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Realistic representations of plant carbon exchange processes are necessary to understand the growth and productivity of forests and to understand how plants will behave in future climate change scenarios. These processes are known to vary over depending on environmental and genetic factors. Here, we used the model by Farquhar et al. (Plant 149:78–90, 1980) to obtain the parameters Vcmax, Jmax and Jmax/Vcmax, and we analyzed the influence of growth temperature and precipitation variables and climatic groups on these parameters for the two functional groups (pine and eucalypt). Our results show that the photosynthetic capacity of forests has a difference between the functional groups, the variables growth temperature and precipitation at 10 and 30 days before physiological measurements influenced photosynthetic parameters, indicated a tendency to increase in photosynthetic capacity, suggesting its acclimatization to the environment. There were no differences between the subtropical and tropical climatic groups, demonstrating an adaptation of the genotypes to the environmental conditions of Brazil. The values of Vcmax, Jmax and Jmax/Vcmax parameters provided in this study expand the database of photosynthetic parameters and can be widely used in modeling studies of planted forests in Brazil. However, they should be interpreted with caution, we recommend specific field studies to fit models and further studies comparing species groups in Brazil. [ABSTRACT FROM AUTHOR]

Natural native forests are rapidly being replaced by anthropogenic forests often with a strong presence of invasive alien plant species. Eucalypt species are widely planted worldwide, with Eucalyptus globulus plantations being particularly expressive in Portugal. Poor forestry practices often lead to the associated expansion of invasive species, such as Acacia dealbata. However, we still know relatively little about the functioning of anthropogenic forests, such as seed and pollen dispersal services. Here, we compared bird abundance and richness and the seed and pollen dispersal networks in both forest types. Anthropogenic forests presented lower bird abundance, and smaller, more simplified, and more random (abundance‐based) seed dispersal services than those of natural forests. Interestingly, the pollen dispersal network was more similar than the seed dispersal network for both forest types and dominated by opportunistic and neutral processes, given the absence of specialized nectarivorous. The proportion of birds transporting seeds decreased, while those carrying pollen significantly increased in the anthropogenic forest compared to the native forest. Our work highlights the impact of anthropogenic forests on bird abundance, with consequences for seed dispersal services and forest regeneration. [ABSTRACT FROM AUTHOR]

Outbreaks of bacterial leaf blight (BLB) frequently affect eucalypt plants under nursery and field conditions in several countries. Although research has been conducted to unveil the causal agent, different bacterial species have been associated with similar disease symptoms in different countries. In order to determine the causal agent of BLB in Brazil, a survey was conducted in nine states to recover bacterial isolates from eucalypt plants exhibiting typical BLB symptoms. A total of 41 yellow‐colony isolates with varying aggressiveness towards a susceptible eucalypt clone were obtained, with 16S rDNA sequences indicating that they belong to the Xanthomonas genus. Rep‐PCR analysis separated the Xanthomonas population affecting eucalypt into six distinct groups revealing its high genetic diversity. The same population formed three clusters together with reference strains of X. citri, X. euvesicatoria and X. phaseoli in a phylogenetic tree constructed with partial dnaK, fyuA, gyrB and rpoD gene sequences. Clustering in the phylogenetic tree was clearly related to grouping based on rep‐PCR. Genome sequence comparisons of representative eucalypt isolates with type strains of validly published Xanthomonas species confirmed that the population consisted of X. citri, X. euvesicatoria and X. phaseoli. Inoculation of tomato, common bean, castor bean and eucalypt plants showed that the representative eucalypt isolates can cause disease in these plant species. Based on the results, the transfer of Xanthomonas axonopodis pv. eucalyptorum to Xanthomonas citri is proposed. These results are relevant for eucalypt BLB management under nursery and field conditions, including selection and deployment of effective plant resistance. [ABSTRACT FROM AUTHOR]

Net rhizodeposition corresponds to the portion of living root carbon (C) that remains in the soil after microbial processing and partial decomposition. Although it is assumed that this C input exerts an important role in the formation of soil organic matter (SOM), its contribution to distinct SOM pools is still not fully understood. In this study, we aimed to (i) quantify the retention of net rhizodeposition C in the different SOM fractions and in reactive Al and Fe mineral phases and (ii) investigate how rhizodeposition drives the spatial distribution of microbial communities in the rhizosphere. To track the transfer of net rhizodeposition into the soil, we used artificially labeled eucalypt (Eucalyptus spp.) seedlings under a 13C-CO2 atmosphere (multiple-pulse labeling). Combining physical SOM fractionation and the chemical extraction of aluminum (Al) and iron (Fe) reactive phases, we studied the distribution of net rhizodeposition into different soil fractions. We also assessed the 13C incorporation into microbial phospholipid fatty acids (PLFAs) at different distances from the roots. Our results show that 76 % of the net rhizodeposition 13C was retained within the mineral-associated organic matter (MAOM) fraction. About 28 % of net rhizodeposition 13C within the MAOM fraction was retained within the Al and Fe reactive phases, indicating that this is a sizeable mechanism for the retention of net rhizodeposition in soil. Rhizodeposition increased the abundance of microbial PLFAs exclusively in the soil close to the roots (0–4 mm), with prominent incorporation of net rhizodeposition 13C into fungal biomarkers. Overall, our findings underscore the importance of mineral associations for the retention of net rhizodeposition in the soil. We also highlight the role of fungi in transferring the root-derived C beyond the root vicinity and promoting the formation of occluded SOM.

