Eucalyptus Grandis Research Articles

Impact of moisture and NIR sensors on calibration transfer between predictive models of Eucalyptus grandis wood density

BackgroundEucalyptus urophylla × Eucalyptus grandis (E. urograndis) is a globally significant forest tree species renowned for its rapid growth, high yield, and exceptional wood production efficiency. A comparative analysis of its parental genomes, coupled with an in-depth investigation of the expression patterns of wood-related genes, will provide critical genomic resources to enhance research and utilization of this superior eucalypt hybrid species.ResultsIn this study, we present a draft genome assembly consisting of 592.09 Mb of data, with 99.91% anchored to 11 pseudochromosomes. The assembly achieved a contig N50 of up to 3.73 Mb and a scaffold N50 of up to 58.62 Mb. Gene annotation and evaluation revealed that the E. urograndis genome contains 32,151 genes, of which 93.50% were fully annotated using Benchmarking Universal Single-Copy Orthologs (BUSCOs). Based on evolutionary analysis, E. grandis and E. urograndis are estimated to have diverged approximately 2.90 million years ago (Mya). Additionally, 131 gene families were found to be significantly expanded, and 475 positively selected genes (PSGs) were identified in the E. urograndis genome. Furthermore, RNA sequencing (RNA-seq) technology was employed to analyze allele-specific expression patterns of key enzymes involved in cellulose, xylan, and lignin biosynthesis. Several allele-specific expression genes (ASEGs) were identified, potentially associated with heterosis in E. urograndis.ConclusionsThe chromosomal-level genome assembly of E. urograndis presented in this study serves as a valuable genomic resource for eucalyptus molecular breeding, provides novel insights into its evolution, wood formation improvement, and adaptability, and enhances our understanding of genetic and molecular mechanisms underlying heterosis in Eucalyptus hybrids.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12870-025-07371-3.

Microwave treatment enhances the hygroscopic stability of fast-growing Eucalyptus grandis × urophylla through the synergistic effect of chemical and structural evolution. This study explored the moisture response of earlywood and latewood after microwave treatment, revealing the mechanism of reduced hygroscopicity caused by the coupling of structural and compositional changes. The experimental results showed that the equilibrium moisture content of both earlywood and latewood of Eucalyptus was suppressed under different humidity gradients, and the reduction in earlywood was greater than that in latewood. From a chemical perspective, hemicellulose deacetylation and lignin cross-linking dominated the process of reduced hygroscopicity by consuming hydrophilic groups (–OH/–COOH) and stabilizing the hydrogen bond network. From a structural perspective, steam-induced mesopore expansion and microcrack formation, but these physical changes did not lead to reduced hygroscopicity. Instead, the contradiction between enlarged pores (theoretically conducive to capillary condensation) and suppressed equilibrium moisture content highlights the dominant role of chemical pathway regulation. These findings indicate that the reduction in hygroscopicity of microwave-treated eucalyptus stems from the reduction of chemical hydrophilic group sites and the suppression of capillary effects, which provides a new way to optimize the dimensional stability of tropical hardwood with energy conservation.

IntroductionThe cellulose synthase gene superfamily is composed of two major gene families: cellulose synthase (CesA) and cellulose synthase-like (Csl). These genes play a crucial role in the synthesis of cellulose and hemicellulose within the plant cell wall, and are essential for controlling plant growth and development. However, the CesA/Csls gene family has not been previously reported in Eucalyptus grandis.MethodsIn this study, bioinformatics methods were employed to identify the CesA/Csls gene family inE. grandisand to analyze the potential functions of its members in cell wall formation.ResultsThe results revealed that there were 62 CesA/Csls family members inE. grandis, which were classified into seven subfamilies (CesA, CslA, CslB, CslC, CslD, CslE, CslG) based on evolutionary tree analysis. Promoter regions of these genes contained various cis-acting elements, with light-responsive elements being the most abundant. Gene expression pattern analysis showed that EgCesA4, EgCesA7, and EgCesA8 were highly expressed in the xylem, suggesting their primary association with cellulose synthesis during secondary wall thickening (lignification).DiscussionOverall, the analysis of the EgCesA/Csls gene family provides a valuable reference for understanding cellulose synthesis in the cell wall, genetic improvement, and biotechnological applications.

