a restriction enzyme site and a degenerate primer targeting the conserved motifs present in the NBS domain of NBS-LRR genes, was applied. The results revealed the presence of a candidate marker that correlated to a reduction in anthracnose incidence in 72 walnut genotypes.

Life history traits, historic factors, and human activities can all shape the genetic diversity of a species. In Italy, walnut (Juglans regia L.) has a long history of cultivation both for wood and edible nuts. To better understand the genetic variability of current Italian walnut resources, we analyzed the relationships among the genetic structure of local walnut populations (inferred by SSR markers) and human migrations along ancient routes, using the territory of Royal Tratturo Candela-Pescasseroli (RT) as a case study. Sixteen J. regia provenances were collected along RT and compared with 13 Italian provenances and the landrace Sorrento. Although the level of SSR polymorphism we observed was moderately high, AMOVA revealed that most of the diversity was located within individuals (92.58%), and geographical differentiation was low (D (est) = 0.076). Evidence for human-mediated domestication bottleneck events was detected in about 95% of walnut provenances. A Bayesian approach divided 456 walnut samples into three clusters: (1) Sorrento genotypes, (2) trees from the island of Sicily, and (3) the remaining germplasm. The UPGMA tree based on Nei's distances distinguished northeastern provenances and weakly grouped 12 of 16 provenances of RT. The observed genetic differences derived mainly from gradations in allele frequencies. Separation of the Sicilian provenance from the mainland may be explained in terms of founder effects and prolonged geographic isolation. Two contrasting forces, selection, and frequent inter-regional transfer of propagules, appear to drive the patterns of genetic variability for J. regia.

The genus Robinia is a small group of about 10 species of trees and shrubs indigenous only to NorthAmerica. Two species are endemic to Mexico, one being confined to south-western part of the country, while the rest are endemic to the south-eastern part of USA. Of the most important species and varieties of genus Robinia, Robinia x ambigua Poir.(Robinia viscosa x R. pseudo-acacia)-pink locust can be considered as the most significant one for bee-forage and decorative planting. In this paper a generative propagation method is presented for pink locust.

This review focuses on the pollen biology of Juglans, and in particular Juglans nigra (Eastern Black walnut) and Juglans regia (Persian or English walnut), which are economically important species in Europe, Asia and North America. Both species are monoecious, heterodichogamous and wind -pollinated Their mating system is predominantly outcrossing, although under particular environmental conditions self-pollination is possible. Hybrids between the two species, Juglans x intermedia (Carr) can occur naturally, although they often have reduced fecundity. Compared to the parental species, most J x mtermedia (J nigra x J. regia) hybrids show increased vegetative vigor, distinct disease resistance, high wood quality, and greater winter-hardiness. For these reasons here is great demand for J. x intermedia for forestry, especially in Northern Europe. We review several aspects of Juglans pollen biology that frustrate the production of J x inntemedia and limit the progress of researchers and plant breeders who work with this genus. We also discuss the ways in which scientists and breeders are working to overcome problems related to pollen storage and viability testing, pistillate flower abscission (PFA), fertilization and embryogenesis in Juglans, and the use of microsatellites to monitor gene flow, ploidy, parentage, and hybridogenesis all with an eye toward practical solutions to the current shortage of J x intermedia for research and applied forestry.

Scattered broadleaved tree species such as ashes (Fraxinus excelsior L. and Fraxinus angustifolia Vahl.), black alder (Alnus glutinosa (L.) Gaertn.), birches (Betula pendula Roth. and Betula pubescens Ehrh.), elms (Ulmus glabra Huds., Ulmus laevis Pall. and Ulmus minor Mill.), limes (Tilia cordata Mill. and Tilia platyphyllos Scop.), maples (Acer campestre L., Acer platanoides L. and Acer pseudoplatanus L.), wild service tree (Sorbus domestica L. and Sorbus torminalis L. Crantz), walnuts (Juglans regia L., Juglans nigra L. and hybrids) and wild cherry (Prunus avium L.) are important components of European forests. Many species have high economic, environmental and social values. Their scattered distributions, exacerbated in many cases by human activity, may make them more vulnerable to climate change. They are likely to have less ability to reproduce or adapt to shifting climate space than more widespread species. The general impacts of climate change on these scattered species are reviewed. Some specific risks and opportunities are highlighted for each species, although there is considerable uncertainty and therefore, difficulty in quantifying many specific risks and/or impacts on scattered broadleaved tree species.