Wood residues, as well as those from poultry farming, are generally disposed of irregularly, which causes damage to the environment, and thus poses a great challenge in terms of their use, a possible alternative is the manufacture of particleboards. For this, the following mechanical properties of the panels were evaluated: static bending (elasticity – MOE and rupture – MOR), internal bond strength (IB), Janka hardness (DJ), screw withdrawal resistance (SW), thickness swelling (TS), water absorption (WA), moisture, apparent density (DA) and density profile, in addition to morphological characterization by scanning electron microscope image. With the results obtained, it was possible to observe that the amount of residue influenced the density of the panel. The panel compaction ratio showed little variation (1.22–1.32), remaining close to the value considered ideal of 1.33. The percentage of waste added to the panels also influenced the increase in WA and TS, limiting the use of the panels to environments without humidity. The addition of the eggshell in the process negatively affected the mechanical characteristics of formulated particleboards, except for Janka hardness. The application of the resin together with the wood particles and eggshells can improve the mechanical properties. Based on the findings from this study, the medium-density particleboard produced can be used for making furniture and room partitioning without structural character.

Expansive soils undergo significant moisture change under prevailing climate conditions, resulting in shrinkage and swelling in dry and wet months. Such seasonal movements of expansive soils can greatly affect the serviceability and performance of lightweight structures founded on shallow footing systems. The extent of movement may be exacerbated if trees are present since large amounts of water can be absorbed by the root system of trees, leading to localized settlement due to soil shrinkage. This study established a well-instrumented site that included a row of Australian native eucalypts located in an eastern suburb of Melbourne, Australia. A tree from this row was chosen for the monitoring of soil movements, soil moisture and suction over a period of 44 months. A sap flow instrument was used to monitor the transpiration and water uptake by the tree. The results showed that noticeable shrinkage settlement occurred at a radial distance of 7.8 m from the trunk of the tree, attributable in part to the increased water demand of the tree. This study promotes a better understanding of the process of expansive soil–tree root interaction. The field data presented can assist geotechnical engineers and practitioners with footing design in the presence of trees. [ABSTRACT FROM AUTHOR]

Powdery mildews are biotrophic ascomycetes that do not typically kill their hosts, but instead interfere with normal plant growth. In Indonesia, white powdery spots were observed forming on the upper part of fully developed leaves of Eucalyptus pellita planted in sand beds of a clonal nursery. Thus, this study aimed to identify the causal agent of eucalypt powdery mildew in Indonesia as well as to develop control strategies to better manage the disease. Pathogen identification was based on morphology, molecular characterization of DNA sequencing the ITS region and pathogenicity test. In addition, considering that some powdery mildews are inhibited by free moisture on leaves, efficacy of foliar watering was tested for disease control. Phylogenetic analyses showed that isolates collected from infected eucalypt plants grouped together with other sequences of the Erysiphe elevata clade with bootstrap support of 99%; a similar result was also confirmed by morphological observations. Pathogenicity of powdery mildew on eucalypt plants was confirmed through artificial inoculation, thus fulfilling the Koch's postulates. For disease control, foliar watering reduced the incidence of powdery mildew on mother plants. The reduction of the disease incidence began to be more evident at 2 weeks after trial establishment, and in the fourth week, the incidence was below 10% in all three treatments, while the control was above 20%. Therefore, we concluded that E. elevata is the causal agent of powdery mildew in Indonesia and that one application of foliar watering per week was enough to minimize the disease impact in the nursery. [ABSTRACT FROM AUTHOR]

Austropuccinia psidii is a biotrophic fungus that causes myrtle rust. First described in Brazil, it has since spread to become a globally important pathogen that infects more than 480 myrtaceous species. One of the most important commercial crops affected by A. psidii is eucalypt, a widely grown forestry tree. The A. psidii–Eucalyptus spp. interaction is poorly understood, but pathogenesis is likely driven by pathogen-secreted effector molecules. Here, we identified and characterized a total of 255 virulence effector candidates using a genome assembly of A. psidii strain MF-1, which was recovered from Eucalyptus grandis in Brazil. We show that the expression of seven effector candidate genes is modulated by cell wax from leaves sourced from resistant and susceptible hosts. Two effector candidates with different subcellular localization predictions, and with specific gene expression profiles, were transiently expressed with GFP-fusions in Nicotiana benthamiana leaves. Interestingly, we observed the accumulation of an effector candidate, Ap28303, which was upregulated under cell wax from rust susceptible E. grandis and described as a peptidase inhibitor I9 domain-containing protein in the nucleus. This was in accordance with in silico analyses. Few studies have characterized nuclear effectors. Our findings open new perspectives on the study of A. psidii–Eucalyptus interactions by providing a potential entry point to understand how the pathogen manipulates its hosts in modulating physiology, structure, or function with effector proteins. [ABSTRACT FROM AUTHOR]