The present study aimed to evaluate proxy variables to represent the productive capacity of the sites in a forest growth and yield model for plantations of Eucalyptus urophylla × Eucalyptus grandis hybrid, considering them in a linear and a linear mixed model structure. Data from permanent plots in stands located in north-eastern Bahia (Brazil) were used, where there is a high spatial variability of rainfall and different soil types. The variables site index (SI), based on a height-age relationship; mean height of dominant trees (Hd); thirteen soil classes; and six annual rainfall classes (ranging from 850 to 1 200 mm) were used as alternatives to represent the productive capacity. The replacement of the site index (SI) by the mean height of the dominant trees in the Schumacher model resulted in an equation somewhat less accurate than that obtained by using site index (SI), but in the validation model's process provided more accurate estimates. The inclusion of the rainfall or soil classes as a random effect, in a mixed model, instead of the site index (SI), also resulted in somewhat less precise equations as well as less accurate estimates in the validation process. However, despite such results, all the evaluated variables were shown as alternatives to represent the productive capacity of the stands in a forest growth and yield model due to the accuracy of volume estimates in the fitting and validation process.

Context Understanding the extant structure of forests reveals important insights into their ecological condition, age, biodiversity and related ecosystem services. Advances in LiDAR and computational power enable detailed assessments of forest structure at an individual tree resolution over large geographic extents. Aims This study aimed to model and map tree canopy crowns and heights at a landscape scale and investigate the influence of forest type, land use and tenure, and environmental factors on spatial variation in forest height. Methods We utilised publicly available Airborne Laser Scanning (ALS) data to model canopy shape and height for individual trees, across a 3.1 Mha study region in the Northern Rivers region of New South Wales, Australia, employing LiDAR-derived Canopy Height Model (CHM) and Dalponte crown segmentation techniques. Tree heights were subsequently compared between different vegetation formations and stratified by land use and tenure. Key results A total of 180,709,102 tree crowns was identified. The tallest trees included a 81 m tall Eucalyptus grandis specimen and a 77 m tall Araucaria cunninghamii specimen. The analysis of tree heights among vegetation formations and land use/tenure revealed that tree heights were tallest in wet sclerophyll forest, and Nature Conservation and Production Native Forest tenures. Tree crown detection accuracy was high (2.3% difference), although discrepancies were noted in areas affected by severe fires and complex rainforest canopies. Conclusions The results show that LiDAR and advanced modelling techniques can be applied to model map forest canopy structure on an individual tree basis at a landscape scale. Implications These results provide valuable insights into the ecological condition of the region’s forests that can inform management strategies and conservation efforts. The methods can be readily applied to other forested landscapes where airborne LiDAR is available.

The TIFY gene family participates in crucial processes including plant development, stress adaptation, and hormonal signaling cascades. While the TIFY gene family has been extensively characterized in model plant systems and agricultural crops, its functional role in Eucalyptus grandis, a commercially valuable tree species of significant ecological and economic importance, remains largely unexplored. In the present investigation, systematic identification and characterization of the TIFY gene family were performed in E. grandis using a combination of genome-wide bioinformatics approaches and RNA-seq-based expression profiling. Nineteen EgTIFY genes were identified in total and further grouped into four distinct subfamilies, TIFY, JAZ (subdivided into JAZ I and JAZ II), PPD, and ZML, based on phylogenetic relationships. These genes exhibited considerable variation in gene structure, chromosomal localization, and evolutionary divergence. Promoter analysis identified a multitude of cis-acting motifs involved in mediating hormone responsiveness and regulating abiotic stress responses. Transcriptomic profiling indicated that EgJAZ9 was strongly upregulated under methyl jasmonate (JA) treatment, suggesting its involvement in JA signaling pathways. Taken together, these results offer valuable perspectives on the evolutionary traits and putative functional roles of EgTIFY genes.

