Genetic monitoring of traditional chestnut orchards reveals a complex genetic structure M.A. Martín, E. Monedero, L.M. Martín To cite this version: M.A. Martín, E. Monedero, L.M. Martín. Genetic monitoring of traditional chestnut orchards reveals a complex genetic structure. Annals of Forest Science, Springer Nature (since 2011)/EDP Science (until 2010), 2017, 74 (1), pp.15. 10.1007/s13595-016-0610-1. hal-01710360 HAL Id: hal-01710360 https://hal.archives-ouvertes.fr/hal-01710360 Submitted on 15 Feb 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Annals of Forest Science (2017) 74: 15 DOI 10.1007/s13595-016-0610-1 ORIGINAL PAPER Genetic monitoring of traditional chestnut orchards reveals a complex genetic structure M.A. Martín1 & E. Monedero2 & L.M. Martín2 Received: 7 June 2016 /Accepted: 14 December 2016 /Published online: 15 February 2017 # INRA and Springer-Verlag France 2017 Abstract characteristics, man influenced its populations (grafting/sexu- & Key message This study presents the results of a system- al propagation) and a complex genetic structure is expected. atic genetic analysis between wild and cultivated chestnuts & Aims We monitored the trees of a chestnut orchard for study- in an orchard in southern Spain, highlighting a complex ing the genetic diversity and relationship in grafts and root- structure and considerable genetic diversity and opening stocks and detecting possible response in its adaptive the possibility to generalize this approach to other potential. Mediterranean orchards. & Methods For this, morphological traits and genomic and & Context Tree genetic monitoring offers a good opportunity genic microsatellite markers were used. to evaluate populations and preserve their long-term adaptive & Results Chestnut trees showed considerable genetic struc- evolutionary potential. Chestnut is a multipurpose species of ture, with high level of clonality in the varieties and genetic high economic importance in the Mediterranean basin and diversity in rootstocks. The similarity analysis revealed a dif- considered an example of integration between natural and ferent clustering pattern for varieties, detecting higher vari- man-driven distribution of diversity under changing environ- ability for genomic microsatellite markers. Rootstocks mental and historical conditions. Due to its multipurpose harboured a high level of diversity, not previously described, and not contained in the genetic information from populations and varieties from the same region. Handling Editor: Bruno Fady & Conclusion Results contribute to understanding the human Contribution of the co-authors M. Angela Martín participated in the role in the management of chestnut and demonstrate that root- design of the experiment, ran the data analysis, led the discussion and stocks constitute an unexploited reservoir of variation valu- wrote the paper. Elvira Monedero participated in the collection of data in the field and conducted the laboratory analyses. Luis Miguel Martín able for conservation strategies against stress factors and fu- designed the experiment, conducted the collection of data in the field, ture and unpredictable environmental changes. supervised the work and coordinated the research project. Electronic supplementary material The online version of this article Keywords Castanea sativa . Genetic resources . On farm (doi:10.1007/s13595-016-0610-1) contains supplementary material, conservation . Clonality . Rootstocks which is available to authorized users. * M.A. Martín [email protected] 1 Introduction Genetic monitoring offers a good opportunity for evaluating 1 Departamento de Ingeniería del Medio Agronómico y Forestal, the status of tree population genetic resources over time, pre- Avda. Virgen del Puerto No. 2, Centro Universitario de Plasencia, Universidad de Extremadura, ES-10600 Plasencia, Spain serving their long-term adaptive evolutionary potential and detecting possible critical signals that demand management 2 Departamento de Genética, E.T.S.I.A.M, Edificio Gregor Mendel, Campus de Rabanales, Campus de Excelencia Internacional action (Schwatz et al. 2006; Graudal et al. 2014). This implies Agroalimentario (ceiA3), Universidad de Córdoba, a systematic survey of the amount of genetic variation, genetic ES-14071 Córdoba, Spain composition and spatial genetic structure to detect potential 15 Page 2 of 11 Annals of Forest Science (2017) 74: 15 changes in these parameters that may result in loss of gene- between chestnut cultivars and their origin areas and level