Tropical savannas are characterized by high primary productivity and high fire frequency, such that much of the carbon captured by vegetation is rapidly returned to the atmosphere. Hence, there have been suggestions that management‐driven reductions in savanna fire frequency and/or severity could significantly reduce greenhouse gas emissions and sequester carbon in tree biomass. However, a key knowledge gap is the extent to which savanna tree biomass will respond to modest shifts in fire regimes due to plausible, large‐scale management interventions. Here, we: (1) characterize relationships between the frequency and severity of fires and key demographic rates of savanna trees, based on long‐term observations in vegetation monitoring plots across northern Australia; (2) use these relationships to develop a process‐explicit demographic model describing the effects of fire on savanna tree populations; and (3) use the demographic model to address the question: to what extent is it feasible, through the strategic application of prescribed burning, to increase tree biomass in Australian tropical savannas? Our long‐term tree monitoring dataset included observations of 12,344 tagged trees in 236 plots, monitored for between 3 and 24 years. Analysis of this dataset showed that frequent high‐severity fires significantly reduced savanna tree recruitment, survival, and growth. Our demographic model suggested that: (1) despite the negative effects of frequent high‐severity fires on demographic rates, savanna tree biomass appears to be suppressed by only a relatively small amount by contemporary fire regimes, characterized by a mix of low‐ to high‐severity fires; and (2) plausible, management‐driven reductions in the frequency of high‐severity fires are likely to lead to increases in tree biomass of about 11.0 t DM ha−1 (95% CI: −1.2–20.8) over a century. Accounting for this increase in carbon storage could generate significant carbon credits, worth, on average, three times those generated annually by current greenhouse gas (methane and nitrous oxide) abatement projects, and has the potential to significantly increase the economic viability of fire/carbon projects, thereby promoting ecologically sustainable management of tropical savannas in Australia and elsewhere. This growing industry has the potential to bring much‐needed economic activity to savanna landscapes, without compromising important natural and cultural values. [ABSTRACT FROM AUTHOR]

Forest residue, such as stump and coarse roots, can contribute to an increase in the raw material supply from fast-growing Eucalyptus plantations for industrial uses, such as power generation, process wood and biotechnology. However, the impact real on the nutritional sustainability of forest sites because to utilization of belowground biomass is not known. The present study aimed to evaluate the impact of utilization of above and belowground biomass components on the nutritional sustainability of Eucalyptus clonal plantation. To do so, we used Eucalyptus urophylla clones (AEC 0144); E. urophylla × E. grandis (AEC 0224), and E. urophylla × E. camaldulensis (VM01) aged 6.8, 6.6, and 6.3 years of age, respectively. Trees were felled, up-rooted, and separated into leaves, branches, bark, stem wood, stumps, crown root, and coarse roots. Biomass production, stock, and export of N, P, K, Ca, and Mg were analyzed. Moreover, the number of rotations required to export all soil nutrients, and nutrient use efficiency in different harvest systems were determined. The complete tree and full tree harvest systems exported the highest N, P, K, Ca, and Mg amounts, and showed the lowest nutrient use efficiency. This shows the importance of maintaining waste, such as leaves, branches, and bark, on the site. In harvest system debarked stem wood with belowground biomass, intermediate values were obtained in terms of export, use efficiency and number of rotations required to export N, P, K, Ca, and Mg, when compared to other harvest systems. These results showed that the belowground biomass use, taking into consideration Eucalyptus clone selection, and harvest systems can be an alternative source of biomass, without reducing the forest site sustainability and future productivity. [ABSTRACT FROM AUTHOR]

The UN decade on ecosystem restoration calls for the preservation of global biodiversity. Safeguarding biological diversity is crucial for the well‐being of people and the persistence of nature. Tree planting offers a nature‐based solution to carbon abatement with significant potential to benefit biodiversity, but how well different aspects of biodiversity are captured in plantings is not well known.We assemble a database of 218 species and >80,000 observations from environmental tree plantings in Australia, and investigate how well they capture eucalypt diversity, including possible climate change effects. We compare this to hypothetical planting scenarios that maximize biodiversity benefits for species of conservation interest. Eucalypt species that are rare, endemic, evolutionarily distinct or listed in the Environment Protection and Biodiversity Act (EPBC) are prioritized.We find that environmental tree plantings are dominated by very common species likely to benefit from climate change, with less than 1% of rare or evolutionarily distinct species represented. All conservation scenarios outperform business‐as‐usual. The scenario prioritizing endemic species while considering climate change more than doubles the average extent of occurrence for species of conservation interest. It allocates four times more planting area to species of conservation interest compared to a business‐as‐usual approach and decreases weighted endemism (a favourable outcome here) by 38% on average, demonstrating the positive impact of conservation‐focused tree planting on biodiversity.Synthesis and applications. Everywhere, governments are making commitments to halt biodiversity loss. Conservation‐focused tree planting can advance our goal of safeguarding biodiversity while still contributing to carbon capture. We show that eucalypt species of conservation interest can benefit substantially from tree planting where the primary goal is biodiversity conservation, compared to the current approach to planting, which we have found largely benefits commonly occuring species. We measure potential distribution gains for eucalypt species that are rare, endemic, evolutionarily distinct and at risk of extinction (listed), and identify the most important eucalypt species to plant across Australia, taking the effects of climate change into account. Our framework for selecting species to plant based on a range of conservation goals can serve as a guide for future environmental tree planting initiatives. [ABSTRACT FROM AUTHOR]

Introduction: Translocation is a valuable and increasingly used strategy for the management of both threatened and overabundant wildlife populations. However, in some instances the translocated animals fail to thrive. Differences in diet between the source and destination areas may contribute to poor translocation outcomes, which could conceivably be exacerbated if the animals' microbiomes are unsuited to the new diet and cannot adapt. Methods: In this study we tracked how the faecal microbiome of a specialist Eucalyptus folivore, the koala (Phascolarctos cinereus), changed over the course of a year after translocation. We assessed microbiome composition by 16S rRNA amplicon sequencing of faecal pellets. Results: We found no significant overall changes in the faecal microbiomes of koalas post-translocation (n = 17) in terms of microbial richness, diversity or composition when compared to the faecal microbiomes of koalas from an untranslocated control group (n = 12). This was despite the translocated koalas feeding on a greater variety of Eucalyptus species after translocation. Furthermore, while differences between koalas accounted for half of the microbiome variation, estimated diets at the time of sampling only accounted for 5% of the variation in the koala microbiomes between sampling periods. By contrast, we observed that the composition of koala faecal microbiomes at the time of translocation accounted for 37% of between koala variation in post-translocation diet. We also observed that translocated koalas lost body condition during the first month post-translocation and that the composition of the koalas' initial microbiomes were associated with the magnitude of that change. Discussion: These findings suggest that the koala gut microbiome was largely unaffected by dietary change and support previous findings suggesting that the koala gut microbiome influences the tree species chosen for feeding. They further indicate that future research is needed to establish whether the koalas' gut microbiomes are directly influencing their health and condition or whether aspects of the koala gut microbiomes are an indicator of underlying physiological differences or pathologies. Our study provides insights into how animal microbiomes may not always be affected by the extreme upheaval of translocation and highlights that responses may be host species-specific. We also provide recommendations to improve the success of koala translocations in the future. [ABSTRACT FROM AUTHOR]