Malate dehydrogenases are pivotal in plant metabolism and stress responses, yet their evolutionary dynamics and functional diversification in woody angiosperms remain underexplored. This study comprehensively characterized the Eucalyptus grandis MDH (EgMDH) gene family to elucidate its roles in development and environmental adaptation. We identified 14 EgMDH genes and conducted phylogenetic, structural, and syntenic analyses to trace their evolutionary origins. Transcriptional networks were deciphered using cis-regulatory element analysis and protein interaction predictions. Spatiotemporal expression under hormone treatments (JA, SA), abiotic stresses (salt, cold), and nutrient deficiencies (phosphate, nitrogen, and boron) was profiled via transcriptome data or RT-qPCR experiments. Phylogenetics revealed three MDH clades: green algal-derived Groups I/II and red algal-derived Group III. Phylogenetics analysis with model plants revealed that Eucalyptus lacked Group III MDHs, while Poplar lacked Group II members, indicating lineage-specific gene loss in woody angiosperms. Four segmental duplicated paralog pairs (EgMDH1/3, 6/9, 10/11, 12/14) exhibited conserved motifs, exon distributions, and synteny with woody dicots, underscoring structural conservation across angiosperms. Sixty transcription factors (TFs) coordinated EgMDH expression, linking them to energy/stress adaptation and secondary metabolism. Subtype-specific regulators (e.g., GT-2, AIL6, NLP6) exclusively targeted Group II EgMDHs, indicating clade-divergent regulatory networks. EgMDHs showed tissue- and stage-dependent expression, particularly during late adventitious root development. EgMDH genes also exhibited temporally distinct expression patterns under JA treatment, SA treatment, salt stress and cold stress conditions. Notably, eleven EgMDH proteins interacted with PPC1/ASP3, coupling malate metabolism to nitrogen/phosphate homeostasis and C/N balance. Taken together, EgMDH genes displayed phased temporal and tissue-specific expression under Pi/N/B deficiencies. These results revealed that coordinated transcriptional reprogramming and protein interactions of EgMDHs were critical for nutrient stress adaptation. Overall, this study suggested that EgMDH genes underwent lineage-specific diversification and played important roles in development and stress resilience.

Climate extremes threaten the resilience of Eucalyptus plantations, yet hybridization with drought-tolerant species may enhance stress tolerance. This study analyzed xylem anatomical and functional drought responses in commercial Eucalyptus grandis (GG) clones and hybrids: E. grandis × camaldulensis (GC), E. grandis × tereticornis (GT), and E. grandis × urophylla (GU1, GU2). We evaluated vessel traits (water transport), fibers (mechanical support), and wood density (D) in stems and branches. Theoretical stem hydraulic conductivity (kStheo), vessel lumen fraction (F), vessel composition (S), and associations with previous hydraulic and growth data were assessed. While general drought responses occurred, GC had the most distinct xylem profile. This may explain it having the highest performance in different irrigation conditions. Red gum hybrids (GC, GT) maintained kStheo under drought, with stable F and a narrower vessel size, especially in branches. Conversely, GG and GU2 reduced F and S; and stem kStheo declined for a similar F in these clones, indicating vascular reconfiguration aligning the stem with the branch xylem. Almost all clones increased D under drought in any organ, with the highest increase in red gum hybrids. These results reveal diverse anatomical adjustments to drought among clones, partially explaining their growth responses.

