To learn more about the map elements, please download the "Pan-European strategy for genetic conservation of forest trees"
This distribution map has been developed by the European Commission Joint Research Centre (partly based on the EUFORGEN map) and released under Creative Commons Attribution 4.0 International (CC-BY 4.0)
Caudullo, G., Welk, E., San-Miguel-Ayanz, J., 2017. Chorological maps for the main European woody species. Data in Brief 12, 662-666. DOI: https://doi.org/10.1016/j.dib.2017.05.007
The following experts have contributed to the development of the EUFORGEN distribution maps:
Fazia Krouchi (Algeria), Hasmik Ghalachyan (Armenia), Thomas Geburek (Austria), Berthold Heinze (Austria), Rudi Litschauer (Austria), Rudolf Litschauer (Austria), Michael Mengl (Austria), Ferdinand Müller (Austria), Franz Starlinger (Austria), Valida Ali-zade (Azerbaijan), Vahid Djalal Hajiyev (Azerbaijan), Karen Cox (Belgium), Bart De Cuyper (Belgium), Olivier Desteucq (Belgium), Patrick Mertens (Belgium), Jos Van Slycken (Belgium), An Vanden Broeck (Belgium), Kristine Vander Mijnsbrugge (Belgium), Dalibor Ballian (Bosnia and Herzegovina), Alexander H. Alexandrov (Bulgaria), Alexander Delkov (Bulgaria), Ivanova Denitsa Pandeva (Bulgaria), Peter Zhelev Stoyanov (Bulgaria), Joso Gracan (Croatia), Marilena Idzojtic (Croatia), Mladen Ivankovic (Croatia), Željka Ivanović (Croatia), Davorin Kajba (Croatia), Hrvoje Marjanovic (Croatia), Sanja Peric (Croatia), Andreas Christou (Cyprus), Xenophon Hadjikyriacou (Cyprus), Václav Buriánek (Czech Republic), Jan Chládek (Czech Republic), Josef Frýdl (Czech Republic), Petr Novotný (Czech Republic), Martin Slovacek (Czech Republic), Zdenek Špišek (Czech Republic), Karel Vancura (Czech Republic), Ulrik Bräuner (Denmark), Bjerne Ditlevsen (Denmark), Jon Kehlet Hansen (Denmark), Jan Svejgaard Jensen (Denmark), Kalev Jðgiste (Estonia), Tiit Maaten (Estonia), Raul Pihu (Estonia), Ülo Tamm (Estonia), Arvo Tullus (Estonia), Aivo Vares (Estonia), Teijo Nikkanen (Finland), Sanna Paanukoski (Finland), Mari Rusanen (Finland), Pekka Vakkari (Finland), Leena Yrjänä (Finland), Daniel Cambon (France), Eric Collin (France), Alexis Ducousso (France), Bruno Fady (France), François Lefèvre (France), Brigitte Musch (France), Sylvie Oddou-Muratorio (France), Luc E. Pâques (France), Julien Saudubray (France), Marc Villar (France), Vlatko Andonovski (FYR Macedonia), Dragi Pop-Stojanov (FYR Macedonia), Merab Machavariani (Georgia), Irina Tvauri (Georgia), Alexander Urushadze (Georgia), Bernd Degen (Germany), Jochen Kleinschmit (Germany), Armin König (Germany), Armin König (Germany), Volker Schneck (Germany), Richard Stephan (Germany), H. H. Kausch-Blecken Von Schmeling (Germany), Georg von Wühlisch (Germany), Iris Wagner (Germany), Heino Wolf (Germany), Paraskevi Alizoti (Greece), Filippos Aravanopoulos (Greece), Andreas Drouzas (Greece), Despina Paitaridou (Greece), Aristotelis C. Papageorgiou (Greece), Kostas Thanos (Greece), Sándor Bordács (Hungary), Csaba Mátyás (Hungary), László Nagy (Hungary), Thröstur Eysteinsson (Iceland), Adalsteinn Sigurgeirsson (Iceland), Halldór Sverrisson (Iceland), John Fennessy (Ireland), Ellen O'Connor (Ireland), Fulvio Ducci (Italy), Silvia Fineschi (Italy), Bartolomeo Schirone (Italy), Marco Cosimo Simeone (Italy), Giovanni Giuseppe Vendramin (Italy), Lorenzo Vietto (Italy), Janis Birgelis (Latvia), Virgilijus Baliuckas (Lithuania), Kestutis Cesnavicius (Lithuania), Darius Danusevicius (Lithuania), Valmantas Kundrotas (Lithuania), Alfas Pliûra (Lithuania), Darius Raudonius (Lithuania), Robert du Fays (Luxembourg), Myriam Heuertz (Luxembourg), Claude Parini (Luxembourg), Fred Trossen (Luxembourg), Frank Wolter (Luxembourg), Joseph Buhagiar (Malta), Eman Calleja (Malta), Ion Palancean (Moldova), Dragos Postolache (Moldova), Gheorghe Postolache (Moldova), Hassan Sbay (Morocco), Tor Myking (Norway), Tore Skrøppa (Norway), Anna Gugala (Poland), Jan Kowalczyk (Poland), Czeslaw Koziol (Poland), Jan Matras (Poland), Zbigniew Sobierajski (Poland), Maria Helena Almeida (Portugal), Filipe Costa e Silva (Portugal), Luís Reis (Portugal), Maria Carolina Varela (Portugal), Ioan Blada (Romania), Alexandru-Lucian Curtu (Romania), Lucian Dinca (Romania), Georgeta Mihai (Romania), Mihai Olaru (Romania), Gheorghe Parnuta (Romania), Natalia Demidova (Russian Federation), Mikhail V. Pridnya (Russian Federation), Andrey Prokazin (Russian Federation), Srdjan Bojovic (Serbia) , Vasilije Isajev (Serbia), Saša Orlovic (Serbia), Rudolf Bruchánik (Slovakia), Roman Longauer (Slovakia), Ladislav Paule (Slovakia), Gregor Bozič (Slovenia), Robert Brus (Slovenia), Katarina Celič (Slovenia), Hojka Kraigher (Slovenia), Andrej Verlič (Slovenia), Marjana Westergren (Slovenia), Ricardo Alía (Spain), Josefa Fernández-López (Spain), Luis Gil Sanchez (Spain), Pablo Gonzalez Goicoechea (Spain), Santiago C. González-Martínez (Spain), Sonia Martin Albertos (Spain), Eduardo Notivol Paino (Spain), María Arantxa Prada (Spain), Alvaro Soto de Viana (Spain), Lennart Ackzell (Sweden), Jonas Bergquist (Sweden), Sanna Black-Samuelsson (Sweden), Jonas Cedergren (Sweden), Gösta Eriksson (Sweden), Markus Bolliger (Switzerland), Felix Gugerli (Switzerland), Rolf Holderegger (Switzerland), Peter Rotach (Switzerland), Marcus Ulber (Switzerland), Sven M.G. de Vries (The Netherlands), Khouja Mohamed Larbi (Tunisia), Murat Alan (Turkey), Gaye Kandemir (Turkey), Gursel Karagöz (Turkey), Zeki Kaya (Turkey), Hasan Özer (Turkey), Hacer Semerci (Turkey), Ferit Toplu (Turkey), Mykola M. Vedmid (Ukraine), Roman T. Volosyanchuk (Ukraine), Stuart A'Hara (United Kingdom), Joan Cottrell (United Kingdom), Colin Edwards (United Kingdom), Michael Frankis (United Kingdom), Jason Hubert (United Kingdom), Karen Russell (United Kingdom), C.J.A. Samuel (United Kingdom).
Status of Juglans regia conservation in Europe
Common walnut has a high degree of genetic diversity, but the level of genetic diversity is still not completely known (Shanjani et al., 2021). Species populations that have colonized areas postglacially are known to have lower genetic variability; this is the case with walnut populations in Europe because of their origins from a single glacial refugia (Aradhya et al., 2017). However, across its entire distribution there are two clear genetically distinct populations, one being in eastern Europe and Asia and another being in western Europe, Africa, and the Americas (Bernard et al., 2020). The populations in western Europe and the Americas have lower genetic diversity than those in eastern Europe and Asia (Bernard et al., 2020). The high genetic diversity found in the species in South Asia is because this region is the origin of common walnut.
Moroccan, Iranian, and Turkish populations have been shown to have high genetic variation both between and within populations (Tabasi et al., 2020; Yildiz et al., 2020). Wild Greek populations showed higher genetic variation within populations than between them, and native populations could not be placed within a distinct group, with more geographically distant populations being more differentiated (Christopoulos et al., 2010). This may be because populations are grown in different geographical and ecological conditions, with stands adapted to local climate conditions over a long period creating more differentiated and genetically varied populations (Christopoulos et al., 2010).