IntroductionTranslocation is a valuable and increasingly used strategy for the management of both threatened and overabundant wildlife populations. However, in some instances the translocated animals fail to thrive. Differences in diet between the source and destination areas may contribute to poor translocation outcomes, which could conceivably be exacerbated if the animals’ microbiomes are unsuited to the new diet and cannot adapt.MethodsIn this study we tracked how the faecal microbiome of a specialist Eucalyptus folivore, the koala (Phascolarctos cinereus), changed over the course of a year after translocation. We assessed microbiome composition by 16S rRNA amplicon sequencing of faecal pellets.ResultsWe found no significant overall changes in the faecal microbiomes of koalas post-translocation (n = 17) in terms of microbial richness, diversity or composition when compared to the faecal microbiomes of koalas from an untranslocated control group (n = 12). This was despite the translocated koalas feeding on a greater variety of Eucalyptus species after translocation. Furthermore, while differences between koalas accounted for half of the microbiome variation, estimated diets at the time of sampling only accounted for 5% of the variation in the koala microbiomes between sampling periods. By contrast, we observed that the composition of koala faecal microbiomes at the time of translocation accounted for 37% of between koala variation in post-translocation diet. We also observed that translocated koalas lost body condition during the first month post-translocation and that the composition of the koalas’ initial microbiomes were associated with the magnitude of that change.DiscussionThese findings suggest that the koala gut microbiome was largely unaffected by dietary change and support previous findings suggesting that the koala gut microbiome influences the tree species chosen for feeding. They further indicate that future research is needed to establish whether the koalas’ gut microbiomes are directly influencing their health and condition or whether aspects of the koala gut microbiomes are an indicator of underlying physiological differences or pathologies. Our study provides insights into how animal microbiomes may not always be affected by the extreme upheaval of translocation and highlights that responses may be host species-specific. We also provide recommendations to improve the success of koala translocations in the future.

Kraft lignin, a side-stream from the pulp and paper industry, can be modified by laccases for the synthesis of high added-value products. This work aims to study different laccase sources, including a bacterial laccase from Streptomyces ipomoeae (SiLA) and a fungal laccase from Myceliophthora thermophila (MtL), for kraft lignin polymerization. To study the influence of some variables in these processes, a central composite design (CCD) with two continuous variables (enzyme concentration and reaction time) and three levels for each variable was used. The prediction of the behavior of the output variables (phenolic content and molecular weight of lignins) were modelled by means of response surface methodology (RSM). Moreover, characterization of lignins was performed by Fourier-transform infrared (FTIR) spectroscopy and different nuclear magnetic resonance (NMR) spectroscopy techniques. In addition, antioxidant activity was also analyzed. Results showed that lignin polymerization (referring to polymerization as lower phenolic content and higher molecular weight) occurred by the action of both laccases. The enzyme concentration was the most influential variable in the lignin polymerization reaction within the range studied for SiLA laccase, while the most influential variable for MtL laccase was the reaction time. FTIR and NMR characterization analysis corroborated lignin polymerization results obtained from the RSM. [ABSTRACT FROM AUTHOR]

The usage of laccases is a sustainable and environmentally friendly approach to modifying the Kraft lignin structure for use in certain applications. However, the inherent structure of Kraft lignin, as well as that resulting from laccase modification, still presents challenges for fundamental comprehension and successful lignin valorization. In this study, bacterial and fungal laccases were employed to modify eucalypt Kraft lignin. To evaluate the type and range of the chemical and structural changes of laccase-treated lignins, different NMR techniques, including solution 1H and 2D NMR (heteronuclear single quantum correlation (HSQC)), and solid-state 13C NMR, were applied. Size exclusion chromatography and infrared spectroscopy were also used. Interestingly, HSQC analysis showed substantial changes in the oxygenated aliphatic region of lignins, showing an almost complete absence of signals corresponding to side-chains due to laccase depolymerization. Simultaneously, a significant loss of aromatic signals was observed by HSQC and 1H NMR, which was attributed to a deprotonation of the lignin benzenic rings due to polymerization/condensation by laccase reactions. Then, condensed structures, such as α-5′, 5-5′, and 4-O-5′, were detected by HSQC and 13C NMR, supporting the increment in molecular weight, as well as the phenolic content reduction determined in lignins. [ABSTRACT FROM AUTHOR]