Enhanced cellulose enzymatic hydrolysis of pilot-scale steam-exploded Eucalyptus grandis chips with previous acid impregnation for bioethanol production

In 2016, the eucalyptus snout weevil, Gonipterus platensis (Marelli, 1926) was recorded in Antioquia, Colombia. This study evaluated how the species Eucalyptus grandis W. Hill ex Maiden, Eucalyptus urophylla S.T.Blake, and Eucalyptus grandis W.Hill ex Maiden × Eucalyptus urophylla S.T. Blake (Eucalyptus × urograndis) influence the life cycle of G. platensis. Two trials were conducted under natural conditions. The first was carried out in a greenhouse, where the larvae were fed with eucalyptus seedlings, which determined the life cycle. The second trial was conducted in a laboratory, and the larvae were fed with eucalyptus leaves, allowing for the determination of the duration of the larvae instars. It was determined that the embryonic period of G. platensis is 9.10 days, with a longer larval duration in larvae fed with E. grandis. The duration of the pre-pupae and pupal stage was longer in E. urophylla. The life cycle duration was longer in G. grandis (85.87 days). The viability of larvae on the fifth day and the survival rate until emerging as adult were lower in E. urograndis. The study concludes that G. platensis can complete its life cycle on all three eucalyptus species. These finding are relevant for the management of eucalyptus plantations and the integrated management of G. platensis.

Expression of an Eucalyptus grandis Xyloglucan endoglycosylase gene in Nicotiana tabacum confers tolerance to abiotic stress

The online version contains supplementary material available at 10.1007/s12298-025-01623-0.

The aim of this study was to analyze the growth and production of two eucalypt clones grown in a silvopastoral system in the municipality of Coronel Pacheco, MG, Brazil and select the best volumetric model for the clones in this arrangement. This silvopastoral system is composed of two commercial eucalypt hybrids, GG100 and I144 (Eucalyptus urophylla x Eucalyptus grandis), at 79 months of age, planted at a spacing of 14.0 x 2.8 meters, Urochloa decumbens as forage component and grazing by Brangus cattle. A completely randomized design with two treatments (clones) and six replicates (plots) was used. The diameter with bark of all trees in the plots and the total height of the first ten trees were measured, along with a rigorous volume determination of five trees per diameter class to obtain volumetric production and fit the growth and production model. Forest inventory measurements were taken on six occasions from 21 to 79 months of age. The Spurr (1952) model showed a high quality of fit and adjusted coefficient of determination and low residual standard error. The I144 clone showed a larger diameter and higher productivity compared to GG100 clone. And also, higher wood volume and average annual increment (AAI). Both clones showed a high potential to adapt to the region environment, however, I144 clone was the most suitable for use in silvopastoral systems under similar conditions to the study.

Abstract The aim was to determine the biological resistance and chemical properties of the wood of four species from an agroforestry system: Parapiptadenia rigida, Peltophorum dubium, Schizolobium parahyba and a hybrid of Eucalyptus urophylla × Eucalyptus grandis. Mass loss tests were carried out with white rot fungi (Trametes versicolor – TV; Pycnoporus sanguineus – PS; Ganoderma applanatum – GA) and brown rot fungi (Gloeophyllum trabeum – GT), and basic density (BD), lignin, extractives, holocellulose and ash were analyzed. S. parahyba (BD: 277 kg m−3) in combination with the GA fungus obtained the highest mass loss (17.6 %), as well as for brown rot (7.6 %) followed by E. urophylla × E. grandis (8.1 %; BD: 509 kg m−3). P. rigida (BD: 652 kg m−3) and P. dubium (BD: 488 kg m−3) showed lower mass loss to brown rot (3.4 %; 2.3 %) and GA (3.5 %; 3.9 %). The resistance to mass loss of P. rigida and P. dubium can be explained by the higher percentage of extractives and BD, which was validated by the principal component analysis that explained 86 % of the variance. In addition, they highlight the need for specific treatments for more vulnerable wood (S. parahyba), promoting greater efficiency in their use.