variability (Laikre et al. 2008). also by the high diversity of different clonally propagat- Tree genetic resources exist at different levels of do- ed cultivars found in all countries where chestnut is mestication, and the landscapes within which they are traditionally grown (Gobbin et al. 2007; Martín et al. located are themselves domesticated to a greater or less- 2009, 2010; Pereira-Lorenzo et al. 2010). er extent (Michon 2005). In this respect, traditional Nevertheless, in the last decades, there has been a strong agroecosystems involve the integration of trees with decline in chestnut cultivation closely associated with ink dis- crops and livestock production and exhibit common fea- ease caused by Phytophthora cinnamomi Rands. This tures such as a high diversity of species, the use of oomycete infects the root system, causing the wilting and diversified traditional varieties and low inputs associated death of chestnut trees (Crandall et al. 1945). Its impact on with traditional farming practises (Garrity 2004). In the production has dramatic consequences in local economies these systems, on farm conservation is practised to pre- that discourage farmers to continue growing chestnut. In some serve landraces in areas in which they were originally parts in Europe, the impact of P. cinnamomi has been mitigat- cultivated and with traditional technologies that have ed by the use of rootstocks that come from the hybridization been practised by farmers for millennia (Maxted et al. between C. sativa and two Asian tolerant species (Castanea 1997). Nevertheless, this conservation will only be ef- crenata and Castanea mollissima) (Fernández-López et al. fectiveifitispossibletoassessthegeneticdiversity 2001). However, these hybrids displayed some problems as conserved in these agroecosystems and how they can graft incompatibility reactions between rootstock and cultivar, evolve (Graudal et al. 2014). different agronomic traits not accepted by growers and/or con- The Mediterranean basin still harbours traditional sumers and poor adaptation to climatic conditions. In particu- agroecosystems of particular importance for preserving biodi- lar, in southern Europe, the use of these hybrids has proved to versity, and sweet chestnut (Castanea sativa Miller) is a good be unsuitable due to difficulties of adaptation of this resistant example. This multipurpose species of high economic impor- material to southern latitudes. For this reason, local rootstocks tance is valued not only for fruit and timber production but from C. sativa, developed by growers in different also for its contribution to the landscape and environment. It is edaphoclimatic regions from central and southern Spain, are accepted that domestication events in chestnut started several usually the ones which are best adapted to the warmer and millennia ago and were characterized by clonal propagation drier local conditions and to the traditional varieties (Pereira- and selection of the best genotypes that resulted in a popula- Lorenzo et al. 2010; Dinis et al. 2011). tion structure far from what would be expected in a purely Genetic variation in orchards and naturalized populations natural situation. Thus, chestnut genetic structure is complex has been evaluated separately (Martín et al. 2012; Mattioni and depends on the type of management: orchards (dedicated et al. 2013); thus, there are no genetic data on their possible to fruit production), coppices (dedicated to timber production) relationship. Furthermore, the role of rootstocks in this genetic and naturalized populations (Grossmann and Romane 2004). diversity has not been addressed in any study. It has been In particular, orchards are constituted by trees of advanced and speculated that the genetic structure contained in rootstocks heterogeneous age, and chestnut cultivation involves grafting could be similar to that contained in the varieties or in the of traditional cultivars onto rootstocks. Thus, the trees from a populations although there are no empirical data that support given variety are clones, whereas rootstocks are the result of this hypothesis. the germination of nuts selected by growers for its superior Molecular markers provide valuable information about the traits from different chestnut varieties or from wild popula- genetic status and biological processes of populations, making tions (Martín et al. 2009; Marinoni et al. 2013). genetic monitoring increasingly feasible and cost-effective Furthermore, trees can show one or more varieties in the aerial