Genetic parameters for lignin, extractives and decay in Eucalyptus globulus 01/2006;


Eucalyptus globulus is grown in temperate regions of the world for pulp production. The chemical and physical properties of its wood make it highly suited to this purpose. This study analysed genetic variation in lignin content, extractives content and decay, for nine localities of E. globulus. Heritability estimates were also obtained, and the relationships between these traits and physical wood traits and growth were examined. Significant genetic variation was found between localities for lignin content (Klason lignin and acid-soluble lignin contents) and decay. The only trait for which significant variation between families within locality was detected was acid-soluble lignin content, which resulted in this trait also having the highest narrow-sense heritability ($0.51 \pm 0.26$). However, family means heritabilities were high for lignin content, extractives content and decay (0.42–0.64). The chemical wood traits were strongly correlated with each other both phenotypically and genetically, with important correlations found with density and microfibril angle. Correlations suggested that during selection for the breeding objective traits, it is likely that favourable states in the chemical wood traits, decay resistance and fibre properties are concurrently being selected, whereas growth may be selected for independently. This initial study provides a stepping stone for future studies where particular localities of the breeding population may be characterised further. Paramètres génétiques pour la lignine, les extractibles et la pourriture chez Eucalyptus globulus. Eucalyptus globulus est cultivé dans de nombreuses régions tempérées pour la production de pâte à papier. Les propriétés physiques et chimiques de ce bois en font un matériau très apprécié pour cette utilisation. Cette étude analyse les variations génétiques de la teneur en lignine, en composés extractibles et de la sensibilité à la décomposition du bois de neuf provenances de Eucalyptus globulus. L'héritabilité de ces propriétés ainsi que leurs relations avec les caractéristiques physiques du bois et la croissance ont été examinées. Des différences inter-provenances significatives ont été détectées pour les teneurs en lignine (lignines dosées par la méthode de Klason, ou lignines soluble en solution acide) et la vitesse de décomposition. Le seul caractère qui a présenté une variation significative entre familles dans les provenances a été la teneur en lignines solubles en solution acide. De ce fait, une forte héritabilité (au sens strict) a été détectée pour ce caractère ($0,51 \pm 0,26$). Cependant, les héritabilités moyennes dans les familles étaient élevées pour la teneur en lignine, les teneurs en composés extractibles et la vitesse de décomposition (0,42–0,64). Les caractéristiques chimiques du bois étaient fortement inter-corrélées au niveau phénotypique et génétique, avec des corrélations importantes également avec la densité et l'angle des microfibrilles. Les corrélations suggèrent que durant la sélection de caractères objectifs d'amélioration, des traits favorables associant caractéristiques chimiques du bois, résistance à la décomposition et propriétés des fibres puissent être sélectionnés simultanément, alors que la croissance doit faire l'objet d'une sélection indépendante. Cette étude constitue une base pour de futurs travaux permettant une caractérisation plus fine de provenances particulières dans cette population de sélection.

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Available from: Carolyn A Raymond, Feb 22, 2015
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    • "), although different from other studies (Stackpole et al. 2011; Apiolaza et al. 2005). Water extractive and ethanol extractive presented contrasted heritabilities, h 2 =0.54 and h 2 =0.28, respectively, and high genetic correlation in accordance with previous Eucalyptus studies (Poke et al. 2006; Bush et al. 2011). Alpha cellulose and hemi-cellulose also presented contrasted heritabilities (h 2 =0.21 and h 2 =0.67, respectively ) and were moderately correlated (ρ A = 0.46). "
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    ABSTRACT: We developed a quantitative and association genetic study with Eucalyptus urophylla using a progeny trial. Based on a sample of 831 trees distributed in 84 half-sib families whose wood was phenotyped by near-infrared spectroscopy, the results showed that traits related to lignin, cellulose, and wood extractives presented significant additive genetic variability with moderate to high narrow sense heritability (h 2 = 0.28 to 0.93). Genetic correlations varied with high standard error and showed low to moderate values. Using three cellulose synthase genes (EuCesA1, EuCesA2, and EuCesA3) and three candidate genes involved in the lignin pathway (EuC4H1, EuC4H2, and EuCAD2), an association study was performed for each of the gene action models (co-dominant, recessive, and dominant) using two methods. Firstly, single-marker association tests were done and 539 tests (49 single nucleotide polymorphisms (SNPs) × 11 traits) were analyzed. After Bonferroni correction with a significance level of P = 0.00102, only four SNPs presented significant association with syringyl and syringyl-to-guaiacyl ratio with an adjusted coefficient of determination varying between 2.6 and 4.4 %. Secondly, a model selection method, the backward approach, was implemented. Similar SNPs were detected by both the backward selection and the individual marker approaches. However, the latter detected new associations with other traits, genes, and SNPs and improved the quality of the model as shown by the BIC criteria and the higher adjusted determination coefficient (1.5 to 8.3 %). Our results reveal that cellulose genes can be associated with lignin traits (syringyl-to-guaiacyl ratio) and stress the possible pleiotropic effect of some genes.
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    • "Environmental influences on qualitative variation in C. japonica heartwood norlignans have been investigated (Ogiyama et al. 1983); however, neither the influence of the environment on quantitative variation nor the influence of genetics is well understood. Although heritability or clonal variation of the amounts of heartwood extracts in tree species such as Pinus radiata (Shelbourne 1997), Pinus pinaster (Pot et al. 2002), and Eucalyptus globulus (Poke et al. 2006) have also been reported, such studies have not been well extensive. In particular, inheritance of the traits of specific heartwood compound is open to further investigation. "
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    ABSTRACT: • Introduction In Cryptomeria japonica, heartwood properties are considered to be affected by specific extractives. It remains unclear whether traits of specific heartwood compounds are under genetic control. • Methods Two major heartwood norlignans, agatharesinol (A) and sequirin C (S), were determined quantitatively and qualitatively in 29 C. japonica plus-tree clones to evaluate their clonal variations and clonal repeatability. • Results The content of two norlignans and their composition (S)mol/((A)mol + (S)mol) varied significantly depending on the clone, suggesting that the biosynthesis of norlignan is genetically regulated in C. japonica. In particular, the clonal repeatability of sequirin C was higher than that of both agatharesinol and total norlignan content. In addition, the clonal repeatability of the norlignan molar ratio was quite high. These results suggested that genetic involvement is greater in the accumulation of sequirin C than agatharesinol. No significant correlation was found between agatharesinol and sequirin C content, or between the total norlignan content and the norlignan molar ratio, suggesting that the formation of agatharesinol and sequirin C in norlignan biosynthesis is independently controlled in C. japonica. • Conclusions It was suggested that the traits of the specific heartwood extractive norlignans were under genetic control in C. japonica.
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    Full-text · Article · Jul 2011 · G3-Genes Genomes Genetics
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