ABSTRACTCryphonectria canker is one of the most important diseases of plantation‐grown Eucalyptus spp. in the tropics and Southern Hemisphere. The disease has been known in Florida, USA, for many years, and the causal agents are attributed to two known canker pathogens, Chrysoporthe cubensis (≡ Cryphonectria cubensis) and Microthia havanensis (≡ Endothia havanensis). These identifications were based on morphological characteristics, which are inadequate to recognise cryptic species in the Cryphonectriaceae. In this study, we visited various sites in Florida where Eucalyptus grandis and E. amplifolia trees are cultivated and investigated the presence of cankers. Isolations were made from fungal structures on symptomatic tissues associated with cankers. A total of 41 cultures resembling Cryphonectriaceae spp. were isolated. The isolates were identified based on DNA sequences for the ITS region of the rRNA and sections of the β‐tubulin gene, and confirmed as the three species of Cryphonectriaceae, namely Microthia havanensis, Chrysoporthe cubensis and Chrysoporthe doradensis. Of these, Chrysoporthe doradensis was discovered for the first time in the USA. In addition, this study represents the first record of any Cryphonectriaceae on E. amplifolia , a Eucalyptus species that is poorly studied in terms of disease. Pathogenicity trials on Eucalyptus showed that all three Cryphonectriaceae species could cause disease on these trees, with Chrysoporthe spp. being more aggressive. These findings highlight the importance of continuous monitoring and surveillance to detect emerging pathogens and safeguard the sustainability of Eucalyptus in non‐native forestry systems.

BackgroundEucalyptus is one of the most important fast-growing tree species in the world, and its growth and development are significantly affected by nitrogen and phosphorus. The Amino acid/auxin permease (AAAP) gene family plays key roles in long-distance amino acid transport in plants, but their evolutionary diversity and gene expression analysis in Eucalyptus grandis under nutrient deficiency stress are largely unexplored.ResultsThis study presents the first genome-wide identification and functional characterization of 78 AAAP family genes (EgAAAPs) in Eucalyptus grandis, classified into eight subfamilies. Phylogenetic analysis of 28 species across five evolutionary stages revealed the AAAP family’s classification into three groups: Group III originating from green algae and Groups I-II from mosses. This study underscores lineage-specific expansions (e.g., Eucalyptus AAPs) and algal ancestors as pivotal drivers of functional diversification during early land plant adaptation. Structural analysis revealed subfamily-specific features, including conserved motifs, domain variations, and exon-intron heterogeneity, underpinning functional divergence. Tandem duplication dominated EgAAAP expansion, with syntenic conservation to Populus trichocarpa offering molecular insights into Myrtaceae-Salicaceae divergence. Transcriptional regulatory networks identified 166 transcription factors (MYBs, WRKYs, NACs), with subgroup-specific cis-element enrichment: WRKY binding in Group II and RGA-LIKE1 in Groups I/III, mechanistically linking phosphate/nitrogen signaling. Cross-species interaction hubs of key EgAAAPs (e.g., EgAAAP37, EgAAAP38, EgAAAP41, EgAAAP42, EgAAAP43 and EgAAAP78) with stress-responsive proteins (ABCG40, STP1), amino acid transporters (UMAMITs, CAT5/6), and metal carriers (YSLs) revealed woody plant-specific networks absent in Arabidopsis. Spatiotemporal expression profiling delineated six tissue-specific clusters and dynamic hormonal responses: SA/JA induced temporally distinct modules (early, sustained, delayed), while boron/nitrogen/phosphorus deficiency triggered subgroup- and tissue-dependent regulation.ConclusionsCollectively, this study deciphers the evolutionary innovation, regulatory complexity, and functional specialization of AAAP transporters in Eucalyptus, providing a framework for understanding nutrient signaling and stress resilience in woody plants.