The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2024.
Breeding causes uniformity within crops, increasing genetic vulnerability to biotic and abiotic stresses. Wild populations of common walnut in Greece and Iran showed higher genetic diversity and different genetic structure to cultivated populations (Tabasi et al., 2020). Studies of cultivated walnut populations throughout Europe, the Americas, and Asia have revealed a deficiency of heterozygotes, suggesting the presence of pedigree inbreeding in cultivars to favour specific traits (Ebrahimi, Fatahi, and Zamani, 2011). Many international cultivars used in domestic production, such as those in the USA, are genetically similar, (Christopoulos et al., 2010). Within genotypes of cultivars, those with low chill requirements had a narrow genetic base compared with other populations, whereas genotypes used for wood production have high genetic variation (Shanjani et al., 2021).
In cultivation of the common walnut, superior genotypes are selected for yield, nut characteristics, cold tolerance, tolerance to blight, or late flowering. Conserving germplasm and genetic diversity is driven by the desire to use new cultivars and identify promising parents for crossbreeding in cultivation and breeding programmes (Ebrahimi, Fatahi, and Zamani, 2011). Wild populations may be a valuable resource in cultivation due to their high genetic diversity, making it important to conserve germplasm for the allelic diversity of traits, both those currently being exploited and those not yet used in breeding programmes. The native germplasm pool in Greek populations could be utilized in walnut breeding programmes and germplasm management activities to maximize genetic diversity in cultivated walnuts (Christopoulos et al., 2010).
The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2024.
No available data.
The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2024.
Genetic Characterisation of Juglans regia and its GCUs
Availability of FRM
FOREMATIS
Conifers Network: Report of the fourth meeting
Noble Hardwoods Network: Report of the sixth and seventh meeting
Noble Hardwoods Network: Report of the first meeting
Contacts of experts
NA
Further reading
Bernard, A., Barreneche, T., Lheureux, F., and Dirlewanger, E. 2018. Analysis of genetic diversity and structure in a worldwide walnut (Juglans regia L.) germplasm using SSR markers. PLOS ONE, 13(11): 0208021. https://doi.org/10.1371/journal.pone.0208021
References
Aradhya, M., Velasco, D., Ibrahimov, Z., Toktoraliev, B., Maghradze, D., Musayev, M., Bobokashvili, Z., and Preece, J.E. 2017. Genetic and ecological insights into glacial refugia of walnut (Juglans regia L.). PLOS ONE, 12(10): 0185974. https://doi.org/10.1371/journal.pone.0185974
Bernard, A., Barreneche, T., Donkpegan, A., Lheureux, F., and Dirlewanger, E. 2020. Comparison of structure analyses and core collections for the management of walnut genetic resources. Tree Genetics & Genomes, 16: 76. https://doi.org/10.1007/s11295-020-01469-5
Christopoulos, M.V., Rouskas, D., Tsantili, E., and Bebeli, P.J. 2010. Germplasm diversity and genetic relationships among walnut (Juglans regia L.) cultivars and Greek local selections revealed by inter-simple sequence repeat (ISSR) markers. Scientia Horticulturae, 125(4): 584–592.
Ebrahimi, A., Fatahi, R., and Zamani, Z. 2011. Analysis of genetic diversity among some Persian walnut genotypes (Juglans regia L.) using morphological traits and SSRS markers. Scientia Horticulturae, 130(1): 146–151.
Shanjani, P.S., Dadmand, M., Seyedian, S.E., Rasoulzadeh, L., Hoseini, L.F., Yeganeh, M.R., Amirkhani, M., and Pahlevani, M.R. 2021. Investigation of genetic diversity of Juglans regia using quantitative and qualitative growth traits, Journal of Forest and Wood Products, 74(2): 209–221. doi: 10.22059/jfwp.2021.312071.1134
Tabasi, M., Sheidai, M., Hassani, D., and Koohdar, F. 2020. DNA fingerprinting and genetic diversity analysis with SCoT markers of Persian walnut populations (Juglans regia L.) in Iran. Genetic Resources and Crop Evolution, 67(6): 1437–1447.
Yildiz, E., Pinar, H., Uzun, A., Yaman, M., Sumbul, A., and Ercisli, S. 2020. Identification of genetic diversity among Juglans regia L. genotypes using molecular, morphological, and fatty acid data. Genetic Resources and Crop Evolution, 68(4): 1425–1437.
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