BackgroundThe advent of high-throughput genotyping technologies coupled to genomic prediction methods established a new paradigm to integrate genomics and breeding. We carried out whole-genome prediction and contrasted it to a genome-wide association study (GWAS) for growth traits in breeding populations of Eucalyptus benthamii (n =505) and Eucalyptus pellita (n =732). Both species are of increasing commercial interest for the development of germplasm adapted to environmental stresses.ResultsPredictive ability reached 0.16 in E. benthamii and 0.44 in E. pellita for diameter growth. Predictive abilities using either Genomic BLUP or different Bayesian methods were similar, suggesting that growth adequately fits the infinitesimal model. Genomic prediction models using ~5000–10,000 SNPs provided predictive abilities equivalent to using all 13,787 and 19,506 SNPs genotyped in the E. benthamii and E. pellita populations, respectively. No difference was detected in predictive ability when different sets of SNPs were utilized, based on position (equidistantly genome-wide, inside genes, linkage disequilibrium pruned or on single chromosomes), as long as the total number of SNPs used was above ~5000. Predictive abilities obtained by removing relatedness between training and validation sets fell near zero for E. benthamii and were halved for E. pellita. These results corroborate the current view that relatedness is the main driver of genomic prediction, although some short-range historical linkage disequilibrium (LD) was likely captured for E. pellita. A GWAS identified only one significant association for volume growth in E. pellita, illustrating the fact that while genome-wide regression is able to account for large proportions of the heritability, very little or none of it is captured into significant associations using GWAS in breeding populations of the size evaluated in this study.ConclusionsThis study provides further experimental data supporting positive prospects of using genome-wide data to capture large proportions of trait heritability and predict growth traits in trees with accuracies equal or better than those attainable by phenotypic selection. Additionally, our results document the superiority of the whole-genome regression approach in accounting for large proportions of the heritability of complex traits such as growth in contrast to the limited value of the local GWAS approach toward breeding applications in forest trees.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-017-3920-2) contains supplementary material, which is available to authorized users.

The aim of this study was to evaluate Eucalyptus badjensis concerning the genetic variation for growth traits and the potential of the species in supporting a breeding programme. The field trial was a provenance/progeny test established in Campina da Alegria, Santa Catarina, Brazil (latitude 26°52′05.1″ S, longitude 51°48′47.5″ W, altitude 1,015 m) in a soil classified as Latossolic Alumino-Ferric Brown Nitosol. The experiment comprised 60 open-pollinated progenies from the provenances Glenbog and Badja State Forest, New South Wales, Australia. Ten replicates and plots with six plants in row were used. At the age of 17 years, 279 trees were assessed for diameter of the bole at breast height (DBH), total tree height (H) and volume of wood with bark (Vol). After submitting the data to statistical genetic analysis, the overall means for DBH, H and Vol were 45.17 cm, 33.30 m and 2.84 m3, and the estimates of additive coefficient of variation [CV^a(%)] were 12.59%, 5.91% and 26.51%, respectively. Heritability coefficients of additive effects (trueh^a2) were also estimated and the following values were found: 0.443, 0.312 and 0.358. Thirty-nine trees from 25 different progenies were selected. The expected means of the provenances after improvement were 50.02 cm, 34.35 m and 3.47 m3 for DBH, H and Vol, respectively.

Resumo -As propriedades da madeira de teca (Tectona grandis L. f) regem um intenso processo de domesticação e cultivo em regiões além de seu habitat natural. O interesse na espécie como alternativa aos plantios florestais tradicionais no Brasil vem crescendo. Esta revisão contribui com o processo de resgate da informação técnicocientífica sobre a teca com vistas à elaboração de um programa de melhoramento. Neste documento, é apresentada uma breve revisão sobre os métodos silviculturais para a espécie no Brasil. Foram explorados aspectos positivos inerentes ao cultivo assim como os principais riscos. De forma geral, verificou-se que os programas recentes de melhoramento genético concentraram-se no desenvolvimento de clones. A ênfase inicial dos programas de melhoramento tem sido a taxa de crescimento e propriedades da madeira (geralmente densidade). Para a aplicação e escolha dos métodos de seleção em teca são importantes as variâncias genéticas aditivas e não aditivas, as herdabilidades no sentido restrito e amplo, e as correlações genéticas entre caracteres. Como em outros programas de melhoramento florestal, é comum a conversão de testes de progênies em pomares de sementes para a produção mais rápida de clones comerciais ou de pomares clonais de sementes.Termos para indexação: Brasil, espécies exóticas, Tectona grandis, programa de melhoramente. Overview of the teak silviculture in Brazil and perspectives for genetic improvementAbstract -The teak (Tectona grandis L. f.) wood properties direct an intense process of domestication and plantation outside its original habitat. The interest in the species as an alternative for the traditional forest plantations in Brazil is growing. This review contributes with the recovery of technical and scientific information regarding teak aiming the subsequent proposition of a genetic breeding program. In this paper it is presented a brief review of the silvicultural methods for the species in Brazil. The positive perspectives and the main risks related to the teak plantation were explored. In general, in the most recent genetic improvement programs the employment of clones was a common strategy. The initial emphasis of the improvement programs were the growth rate and wood property (generally density). As for other species the proper choice of the selection methods resides in observing the genetic variances (additive and non-additive), herdability (broad and narrow), and the genetic correlations among characters. As in other forest breeding programs the conversion of progeny tests in seedling seed orchards is common for a faster seed production and development of commercial clones or clonal seed orchards.

Resumo-Com objetivo de avaliar o desempenho de clones comerciais de eucalipto na região de Ponta Porã, MS, foram instalados dois testes clonais de eucalipto em 2009. Cada experimento foi composto por cinco clones (AEC 144, AEC 224, GG 100, 58 e COP 1277) e três testemunhas seminais (Eucalyptus grandis, Eucalyptus urophylla e Eucalyptus urophylla x Eucalyptus grandis). Os experimentos foram instalados em blocos casualizados, com quatro repetições, parcelas quadradas de 25 plantas (Ensaio 1) e 16 plantas (Ensaio 2), em espaçamento de 3 m x 3 m. Aos 51 meses foram mensuradas: circunferência à altura do peito e altura. A partir dessas informações foi estimado o volume de madeira por árvore. Realizou-se também avaliação fenotípica com base em características silviculturais. Os clones AEC 144 e AEC 224 apresentaram as maiores estimativas de volume de madeira. O uso desses clones em plantios comerciais deve proporcionar bons níveis de produtividade, desde que aplicadas adequadas técnicas silviculturais.

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