Erwinia psidii (Eps) is the causal agent of emerging diseases of eucalypt and guava; however, the mechanisms underlying its pathogenicity are not fully understood. Here, we predicted factors involved in the ability of Eps to cause disease on its host plants. For that, the genomes of four Eps strains exhibiting different virulence on eucalypt were sequenced, and hrp/hrc genes coding for the type III secretion system (T3SS), effectors injected into the plant cell cytoplasm through the T3SS (T3SEs) and their plant subcellular localizations, as well as proteins deployed to the host apoplast, were predicted. It was found that Eps possesses a complete hrp/hrc gene cluster based on comparison with Erwinia amylovora. A total of 18 T3SEs were predicted, 11 of which were shared among all strains, none were exclusive to any strain and seven were absent in at least one strain. No sequence variation among strains was found for five T3SE candidates whereas extensive variation was found for six, suggesting the latter may be determinants of virulence differences. The T3SE candidates are predicted to target the plant cell nucleus, cytoplasm, mitochondrion, chloroplast and peroxisome. The predicted apoplastic effector repertoire common to all four strains was over‐represented in proteins of unknown functions or predicted to possess enzymatic activities, among which the most abundant were oxidoreductases and peptidases. Proteins with lytic transglycosylase activity were predicted in strain‐specific apoplastic effector repertoires. These results provide an important framework for future research aimed at uncovering the factors underlying Eps pathogenicity. [ABSTRACT FROM AUTHOR]

Despite the reported allelopathic nature of the Eucalyptus genus, eucalypt leachates have unknown effects on the trophic base of stream green food webs. Eucalypt plantations have increased worldwide, including riparian ecosystems. We aimed to test whether short-term eucalypt leachates might alter water chemistry, periphytic algal biomass and diatoms, and herbivorous invertebrates' (i.e., scrapers). We studied two oligotrophic and well-preserved headwaters from NW Spain. The experiment followed a before-after control-impact paired (BACIp) design, with weekly sampling before and after eucalypt leaves addition to streams. In the stream with lower discharge, the eucalypt treatments seemed to affect increases in biomass accrual (Chl-a) and diatom assemblages, disfavouring sensitive species (e.g., Eunotia minor and Achnanthidium pyrenaicum). Therefore, the ecological status was reduced from high to good. In the stream with higher discharge, invertebrate assemblages changed with scrapers having their abundances modified in comparison with the control (e.g., Habrophlebia sp. and Elmidae). Results suggest that eucalypt leaves leachates exert toxic effects on periphyton and on diatom and invertebrate assemblages, and this effect might be mediated by discharge. Alterations at the base of stream food webs may compromise their good ecological status. Further studies are necessary to identify whether this toxicity is due to allelopathic processes. [ABSTRACT FROM AUTHOR]

The resilience of forests worldwide is challenged by climate change. Large-scale tree mortality and dieback events have been documented across continents in recent decades. The adaptive capacity of forests is important for predicting forest resistance and resilience to future climates yet remains largely unknown. We grew 12 populations of a widespread foundation tree species (Corymbia calophylla), originating from different temperature and rainfall regimes, in two common garden trials in Western Australia that had similar temperature but contrasting rainfall conditions. We quantified intraspecific trait variation at these two sites to estimate genetically determined trait variation with climate origin (genetic adaptation) and trait variation associated with environment (phenotypic plasticity). We aimed to determine the 1) contribution of genetic and environmental factors on growth, functional, and physiological trait variation; 2) coordination of leaf traits within the context of the leaf economic spectrum (LES) in variable rainfall conditions; and 3) role of local or regional climate adaptation influencing tree growth and water use efficiency. Growth and physiological traits were differentially expressed across populations and sites, highlighting the importance of genetic adaptation and phenotypic plasticity. Leaf traits reflected a more water conservative strategy with higher water use efficiency, high foliar nitrogen content, and low specific leaf area, as predicted by the LES, in trees at the dry site measured in autumn after the warm summer. Local adaptation was detected in growth and leaf water use efficiency traits at the regional climate, not the local population, scale. Plants from the cool region had greater performance than those from the warm region in most plant traits. Home-site rainfall was not a good predictor of trait expression. The capacity of C. calophylla to respond to low water availability through genetic adaptation and phenotypic plasticity may enable it to maintain optimal performance in drier conditions associated with climate change. • Leaf traits were coordinated and reflected a water conservative strategy. • Growth and leaf water use efficiency traits were locally adapted. • Plant traits expressed phenotypic plasticity to site rainfall. • Regional temperature was a stronger driver of plant traits than rainfall. [ABSTRACT FROM AUTHOR]

South Africa has 1.2 million hectares of plantations developed progressively through the 20th century. These occur from 23° to 34°S, from near sea level to 2 000 m above sea level and in both Mediterranean winter rainfall and summer subtropical rainfall climates. Plantations supply pulp mills, sawmills, treated pole and mining timber production, and wattle tannin production. The diversity of sites and markets requires planting of a range of taxa of pine, eucalypt and wattle. A survey of planted area by taxa in South African forest plantations is reported and compared to statistics available from national annual reporting on the commercial timber resources in the country. The survey found a similar number of taxa are currently planted (15) as in the 1950s but only 6 of the earlier options remain in use. Changes have occurred in the last 30 years, with 40% of planted area in 2019 using options not available before 1990. From the 1990s, Eucalyptus grandis has been extensively replaced by eucalypt hybrids and E. dunnii and Pinus elliottii × P. caribaea var. hondurensis has become an important pine planting option. Over the past decade, E. nitens replacement with other existing frost tolerant eucalypt planting options has occurred, use of P. radiata has reduced and P. patula has been replaced on a significant scale with P. patula hybrids. Many of these changes have been to mitigate the impact of new pests and pathogens and, on lower productivity sites, periodic severe droughts. However, the new planting options also provide increased yields and have wood properties acceptable to the intended markets. Meeting all three criteria is likely to remain a requirement for successful introduction of future new planting options. The survey indicates a need to revise current national reporting requirements to better reflect use of species and hybrids in South African plantations. [ABSTRACT FROM AUTHOR]

