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Großhansdorf, Germany

Holtken A.M.,University of Hamburg | Holtken A.M.,Plant Genetic Diagnostics GmbH | Buschbom J.,Johann Heinrich Von Thunen Institute | Katzel R.,Landeskompetenzzentrum Forst Eberswalde LFE
Allgemeine Forst- und Jagdzeitung

Species integrities are under question for pedunculate, sessile and downy oak since years due to their hybridization ability. The present study clearly shows a limited impact of hybridization on the gene pools of the three oak species and the genetic distinctiveness of the species. Its results are based on analyses of eight markers (nuclear microsatellite loci) in two and more stands of each oak species (table 1). Genetic diversity and structure within and between the three morphologically identified species were described using genetic profiles [figure 1) and summarized using indices of genetic diversity and differentiation (tables 2, 3 and 4). In addition, the gene pool of the three species represented by the present population and species sample was partitioned into reproductive units independently of a priori assumptions using the model-based approach implemented in the program STRUCTURE 2.3.2 {figure 2, table 5). Our results support the following conclusions: the program STRUCTURE allows not only a clustering of species within oaks, but also resolves intraspecific population structure. Population structure is less visible in the common and widespread species Q. robur and Q. petraea in comparison to the rare and scattered Q. pubescens. Downy oak is restricted to extrazonal habitats in Central Europe and, thus, genetic drift will have a larger impact. In sum, the employed gene marker set provides a reliable and decisive basis for the partitioning of stands and single individuals to species and reproductive units, respectively. The present approach can be used for the identification of hybrids and their admixture proportions, the study of stand histories and the selection of valuable gene resources, especially regarding scattered downy oak stands in Central Europe. Source

Degen B.,Johann Heinrich Von Thunen Institute | Holtken A.,Plant Genetic Diagnostics GmbH | Rogge M.,Landesbetrieb Wald und Holz Nordrhein Westfalen
Silvae Genetica

Well-adapted, high quality reproductive material is key to the success of forest plantations. Consequently in many countries the collection and trade of forest reproductive material is regulated. Paper documents are usu-ally the only evidence for the origin of forest reproductive material. Certification schemes already established in Germany use genetic inventories to compare reference samples collected at different steps of the chain-ofcustody. A new approach using DNA-fingerprints efficiently controls the origin of seed sources without these multiple reference samples. Only a sample of adult trees within the seed stands is needed. The control is directly made for each suspicious plant or a group of suspicious plants by use of multilocus genotype assignment. We made a field test with samples of adults and seedling from 5 registered seed stands of Quercus robur in Western Germany. Eight highly variable nuclear microsatellites were used to genotype each individual. We found in total 255 different alleles at all loci in the adult populations. The observed levels of genetic variation (A e= 9.18), genetic differentiation (delta = 0.187) and population fixation (F ST = 0.01) were slightly higher than results of similar studies. Individual and group assignment tests were performed with the Bayesian multi-locus approach. The proportion of correctly assigned seedlings was 65% for individuals with completely scored genotypes. In all 5 cases the groups of seedlings were assigned to the correct seed stand and an additional sample of seedlings from another stand could be successfully excluded with a probability test. The conclusion of the field study is that a large scale application of this new approach to control of the origin of forest reproductive material is feasible. Source

Katzel R.,Landeskompetenzzentrum Forst Eberswalde | Kamp T.,Forstburo Ostbayern | Holtken A.M.,Plant Genetic Diagnostics GmbH | Becker F.,Landeskompetenzzentrum Forst Eberswalde | And 2 more authors.
Landbauforschung Volkenrode

Pubescent oak (Quercus pubescens Willd.) is a rare tree species in Germany. Its populations here mark the northern border of its natural range in Europe. A nationwide inventory of all Q. pubescens populations was carried out from 2010 to 2013 following standardised methods and criteria. 26 spatially separate occurrences with a total of 14,500 individuals of all ages could be identified. Population areas range from 0.5 to 38 ha with a median of 2.6 ha. Analyses included a population in the Polish nature reserve "Bieliniek" in the Oder river valley. Regarding age structure, vitality, and abundance, the regions with the highest in-situ "maintainability" are located in the Southwest of Baden-Wuerttemberg. Populations in other regions could either not be found or consisted of hybrids and other Quercus species. DNA markers were applied in most of the populations in order to assess their taxonomic status and genetic diversity. Diverging values of genetic diversity and high genetic differentiation compared to populations of Q.petraea and Q. rofaur indicate that genetic drift has strongly affected genetic structures due to reproductive isolation and small effective population sizes. As a result of genotype-based clustering methods, only three German and the Polish population in Bielinek proved to be pure while two other stands were classified as almost pure Q. pubescens. All other analyzed populations turned out to include considerable numbers of hybrids and/or Sessile oak. Source

Reim S.,Julius Kuhn Institute | Holtken A.,TU Hamburg - Harburg | Holtken A.,Plant Genetic Diagnostics GmbH | Hofer M.,Julius Kuhn Institute
Genetic Resources and Crop Evolution

In the present study genetic diversity and hybridization with cultivars were investigated in a population of the endangered European wild apple species Malus sylvestris (L.) Mill. with the aim to establish a basis for the implementation of conservation activities and to ensure its long-term preservation. A total of 284 putative M. sylvestris trees located in the East Ore Mountains were investigated along with a standard set of reference apple genotypes proposed by the European Cooperative Program for Plant Genetic Resources (ECPGR) and 13 old apple cultivars often cultivated in Saxony. The genetic analysis was performed using 12 microsatellite markers also recommend by the ECPGR. To differentiate 'true type' M. sylvestris individuals, hybrids and apple cultivars (Malus × domestica Borkh.) a model-based cluster analysis was performed using STRUCTURE. Two clusters were identified consisting of M. sylvestris and M. × domestica genotypes. About 40 % of the putative M. sylvestris showed an admixture of the species-specific allele frequencies and were defined as hybrids. The genetic diversity of the 'true type' M. sylvestris population was still high but slightly lower than in the apple cultivars especially since some SSR loci were fixed on one or few alleles in the M. sylvestris population. The differentiation parameters between 'true type' wild apple and cultivars indicated a clear discrimination between the wild and cultivated apple individuals. This fact confirms our expectation of the existence of 'true type' M. sylvestris individuals in the East Ore Mountains and argues for the realization of preservation measures in this area. © 2012 Springer Science+Business Media Dordrecht. Source

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