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Arauco is one of the largest forest companies in Chile and it has an intensive breeding and clonal selection program for Eucalyptus globulus, with the main objective to increase forest productivity for the pulp industry. As a new challenge to improve and accelerate operational gain capture, Arauco is incorporating genomic selection as part of the clonal selection strategy. To implement this, an E. globulus clonal population of 600 clones from six field tests was used to train a genomic selection model to predict genetic merit based on single nucleotide polymorphism markers. As a phenotype, Air Dry tones of cellulose per tree was measured and it was the trait correlated with the markers. The predictive ability average to five-folds cross-validation with 20 iterations was 0.71 and the standard deviation was 0.04. In the present communication, the model was used to predict genomic breeding values for a prediction population of 3368 new rooted clones developed at the Arauco's nursery with unknown phenotype. Juvenile leaves of each clone were sampled to extract DNA which was genotyped at 20K markers. The prediction of these clones allowed the selection of 90 superior clones that are currently being propagated to establish validation field trials in the 2024 season. The selected group represent a 2.7% selection intensity and a 6 years reduction in the field testing time. With the results of the validation field trials, new operational clones will be selected to propagate at the nursery, increasing genetic gain and diversity in the commercial plantations. [ABSTRACT FROM AUTHOR]

Key message: This article summarizes advances in cold tolerance, particularly the signaling pathways of cold genes in E. globulus. Eucalyptus globulus is one of the most important hardwood species used for pulp and paper production worldwide, but its productivity is limited by cold temperatures which affect their optimal development and distribution. Several plants increase their freezing tolerance in response to low temperatures pre-conditioning, this mechanism known as cold acclimation, is a result of a combination of physiological, biochemical and metabolic changes which depend on transcriptome modifications. This review explores the current knowledge about responses of E. globulus under cold stress, focusing in the first section on the physiological damage caused by cold stress in this species, whereas the second part deals with how perception of cold temperature can regulate the induction of cold acclimation, and finally, focusing on the molecular response systems involved in the cold response, to synthesize our understanding of the complex response to cold stress in E. globulus. [ABSTRACT FROM AUTHOR]

Key message: Identification of the potential candidate genes involved in drought tolerance in leaves and roots ofEucalyptus globulus. Eucalyptus globulus is one of the most cultivated forest tree species in the world because of its excellent wood properties; however, climate change is affecting its establishment, survival and productivity due to the presence of new events with abiotic and biotic stresses. Among abiotic stresses, drought is becoming a major issue due to long periods of drought in several countries where this species is used in commercial plantations. In this study, RNA-Seq analysis was performed in a tolerant genotype of E. globulus to identify the main genes induced by drought stress (DS) in leaves and roots. A total of 686 sequences in leaves and 438 in roots corresponded to differentially expressed genes (DEGs) when comparing DS plants with control plants. Genes involved in protection against reactive oxygen species (ROS), chaperones, transcription factors and secondary metabolism were upregulated by DS in both tissues. Downregulated genes were involved in photosynthesis, generation of precursor metabolites and energy (leaves), and low oxygen and hormone metabolism (roots). A second experiment was carried out to compare some selected candidate genes between genotypes contrasting in drought tolerance. According to qRT-PCR analysis, genes coding for a bifunctional lipid-transporting protein (EuglLTP2) and geraniol 8 hydroxylase (EuglGER) were induced by drought stress in roots of the tolerant genotype but not in the susceptible genotype. The data generated in this study may form the basis for future research to identify drought tolerance mechanisms in E. globulus. They are also useful for use in genetic improvement programs. [ABSTRACT FROM AUTHOR]

Key message: A set of single-nucleotide polymorphisms (SNPs) was discovered using a de novo transcriptome for radiata pine. The reference transcriptome and SNPs were annotated according to the functional information available in biological databases. A set of SNPs was discovered using a de novo transcriptome assembly for radiata pine in Chile. De novo transcriptome was generated by Illumina sequences and assembled by Trinity. A set of unique genes and transcription factors were identified. All dataset sequences were mapped against the de novo reference transcriptome and SNPs were called. A total of 300,761 SNPs were identified between samples, where 38,730 SNPs had a functional annotation. Since there is little data available of radiata pine-omics, the aim of this work is to provide to the scientific community a de novo transcriptome assembly and a set of SNPs. [ABSTRACT FROM AUTHOR]

The goal of the study was to quantify the effect of different cryoprotective pretreatments on the maturation ability of cryopreserved Pinus radiata embryogenic tissue. Fourteen cell lines were evaluated under five pretreatments: (1) Dimethyl sulfoxide 5% (v/v); (2) Dimethyl sulfoxide 10% (v/v); (3) Dimethyl sulfoxide 5% (v/v) and 0.09 M of L-proline; (4) Dimethyl sulfoxide 10% (v/v) and 0.09 M of L-proline; (5) 0.09 M of L-proline and compared to embryogenic tissue that was not cryopreserved (control). The cell lines were thawed at 37 °C to evaluate the recovery percentage and determine the maturation ability. The recovery rate of all cryopreserved material was significantly lower than the control and material treated with 0.09 M of L-proline, in absent dimethyl sulfoxide, showed the lowest levels of recovery. Regarding the number of embryos, an interaction between pretreatments and the cell lines under evaluation was identified. Moreover, morphological differences in the plants being treated with the most concentrated Dimethyl sulfoxide pretreatment was observed. At the microscopic level, no damage or morphological changes in proembryogenic masses were observed during the post-cryopreservation evaluation. Therefore, the best pretreatment was 5% Dimethyl sulfoxide supplemented with 0.09 M L-proline, allowing the most growth recovery of thawed samples and more cotyledonary embryos (maturation ability). The evaluated responses in presence of cryoprotective elements were genotype dependent. [ABSTRACT FROM AUTHOR]