Una attenzione crescente viene rivolta alla conservazione della biodiversita vegetale al di fuori degli ambienti naturali, sia per le specie di interesse agronomico, sia per la flora spontanea, anche in attuazione agli obblighi previsti dalla Convenzione sulla Diversita Biologica (Rio de Janeiro, 1992). Quest’ultima, infatti, all’articolo 9 “Conservazione ex situ” indica una serie di misure da adottare per il recupero, la ricostituzione e la reintroduzione di specie minacciate a completamento delle strategie di conservazione in situ. Inoltre, il quarto report dell’Intergovernmental Panel on Climate Change (2007) indica la conservazione ex situ tra le principali azioni di adattamento degli ecosistemi ai cambiamenti climatici in corso. La conservazione in situ (aree di origine) e quella on farm (nelle aree di coltivazione) sono prioritarie, ma quella ex situ (banche genetiche, collezioni, orti botanici, ecc.) si rende indispensabile in quei casi, e sono tanti, in cui le prime due, per motivi diversi, sono difficili da realizzare. Attualmente, infatti, le molteplici pressioni che agiscono sugli habitat possono in alcuni casi minacciare la sopravvivenza di una o piu specie o l’integrita e la funzionalita di interi ecosistemi, tanto da rendere difficile attuare strategie di conservazione in situ. In questi casi, solo le tecniche ex situ possono garantire la conservazione della variabilita genetica del germoplasma (semi, polline, parti di pianta, spore, ecc.) e quindi la rigenerazione, riproduzione e/o moltiplicazione delle specie da conservare. La conservazione ex situ ha inoltre un ruolo indispensabile per la ricerca e il miglioramento genetico al fine di promuovere un utilizzo sostenibile del germoplasma disponibile.Solo pochi anni fa, nel 2004, la maggior parte dei Paesi del mondo ha ratificato il Trattato Internazionale della FAO sulle risorse fitogenetiche per l’alimentazione e l’agricoltura che, inter alia, considera la conservazione ex situ come uno dei pilastri essenziali per assicurare a lungo termine la sostenibilita e la sicurezza alimentare e ambientale.

Juglans nigra and Juglans regia are economically important species in Europe, Asia and North America. Natural hybrids between the two species, known as Juglans x intermedia (Carr), are valued for timber production. We tested ten nuclear microsatellite markers to (1) identify new J. x intermedia hybrids and characterize their parentage species J. regia and J. nigra (2) detect J. nigra genotypes with a spontaneous crossing ability with J. regia in a mixed Italian population. This study was also designed to confirm the transferability of ten black walnut SSR loci to Persian walnut All ten microsatellites amplified in both species, producing fragments of variable size; eight (7.14%) were common, 68 (60.7%) amplified in J. nigra and 36 (32.1%) in J. regia only (private alleles). Indices of genetic diversity revealed high level of variability. The Principal Coordinate Analysis on the basis of total 112 alleles divided the total sample set into three main groups: J. nigra, J. regia and J. x intermedia hybrids. Performing the microsatellite fingerprinting, a triploid hybrid plant with two genome parts of J. nigra and one part of J. regia was identified. The cytological analysis proved this triploid state showing 48 somatic chromosomes. The mother testing analysis of the 7 diploid hybrids by exclusion method indicated one putative hybridogenic mother plants. The sequence analysis of amplified fragments confirmed the cross-species amplification of SSR. Inter-specific differences between alleles were due not only to simple changes in the number of repeats but also to mutations in the flanking regions.