The impacts of climate on forestry will influence the tree species planted for commercial use and the ability to adapt to drastic changes in the environment. These changes have promoted the use of technologies such as remote sensing, to monitor compartments, to aid management in decision-making and planning. The use of time series datasets can aid in the understanding and prediction of compartment functioning and health. This study tested the use of Landsat 8 (spectral range 435–2294 nm) level 2 surface reflectance data and climatic variables (such as solar radiation and vapour pressure deficit) to predict tree sap flow measurements over an 8-year period. Using RapidMiner studio for statistical analysis, gradient boosting trees (GBTs) proved successful in achieving an R 2 of 0.97 and an RMSE of 2.39 LPD. It is noted that of all the species that were tested (i.e. Pinus radiata , P . elliotii , Ocotea bullata , Ilex mitis , Podocarpus latifolius , P . elliotii , Eucalyptus grandis x E . nitens and E . dunnii ), the RMSE was greatly reduced with the exclusion of the pine tree species, to a reduced error rate of 0.78. This suggests that using satellite data, for modelling tree sap flow of pine trees has more variation. Nevertheless, this study has proved successful in forecasting sap flow and will contribute to future research in forest health monitoring, as well as to refine the use of time series information to predict sap flow velocity in forest plantation trees.

IntroductionThe Glycosyltransferase 8 (GT8) family is critically involved in plant cell wall synthesis, yet exhibits significant functional divergence among its members. Despite its importance, systematic characterization of GT8 genes in woody plants remains limited. This study aims to comprehensively analyze the GT8 gene family in Eucalyptus grandis to elucidate its role in cell wall biosynthesis.MethodsWe employed bioinformatics tools to mine the E. grandis whole-genome database. A systematic analysis was conducted, including phylogenetic classification, assessment of physicochemical properties, subcellular localization prediction, gene structure annotation, chromosome mapping, and cis-acting element identification in promoter regions.ResultsFifty-two GT8 family members were identified and classified into four subfamilies: GAUT, GATL, GolS, and PGSIP. Protein molecular weights ranged from 15.75 to 185.00 kD (mean: 49.08 kD). Genes were dispersed across all chromosomes except chromosomes 3 and 7. Promoter analysis revealed ubiquitous hormone-responsive cis-elements and prevalent light-responsive elements. Phylogenetic inference suggested that EgGUX02 and EgGUX04 may mediate glucuronic acid (GlcA) incorporation into xylan side chains, while EgGAUT1 and EgGAUT12 are likely direct contributors to xylan and pectin biosynthesis.DiscussionThis study provides the first genome-wide functional annotation of the GT8 family in E. grandis, revealing subfamily-specific roles in cell wall polymer synthesis. The enrichment of stress- and hormone-responsive promoter elements implies regulatory complexity in cell wall remodeling. Our findings establish a foundation for targeted manipulation of xylan and pectin biosynthesis in woody plants, with potential applications in biomass engineering.

IntroductionCold weather poses a significant challenge to the growth of crops and subtropical tree species like Eucalyptus. Exposure of plants to stressful temperatures generates changes in their physiology resulting from modifications in gene expression and extensive metabolic reorganization. A direct comparison of several biochemical changes under cold exposure of leaf tissues of E. dunnii and E. grandis clones was carried out.MethodsLeaf discs of E. grandis and E. dunnii were initially maintained for 24 h at 25°C and then 4 days at 6°C to induce cold stress. Sampling was conducted at 0 h (control condition), 2 and 4 days. Several biochemical parameters were measured, and an untargeted metabolomics approach based on ultra-high performance liquid chromatography (UHPLC) coupled to linear ion trap mass spectrometry fingerprinting was carried out.ResultsResults indicated distinct cold tolerance strategies in Eucalyptus grandis and Eucalyptus dunnii. Eucalyptus dunnii initiated protective mechanism activation after a 2-day exposure period with the accumulation of sugars and phenolic compounds, whereas E. grandis did so after 4 days, accumulating proline and anthocyanins. PLS-DA based on UHPLC-MS fingerprints revealed a clear species-specific effect across the metabolome. This effect was greater than the differences between cold temperatures. Additionally, this methodology allowed the putative identification of 16 phenolic marker compounds with high discriminant potential to differentiate the cold response in these two species.