Key message: EUChip60K is a good option to evaluate clonal identity in a breeding population of E. globulus.Abstract: Breeding populations normally are composed of numerous progenies which become the base for the development of new genetic material for propagation and to advance generations of breeding. Errors in clonal identity could have a great impact on expected gain from the breeding programs. In most breeding programs, a moderate percentage of genetic material is often mislabeled. Molecular markers, such as microsatellites, are being currently used to detect such errors. These markers have been demonstrated to be efficient and low cost for massive analysis of samples in a forest breeding program. However, they have a very low transferability across laboratories and the analysis can be time consuming. In this study, we show the high reproducibility level for genotyping Eucalyptus globulus clones and demonstrate the high ability to identify errors between clones using the EUChip60K, a SNP panel with around 60K SNP markers. Even though EUChip60K is a multi-species array for Eucalyptus, it could be easily applied to an E. globulus clonal program. This is the first case of study to assess the EUChip60K performance to evaluate identity errors in a clonal population of E. globulus. [ABSTRACT FROM AUTHOR]

In Chile, an intensive Eucalyptus globulus clonal selection program is being carried out to increase forest productivity for pulp production. A breeding population was used to investigate the predicted ability of single nucleotide polymorphism (SNP) markers for genomic selection (GS). A total of 310 clones from 53 families were used. Stem volume and wood density were measured on all clones. Trees were genotyped at 12 K polymorphic markers using the EUChip60K genotype array. Genomic best linear unbiased prediction, Bayesian lasso regression, Bayes B, and Bayes C models were used to predict genomic estimated breeding values (GEBV). For cross-validation, 260 individuals were sampled for model training and 50 individuals for model validation, using 2 folds and 10 replications each. The average predictive ability estimates for wood density and stem volume across the models were 0.58 and 0.75, respectively. The average rank correlations were 0.59 and 0.71, respectively. Models produced very similar bias for both traits. When clones were ranked based on their GEBV, models had similar phenotypic mean for the top 10% of the clones. The predicted ability of markers will likely decrease if the models are used to predict GEBV of new material coming from the breeding program, because of a different marker-trait phase introduced by recombination. The results should be validated with larger populations and across two generations before routine applications of GS in E. globulus. We suggest that GS is a viable strategy to accelerate clonal selection program of E. globulus in Chile. [ABSTRACT FROM AUTHOR]

Key message: This work contributes to the identification and understanding of CBF genes and their putative role in the mechanisms of cold tolerance in eucalypt species. Abstract: Three new CBF genes were isolated from E. globulus-denominated Egl CBF1a, c, and d, coding for proteins of 220, 229, and 196 amino acids, respectively. The sequence analysis showed that the three predicted proteins contain an AP2 DNA-binding domain and two CBF signature sequences. Phylogenetic analysis demonstrated that these proteins were highly similar to those described in E. grandis and E. gunnii. Transcript abundance analysis in three different E. globulus genotypes exposed to a cold acclimation treatment showed that these CBF genes were highly related to the acclimation process and presented the highest relative expression at freezing temperatures. Egl CBF1a showed the highest expression level (1311-fold change) in the cold-tolerant genotype (R1). Egl CBF1a and d genes were induced by chilling and freezing temperatures, while Egl CBF1c was constitutively expressed, increasing its transcript level when plants were exposed to freezing temperatures. The constitutive overexpression of each E. globulus CBF gene in Arabidopsis plants induces the endogenous CBF regulon gene expression of Arabidopsis and enhanced its tolerance to freezing, with additional phenotypic effects including growth inhibition and delayed flowering. These results indicate that the three Egl CBF genes analyzed play important roles under cold acclimation processes in E. globulus and are involved in the signaling pathway of cold stress and the freezing tolerance phenotype observed on specific genotypes of this species and in transgenic Arabidopsis lines. [ABSTRACT FROM AUTHOR]

One hundred genotypes of Eucalyptus globulus were ranked according to specific consumption of wood (cubic meters of wood needed to produce 1 ton of pulp). Ten of the most contrasting genotypes were separated in two groups of five clones each; group 1 (G1) with high wood density, high pulp yield, and low specific consumption, and group 2 (G2) with low density, low pulp yield, and high specific consumption. The contrasting genotypes also had significant differences in lignin content, percent syringyl unit composition, and frequency of β- O-4 linkages. Gene expression for phenylalanine ammonia-lyase (PAL), cinnamyl alcohol dehydrogenase (CAD), 4-coumarate:CoA ligase (4CL) and ferulate 5-hydrolase (F5H) was analyzed in the contrasting genotypes. In both groups, transcript abundance for CAD, PAL, and 4CL were similar and only F5H presented significant differences between groups, with high values in the best ranked genotypes G1 in comparison to G2. Correlations between traits were estimated for lignin content vs. pulp yield ( R = 0.97), pulp yield vs. syringyl units ( R = 0.82), β- O-4 linkages vs. pulp yield ( R = 0.84), and β- O-4 linkages vs. syringyl units ( R = 0.97). Correlations between chemical composition and transcript abundance for F5H were calculated, finding correlation values with lignin content ( R = 0.81), syringyl units ( R = 0.83), and pulp yield ( R = 0.81). The measurement of transcript abundance of F5H represents a potential genomic tool for tree improvement programs to select trees with high pulp yield. [ABSTRACT FROM AUTHOR]