Reservoir of the European chestnut diversity in Switzerland

Abstract

In Switzerland, chestnut forests cover about 27100 ha, plus some 6800 ha of mixed stands.Due to environmental and historical reasons, most of these still existing forests are located in the Swiss Southern Alps, whereas in the northern parts of the country the chestnut cultivation and the related knowledge strongly regressed since the Little Ice Age period.Nevertheless, Switzerland still hosts valuable genetic resources of the sweet chestnut tree.The present genetic study bases on a nationwide inventory, identification and precise localisation of old and/or grafted chestnut trees for conservation purposes. The main objectives were 1) to evaluate the genetic diversity and the genetic structure of Castanea sativa Mill. in Switzerland, and 2) to define a program of conservation including the proposal of a defined core collection. We genetically analysed a pre-selection of 962 accessions (out of 14165 inventoried trees throughout Switzerland), profiling them with 24 microsatellites. We identified 675 different genotypes out of 962 accessions with a 29.8% of repetitiveness due to clonality. A structural analysis based on a Bayesian method allowed to identify two main clusters, one mostly related to the genetic group from southern Europe (Reconstructed Panmictic Population RPP1) and a second one (RPP2) which revealed to be independent and genetically different from other European groups of chestnut cultivars. The Swiss RPP2 represents a new genetic group, and consequently a complement to genetic resources of chestnut tree in Europe. Genetic analysis allowed defining a core collection of 46 genotypes, which should be used in priority for the Swiss conservation program.

Genetic Diversity of Castanea sativa Mill. Accessions from the Tuscan-Emilian Apennines and Emilia Romagna Region (Italy)

“…The presence of ancient trees and known varieties in the same cluster had already been described in Italy and Spain [28] and in Switzerland [24].…”

“…Further Marroni groups with the same molecular profile, such as cv. 'Marrone di Cuneo', 'Marrone di Combai' and 'Chiusa Pesio', were also described in Piedmont [8,9,44] and showed a different genetic profile compared to the 'Marrone di Cuneo' (genetic synonym of 'Marrone Gambarogno') found in Switzerland [24].…”

“…The same approach can be used for the analysis of the genetic diversity of chestnuts as well. This approach was used to characterize germplasm collections [8,9,24] and to describe the existing relationships among Italian and European varieties [25][26][27][28][29]. The use of SSRs allowed the identification and characterization of traditional varieties from southern Spain [8,30].…”

“…The use of SSRs allowed the identification and characterization of traditional varieties from southern Spain [8,30]. These studies could be used as a model in order to extend the analysis to other regional germplasms in Italy and Europe [24,27,29], to characterize the collections and to provide tools for varietal certification.…”

The Who or the How? Species vs. Ecosystem Function Priorities in Conservation Ecology

“…One of those species showing a similar decay pattern, and thus a similar potential decrease in energy reduction capacity against rockfall, is Castanea sativa (European chestnut). Ironically, C. sativa was originally also introduced to the area (∼2k years ago; Conedera et al, 2004 ), and now enjoys considerable conservation efforts to protect it ( Pereira-Lorenzo et al, 2020 ). It is an interesting phenomenon how with prolonged exposure, humans seem to legitimatize “naturalized” alien species, sometimes through the association of a historic connotation.…”