This article presents a method, based on orbital remote sensing, to map the extent of forest plantations in São Paulo State (Southeast Brazil). The proposed method uses the random forest machine learning algorithm available on the Google Earth Engine (GEE) cloud computing platform. We used 30 m annual mosaics derived from Landsat-5 Thematic Mapper (TM) images and from Landsat-8 Operational Land Imager (OLI) images for the 1985 to 1995 and 2013 to 2021 time periods, respectively. These time periods were selected based on the planted areas' rotation, especially the eucalypt's short rotation. To classify the forest plantations, green, red, NIR, and MIR spectral bands, NDVI, GNDVI, NDWI, and NBR spectral indices, and vegetation, shade, and soil fractions were used for both sensors. These indices and the fraction images have the advantage of reducing the volume of data to be analyzed and highlighting the forest plantations' characteristics. In addition, we also generated one mosaic for each fraction image for the TM and OLI datasets by computing the maximum value through the period analyzed, facilitating the classification of areas occupied by forest plantations in the study area. The proposed method allowed us to classify the areas occupied by two forest plantation classes: eucalypt and pine. The results of the proposed method compared with the forest plantation areas extracted from the land use and land cover maps, provided by the MapBiomas product, presented the Kappa values of 0.54 and 0.69 for 1995 and 2020, respectively. In addition, two pilot areas were used to evaluate the classification maps and to monitor the phenological stages of eucalypt and pine plantations, showing the rotation cycle of these plantations. The results are very useful for planning and managing planted forests by commercial companies and can contribute to developing an automatic method to map forest plantations on regional and global scales. [ABSTRACT FROM AUTHOR]

Plant secondary metabolites (PSMs) can influence the consumption of particular plants by herbivores. Unsubstituted B-ring flavanones (UBFs), which are compounds found in the leaves of Eucalyptus species from the Eucalyptus subgenus (common name monocalypt), deter feeding by common brushtail possums (Trichosurus vulpecula ) when added to artificial diets at concentrations that reflect those found naturally in foliage. We hypothesised that common ringtail possums (Pseudocheirus peregrinus ) would tolerate higher UBF concentrations, because, unlike brushtail possums, they regularly eat monocalypt foliage. This proved to be the case; ringtail possums were not deterred by two different UBFs, pinocembrin and flavanone, at concentrations up to 4.7% dry matter, which is substantially higher than the concentrations that deter brushtail possums. These results extend and refine our understanding of how variation in tolerance or susceptibility to eucalypt PSMs affects the diets of sympatric marsupial folivores, potentially reducing competition for food. [ABSTRACT FROM AUTHOR]

Summary: From its origins in Australia, Eucalyptus grandis has spread to every continent, except Antarctica, as a wood crop. It has been cultivated and bred for over 100 yr in places such as South Africa. Unlike most annual crops and fruit trees, domestication of E. grandis is still in its infancy, representing a unique opportunity to interrogate the genomic consequences of artificial selection early in the domestication process.To determine how a century of artificial selection has changed the genome of E. grandis, we generated single nucleotide polymorphism genotypes for 1080 individuals from three advanced South African breeding programmes using the EUChip60K chip, and investigated population structure and genome‐wide differentiation patterns relative to wild progenitors.Breeding and wild populations appeared genetically distinct. We found genomic evidence of evolutionary processes known to have occurred in other plant domesticates, including interspecific introgression and intraspecific infusion from wild material. Furthermore, we found genomic regions with increased linkage disequilibrium and genetic differentiation, putatively representing early soft sweeps of selection.This is, to our knowledge, the first study of genomic signatures of domestication in a timber species looking beyond the first few generations of cultivation. Our findings highlight the importance of intra‐ and interspecific hybridization during early domestication. [ABSTRACT FROM AUTHOR]

Fire regimes are changing across the globe in response to complex interactions between climate, fuel, and fire across space and time. Despite these complex interactions, research into predicting fire regime change is often unidimensional, typically focusing on direct relationships between fire activity and climate, increasing the chances of erroneous fire predictions that have ignored feedbacks with, for example, fuel loads and availability. Here, we quantify the direct and indirect role of climate on fire regime change in eucalypt dominated landscapes using a novel simulation approach that uses a landscape fire modelling framework to simulate fire regimes over decades to centuries. We estimated the relative roles of climate‐mediated changes as both direct effects on fire weather and indirect effects on fuel load and structure in a full factorial simulation experiment (present and future weather, present and future fuel) that included six climate ensemble members. We applied this simulation framework to predict changes in fire regimes across six temperate forested landscapes in south‐eastern Australia that encompass a broad continuum from climate‐limited to fuel‐limited. Climate‐mediated change in weather and fuel was predicted to intensify fire regimes in all six landscapes by increasing wildfire extent and intensity and decreasing fire interval, potentially led by an earlier start to the fire season. Future weather was the dominant factor influencing changes in all the tested fire regime attributes: area burnt, area burnt at high intensity, fire interval, high‐intensity fire interval, and season midpoint. However, effects of future fuel acted synergistically or antagonistically with future weather depending on the landscape and the fire regime attribute. Our results suggest that fire regimes are likely to shift across temperate ecosystems in south‐eastern Australia in coming decades, particularly in climate‐limited systems where there is the potential for a greater availability of fuels to burn through increased aridity. [ABSTRACT FROM AUTHOR]

Abstract Comments are presented on an article published in October 2020 in Ecology and Evolution (“Predictive ability of a process‐based versus a correlative species distribution model”) by Higgins et al. This analyzed natural distributions of Australian eucalypt and acacia species and assessed the adventive range of selected species outside Australia. Unfortunately, inappropriate variables were used with the MaxEnt species distribution model outside Australia, so that large climatically suitable areas in the Northern Hemisphere were not identified. Examples from a previous analysis and from the use of the freely available spatial portal of the Atlas of Living Australia are provided to illustrate how the problem can be overcome. The comparison of methods described in the Higgins et al. paper is worthwhile, and it is hoped that the authors will be able to repeat their analyses using appropriate variables with the correlative model.

