Keystone species in their native ranges, eucalypts, are ecologically and genetically very diverse, growing naturally along extensive latitudinal and altitudinal ranges and variable environments. Besides their ecological importance, eucalypts are also the most widely planted trees for sustainable forestry in the world. We report the development of a novel collection of 535 microsatellites for species of Eucalyptus, 494 designed from ESTs and 41 from genomic libraries. A selected subset of 223 was evaluated for individual identification, parentage testing, and ancestral information content in the two most extensively studied species, Eucalyptus grandis and Eucalyptus globulus. Microsatellites showed high transferability and overlapping allele size range, suggesting they have arisen still in their common ancestor and confirming the extensive genome conservation between these two species. A consensus linkage map with 437 microsatellites, the most comprehensive microsatellite-only genetic map for Eucalyptus, was built by assembling segregation data from three mapping populations and anchored to the Eucalyptus genome. An overall colinearity between recombination-based and physical positioning of 84% of the mapped microsatellites was observed, with some ordering discrepancies and sporadic locus duplications, consistent with the recently described whole genome duplication events in Eucalyptus. The linkage map covered 95.2% of the 605.8-Mbp assembled genome sequence, placing one microsatellite every 1.55 Mbp on average, and an overall estimate of physical to recombination distance of 618 kbp/cM. The genetic parameters estimates together with linkage and physical position data for this large set of microsatellites should assist marker choice for genome-wide population genetics and comparative mapping in Eucalyptus.
Eucalypts are the world's most widely planted hardwood trees. Their outstanding diversity, adaptability and growth have made them a global renewable resource of fibre and energy. We sequenced and assembled >94% of the 640-megabase genome of Eucalyptus grandis. Of 36,376 predicted protein-coding genes, 34% occur in tandem duplications, the largest proportion thus far in plant genomes. Eucalyptus also shows the highest diversity of genes for specialized metabolites such as terpenes that act as chemical defence and provide unique pharmaceutical oils. Genome sequencing of the E. grandis sister species E. globulus and a set of inbred E. grandis tree genomes reveals dynamic genome evolution and hotspots of inbreeding depression. The E. grandis genome is the first reference for the eudicot order Myrtales and is placed here sister to the eurosids. This resource expands our understanding of the unique biology of large woody perennials and provides a powerful tool to accelerate comparative biology, breeding and biotechnology.
Pulp revascularization may be considered a promising alternative for traumatized necrotic immature teeth. The aim of this study was to evaluate traumatized immature teeth treated with 2 protocols of pulp revascularization.
Fine mapping of quantitative trait loci (QTL) from previous linkage studies was performed on pig chromosomes 1, 4, 7, 8, 17, and X which were known to harbor QTL. Traits were divided into: growth performance, carcass, internal organs, cut yields, and meat quality. Fifty families were used of a F2 population produced by crossing local Brazilian Piau boars with commercial sows. The linkage map consisted of 237 SNP and 37 microsatellite markers covering 866 centimorgans. QTL were identified by regression interval mapping using GridQTL. Individual marker effects were estimated by Bayesian LASSO regression using R. In total, 32 QTL affecting the evaluated traits were detected along the chromosomes studied. Seven of the QTL were known from previous studies using our F2 population, and 25 novel QTL resulted from the increased marker coverage. Six of the seven QTL that were significant at the 5% genome-wide level had SNPs within their confidence interval whose effects were among the 5% largest effects. The combined use of microsatellites along with SNP markers increased the saturation of the genome map and led to smaller confidence intervals of the QTL. The results showed that the tested models yield similar improvements in QTL mapping accuracy.
High-throughput SNP genotyping has become an essential requirement for molecular breeding and population genomics studies in plant species. Large scale SNP developments have been reported for several mainstream crops. A growing interest now exists to expand the speed and resolution of genetic analysis to outbred species with highly heterozygous genomes. When nucleotide diversity is high, a refined diagnosis of the target SNP sequence context is needed to convert queried SNPs into high-quality genotypes using the Golden Gate Genotyping Technology (GGGT). This issue becomes exacerbated when attempting to transfer SNPs across species, a scarcely explored topic in plants, and likely to become significant for population genomics and inter specific breeding applications in less domesticated and less funded plant genera.
