Browsing by Author "Kremer, Antoine"
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- Comparison of genetic diversity estimates within and among populations of maritime pine using chloroplast simple-sequence repeat and amplified fragmentPublication . Ribeiro, M.M.A.; Mariette, Stéphanie; Vendramin, Giovanni Giuseppe; Szmidt, A.E.; Plomion, Christophe; Kremer, AntoineWe compared the genetic variation of Pinus pinaster populations using amplified fragment length polymorphism (AFLP) and chloroplast simple-sequence repeat (cpSSR) loci. Populations’ levels of diversity within groups were found to be similar with AFLPs, but not with cpSSRs. The high interlocus variance associated with the AFLP loci could account for the lack of differences in the former. Although AFLPs revealed much lower genetic diversity than cpSSRs, the levels of among-population differentiation found with the two types of marker were similar, provided that loci showing fewer than four null-homozygotes, in any population, were pruned from the AFLP data. Moreover, the French and Portuguese populations were clearly differentiated from each other, with both markers. The Mantel test showed that the genetic distance matrix calculated using the AFLP data was correlated with the matrix derived from the cpSSRs. Because of the concordance found between markers we conclude that gene flow was indeed the predominant force shaping nuclear and chloroplastic genetic variation of the populations within regions, at the geographical scale studied.
- Genetic resources in maritime pine (Pinus pinaster Aiton):molecular and quantitative measures of genetic variation and differentiation among maternal lineagesPublication . González Martínez, Santiago; Mariette, Stéphanie; Ribeiro, M.M.A.; Burban, Christian; Raffin, Annie; Chambel, Regina; Ribeiro, Carla Alexandra; Aguiar, Alexandre; Plomion, Christophe; Alía, Ricardo; Gil, Luis; Vendramin, Giovanni Giuseppe; Kremer, AntoinePinus pinaster is a conifer native to western Europe and northern Africa. Following on-going breeding programmes, provenance and progeny trials were established in some of the countries of the species’ range (France, Portugal and Spain) and quantitative traits were measured: growth, stem form, survival and pest and disease resistance, amongst others. Populations from the wide range of P. pinaster were recently screened with molecular markers in order to assess their genetic diversity. Data were obtained using allozymes, chloroplast (cpSSRs) and nuclear (nuSSRs) microsatellites and amplified fragment length polymorphisms (AFLPs). Based on mtDNA-RFLP analysis, three maternal lineages (named ‘‘western’’, ‘‘eastern’’ and ‘‘Moroccan’’) were identified and no population showed a mixed composition. In this study, the imprint that differentiation in putatively isolated glacial refugia (identified by the different maternal lineages) might have left on the nuclear genome was analysed using a wide range of molecular markers and adaptive traits. Multivariate ordination of populations based on nuclear molecular markers (allozymes and nuSSRs) showed a clear clustering of provenances sharing a given mtDNA lineage. However, that clustering was found to be less tight when only quantitative traits were investigated. In P. pinaster, the within-population estimates of gene diversity using different traits were not correlated. Therefore, caution is advisable when designing conservation strategies based on molecular marker studies or a limited number of populations. After these results, we recommend a conservation strategy characterised by gene flow consistent with the current population structure, careful seed transfer among maternal lineages (if any), selection of populations for conservation based on the originality of their allelic composition and definition of Management Units (MUs) based on adaptive traits..