Austropuccinia psidii is a biotrophic fungus that causes myrtle rust. First described in Brazil, it has since spread to become a globally important pathogen that infects more than 480 myrtaceous species. One of the most important commercial crops affected by A. psidii is eucalypt, a widely grown forestry tree. The A. psidii–Eucalyptus spp. interaction is poorly understood, but pathogenesis is likely driven by pathogen-secreted effector molecules. Here, we identified and characterized a total of 255 virulence effector candidates using a genome assembly of A. psidii strain MF-1, which was recovered from Eucalyptus grandis in Brazil. We show that the expression of seven effector candidate genes is modulated by cell wax from leaves sourced from resistant and susceptible hosts. Two effector candidates with different subcellular localization predictions, and with specific gene expression profiles, were transiently expressed with GFP-fusions in Nicotiana benthamiana leaves. Interestingly, we observed the accumulation of an effector candidate, Ap28303, which was upregulated under cell wax from rust susceptible E. grandis and described as a peptidase inhibitor I9 domain-containing protein in the nucleus. This was in accordance with in silico analyses. Few studies have characterized nuclear effectors. Our findings open new perspectives on the study of A. psidii–Eucalyptus interactions by providing a potential entry point to understand how the pathogen manipulates its hosts in modulating physiology, structure, or function with effector proteins.

Aim: Eucalypts have a widespread global distribution owing to their popularity for agroforestry and as environmental plantings. Despite an abundance of site‐specific evidence that eucalypts modify soils and soil processes, we lack a quantitative synthesis of their overall effects at the global scale. This limits our capacity to assess the likely impacts of future introductions in any given region of the world. Location: Global. Time period: 1986–2021. Major taxa studied: Eucalyptus, Angophora and Corymbia. Methods: We used a systematic search to derive a database of empirical data from 227 studies across 33 countries (neffect size = 2,806) and tested three predictions about the effects of eucalypts on soil properties and whether these effects varied with plantation age and soil depth. Results: Compared with (non‐eucalypt) native vegetation, eucalypts significantly reduced soil moisture, microbial abundance, nitrogen, cations and anions. Relative reductions in soil microbes and ions were stronger in older eucalypt plantations. A comparison of eucalypts with (non‐eucalypt) silvicultural and agropastoral systems revealed similar effects on most soil properties, although eucalypts tended to reduce potassium and enhance carbon to a greater extent than other managed systems. We found no consistent effects of eucalypts on soil pH. Main conclusions: Our study provides the first extensive global meta‐analysis of the effects of eucalypts on soil properties and processes and demonstrates that effects are highly dependent on the community with which they are compared (i.e., natural or managed). In general, our findings reinforce the widely held belief that eucalypts deplete soil nutrients and dominate water resources. Understanding how eucalypts affect soils allows us to assess their global suitability for agroforestry, soil rehabilitation and soil carbon enhancement, while considering the potential environmental costs. [ABSTRACT FROM AUTHOR]

Elevated atmospheric [CO2] ('eCO2') may alter species composition within vegetation types by favouring the growth of some species over others. However, other related changes in climate conditions, such as increased frequency and severity of drought, may reduce eCO2 fertilisation effects on plant growth. For many species, it is not known if responses will reflect variability in trait adaptations due to environment.We grew seedlings of nine species of eucalypts indicative of three regional vegetation types (representing a mesic–xeric ecosystem gradient) under two CO2 concentrations (400 parts per million; 640 ppm, i.e. eCO2) and two watering regimes (well‐watered; drought‐like conditions).Elevated CO2 increased biomass accumulation but drought reduced this effect, with mesic species experiencing larger relative reductions. Elevated CO2 increased the size of storage organs used during resprouting, in the absence of drought. Typical drought responses, such as increased leaf mass per unit area and root mass ratio, were more pronounced in xeric species and were reduced under eCO2.Seedling growth and resprouting may be enhanced by eCO2, suggesting continued dominance of resprouting species in disturbance‐prone ecosystems, although severe drought is likely to offset eCO2 fertilisation. Xeric species may cope with drought more effectively under eCO2 than mesic species due to resource acquisition and storage traits that are more responsive. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The bark of an Eucalyptus urophylla hybrid clone used by the charcoal industry was studied regarding anatomy and chemical composition, including the characterization of its polar extracts, in view of its potential use. The bark is characterized by a dominant homogeneous phloem with little ray expansion and alterations in the non-conducting phloem and by a rhytidome with a large portion of dead phloem tissue between the periderms. The cell proportion was axial parenchyma 37.9%, fibers 26.8%, radial parenchyma 19.4%, expanded cells 12.2%, and sieve tubes elements (3.7%). The chemical composition was ash 2.99%, total extractives 19.49% (92% polar extractives), suberin 0.57%, total lignin 25.09%, and polysaccharides 39.90%. The carbohydrates were composed mainly of glucose and xylose (83.7% and 9.7% of all monosaccharides, respectively). Polar (ethanol-water) extracts had a high phenolic content of 324.4 mg of gallic acid equivalents/g (GAE/g) of extract, flavonoids 215.0 mg of catechin equivalents/g (CE/g) extract, and tannins 325.5 mg of catechin equivalents/g (CE/g) extract. The antioxidant activity was low, corresponding to 310.1 mg Trolox equivalents/g extract and an IC50 of 10.59. In view of an integrated potential use, the bark of this E. urophylla hybrid clone is interesting as a source of tannins and a subsequent use for glucose-based applications, while the high-fiber content also allows considering it as a fiber source. [ABSTRACT FROM AUTHOR]