The first registers of Somali sheep in Brazil are from the beginning of the 1900s. This breed, adapted to the dry climate and scarce food supply, is restricted in the northeast region of the country. Molecular marker technologies, especially those based on genotyping microsatellite and mtDNA loci, can be used in conjunction with breeding (pedigree analysis) and consequently the maintenance of genetic variation in herds. Animals from the Brazilian Somali Conservation Nuclei from Embrapa Sheep and Goats in Ceará State were used to validate genetic monitoring by traditional pedigree methods and molecular markers. Nineteen microsatellite markers and 404 base pairs from the control region of mtDNA were used. For total herd diversity, an average 5.32 alleles were found, with expected heterozygosity of 0.5896, observed heterozygosity of 0.6451, 0.4126 for molecular coancestrality, and coefficient of inbreeding (F (IS)) was -0.095. Comparing molecular coancestrality means over the years, there was a consistent increase in this parameter within the herd, increasing from 0.4157 to 0.4769 in 2 years (approx. 12% variation). Sixteen mtDNA haplotypes were identified. Inbreeding and other estimates from genealogical analyses confirm the results from molecular markers. From these results, it is possible to state that microsatellites are useful tools in genetic management of herds, especially when routine herd recording is not carried out, or there were gaps in recent generations. As well as pedigree control, genetic diversity can be optimized. Based on the results, and despite herd recording in the herd of Brazilian Somali of Embrapa Sheep and Goats, additional management measures need to be carried out in this herd to reduce inbreeding and optimize genetic variation.
Species of Eucalyptus are keystone species for ecological studies in their natural ranges and are extensively planted in the tropical and subtropical regions of the world to supply high-quality woody biomass for various applications. We report the development of a selected set of 20 dinucleotide and trinucleotide repeat microsatellites derived from Eucalyptus expressed sequence tags (ESTs). These microsatellites were selected for full transferability and homogeneous rate of polymorphism across species. They were evaluated for individual fingerprinting, parentage testing, and intraspecific population structure analyses in 6 of the most extensively studied and planted species worldwide, representing key phylogenetic sections of the largest subgenus Symphyomyrtus. This set of markers provides exceptional resolution for population genetics and molecular breeding applications in the genus Eucalyptus. As they were developed from conserved transcribed regions, the transferability and polymorphism of these microsatellites will most likely extend to the other 300 or more species within the same subgenus.
• Genomic selection (GS) is expected to cause a paradigm shift in tree breeding by improving its speed and efficiency. By fitting all the genome-wide markers concurrently, GS can capture most of the missing heritability of complex traits that quantitative trait locus (QTL) and association mapping classically fail to explain. Experimental support of GS is now required. • The effectiveness of GS was assessed in two unrelated Eucalyptus breeding populations with contrasting effective population sizes (N(e) = 11 and 51) genotyped with > 3000 DArT markers. Prediction models were developed for tree circumference and height growth, wood specific gravity and pulp yield using random regression best linear unbiased predictor (BLUP). • Accuracies of GS varied between 0.55 and 0.88, matching the accuracies achieved by conventional phenotypic selection. Substantial proportions (74-97%) of trait heritability were captured by fitting all genome-wide markers simultaneously. Genomic regions explaining trait variation largely coincided between populations, although GS models predicted poorly across populations, likely as a result of variable patterns of linkage disequilibrium, inconsistent allelic effects and genotype × environment interaction. • GS brings a new perspective to the understanding of quantitative trait variation in forest trees and provides a revolutionary tool for applied tree improvement. Nevertheless population-specific predictive models will likely drive the initial applications of GS in forest tree breeding.
Related JoVE Video
Journal of Visualized Experiments
What is Visualize?
JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.
How does it work?
We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.
Video X seems to be unrelated to Abstract Y...
In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.