Selection of a seed orchard of Eucalyptus dunnii based on genetic diversity criteria calculated using molecular markers

Abstract

A Eucalyptus dunnii Maiden breeding population of 46 accessions originated in Australia and selected for fitness to subtropical and cold environments was screened by Amplified Fragment Length Polymorphism (AFLP) and microsatellite markers to obtain quantitative estimates of genetic diversity. A randomly chosen group of AFLP primers generated 205 AFLP bands that were used to fingerprint the genotypes and to evaluate genetic relationships among accessions. Sixty-eight percent (140) of the bands were polymorphic markers. The mean diversity index (DI) was 0.33 and about 52% of the loci had values greater than 0.4. Cluster analysis derived from similarity indices (SI) revealed no particular grouping among accessions suggesting the absence of closely related genotypes, except for five pairs of genotypes. Bootstrap analysis results confirmed the suitability of AFLP to describe genetic relationships in this breeding population. In addition, four highly informative microsatellites were used to construct an identification matrix that discriminated nearly all of the genotypes. Mean values for the number of alleles per locus, DI and SI among accessions were 13, 0.78 and 0.19, respectively, indicating that the breeding population has high genetic diversity. However, several genotypes showed the presence of single microsatellite bands suggesting a putatively important degree of homozygosity. Molecular data were used to design a clonal seed orchard. To achieve this aim, the nine most divergent pairs of genotypes were chosen, thereby retaining 95.2% of the total number of alleles from the 140 polymorphic AFLP loci and the four microsatellite loci analyzed. Mean DI and SI for AFLP and microsatellites showed no significant differences between the original breeding population and the selected seed orchard, confirming that a seed orchard can be designed with a limited number of individuals, which allows similar accessions to be discarded and avoids inbreeding.

Population genetic analysis and phylogeny reconstruction in Eucalyptus (Myrtaceae) using high-throughput, genome-wide genotyping

“…Bussell et al (2005) recommended AAD markers for phylogenetic and systematic studies of closely related species and non-reticulating, subspecific lineages, since below these taxonomic levels, population genetic effects (reticulation) may swamp hierarchical signal in the data, while at higher taxonomic levels homoplasy is likely to be significant. AAD markers have been used to examine genetic structure within and between populations of individual species of Eucalyptus (e.g., RAPD -Nesbitt et al 1995;Gaiotto et al 1997, Li 2000ISSR -Okun et al 2008;AFLP -Gaiotto et al 1997, Poltri et al 2003 but also to examine relationships among closely related (reticulating) species. In accordance with the findings of Bussell et al (2005), McKinnon et al (2008) could not separate closely related species within sect.…”

Caracterização da capacidade fotossintética e da condutância estomática em sete clones comerciais de Eucalyptus e seus padrões de resposta ao déficit de pressão de vapor

“…O conhecimento da diversidade genética é importante tanto para estratégias de planejamento de clonagem como também para fornecer uma base científica para aprimorar o manejo de recursos genéticos em espécies arbóreas florestais (POLTRI et al, 2003). A variabilidade genética forma a base para mudanças fenotípicas dentro da seleção, seja ela natural ou artificial, através de programas de melhoramento (EMHART et al, 2007).…”

“…Estes resultados confirmam a relação entre A e g s , já demonstrada por vários autores (GRANTZ, 1990;DAI et al, 1992), destacando a alta sensibilidade destes clones comerciais de alta produção às condições de estresse hídrico (GUEHL; AUSSENAC, 1987;PATHRE, 2004 Há uma variação de transpiração, entre os clones, de 93% e 170% na primeira e na segunda campanha, respectivamente, evidenciando que com o passar do tempo, os clones foram se tornando mais distintos entre si, à semelhança da fotossíntese e condutância estomática. Assim, uma análise precoce de características ecofisiológicas dos clones pode não ser adequada para avaliar o seu comportamento ao longo de todo o ciclo (INOUE et al, 1998;GINDABA et al, 2004;SUSILUOTO;BERNINGER, 2007;THOMAS et al, 2007 Estes resultados evidenciam a necessidade de se conhecer o comportamento dos distintos materiais frente ao DPV, e verificar se comportamentos como o do clone C são efetivamente consistentes, replicáveis e herdáveis (POLTRI et al, 2003 demonstram uma maior sensibilidade ao DPV (CUNNINGHAM, 2004;OREN et al, 1999 (EMHART et al, 2007).…”

Application of biotechnology for the domestication of Dacryodes edulis (G. Don) H. J. Lam in Cameroon: A review

“…Selecting trees from natural or planted tree populations must have a certain degree of genetic diversity. Genetic diversity is of fundamental importance to the long term survival and evolution of the species and it gives an opportunity to tree breeders to carry out selection from their breeding populations and thus conservation and management of the germplasm (Poltri et al, 2003). Improving all the traits of interest simultaneously due to pleiotropy effect of genes was identified by Leakey and Ladipo (1996) and Tchatchoua et al (2012).…”