Elsinoë ampelina, the causal agent of grapevine anthracnose, infects all aerial parts of the plant, causing severe grapes production losses. Essential oils, as natural antifungal product, are amongst the most promising natural plant protection alternatives because they are recognized as safe substances and show high antifungal activity against phytopathogenic fungi. The present study aimed to determine Eucalyptus staigeriana essential oil effect in vitro and in vivo against E. ampelina. The essential oil exhibited antifungal activity inhibiting mycelial growth and conidial germination at 0.15 and 1 µL mL−1 concentrations, respectively. Moreover, essential oil application in vivo reduced the disease incidence by 40% and severity by more than 60% in preventive treatment, and in curative treatment, the incidence was reduced by exceeding 30% and severity by more than 80%. The present results indicated that E. staigeriana essential oil could be a natural fungicidal product for controlling anthracnose caused by E. ampelina in grapevines. [ABSTRACT FROM AUTHOR]

In order for a lignocellulosic bioenergy feedstock to be considered sustainable, it must possess a high rate of growth to supply biomass for conversion. Despite the desirability of a fast growth rate for industrial application, it is unclear what effect growth rate has on biomass composition or saccharification. We characterized Klason lignin, glucan, and xylan content with response to growth in Corymbia interspecific F1 hybrid families (HF) and parental species Corymbia torelliana and C. citriodora subspecies variegata and measured the effects on enzymatic hydrolysis from hydrothermally pretreated biomass. Analysis of biomass composition within Corymbia populations found similar amounts of Klason lignin content (19.7-21.3%) among parental and hybrid populations, whereas glucan content was clearly distinguished within C. citriodora subspecies variegata (52%) and HF148 (60%) as compared to other populations (28-38%). Multiple linear regression indicates that biomass composition is significantly impacted by tree size measured at the same age, with Klason lignin content increasing with diameter breast height (DBH) (+0.12% per cm DBH increase), and glucan and xylan typically decreasing per DBH cm increase (-0.7 and -0.3%, respectively). Polysaccharide content within C. citriodora subspecies variegata and HF-148 were not significantly affected by tree size. High-throughput enzymatic saccharification of hydrothermally pretreated biomass found significant differences among Corymbia populations for total glucose production from biomass, with parental Corymbia torelliana and hybrids HF-148 and HF-51 generating the highest amounts of glucose (~180 mg/g biomass, respectively), with HF-51 undergoing the most efficient glucan-to-glucose conversion (74%). Based on growth rate, biomass composition, and further optimization of enzymatic saccharification yield, high production Corymbia hybrid trees are potentially suitable for fast-rotation bioenergy or biomaterial production.

The usage of laccases is a sustainable and environmentally friendly approach to modifying the Kraft lignin structure for use in certain applications. However, the inherent structure of Kraft lignin, as well as that resulting from laccase modification, still presents challenges for fundamental comprehension and successful lignin valorization. In this study, bacterial and fungal laccases were employed to modify eucalypt Kraft lignin. To evaluate the type and range of the chemical and structural changes of laccase-treated lignins, different NMR techniques, including solution 1H and 2D NMR (heteronuclear single quantum correlation (HSQC)), and solid-state 13C NMR, were applied. Size exclusion chromatography and infrared spectroscopy were also used. Interestingly, HSQC analysis showed substantial changes in the oxygenated aliphatic region of lignins, showing an almost complete absence of signals corresponding to side-chains due to laccase depolymerization. Simultaneously, a significant loss of aromatic signals was observed by HSQC and 1H NMR, which was attributed to a deprotonation of the lignin benzenic rings due to polymerization/condensation by laccase reactions. Then, condensed structures, such as α-5′, 5-5′, and 4-O-5′, were detected by HSQC and 13C NMR, supporting the increment in molecular weight, as well as the phenolic content reduction determined in lignins.

Kraft lignin, a side-stream from the pulp and paper industry, can be modified by laccases for the synthesis of high added-value products. This work aims to study different laccase sources, including a bacterial laccase from Streptomyces ipomoeae (SiLA) and a fungal laccase from Myceliophthora thermophila (MtL), for kraft lignin polymerization. To study the influence of some variables in these processes, a central composite design (CCD) with two continuous variables (enzyme concentration and reaction time) and three levels for each variable was used. The prediction of the behavior of the output variables (phenolic content and molecular weight of lignins) were modelled by means of response surface methodology (RSM). Moreover, characterization of lignins was performed by Fourier-transform infrared (FTIR) spectroscopy and different nuclear magnetic resonance (NMR) spectroscopy techniques. In addition, antioxidant activity was also analyzed. Results showed that lignin polymerization (referring to polymerization as lower phenolic content and higher molecular weight) occurred by the action of both laccases. The enzyme concentration was the most influential variable in the lignin polymerization reaction within the range studied for SiLA laccase, while the most influential variable for MtL laccase was the reaction time. FTIR and NMR characterization analysis corroborated lignin polymerization results obtained from the RSM.

Downy mildew (Plasmopara viticola) is the primary disease in viticulture worldwide, and your control requires synthetic fungicides applications to avoid quality and yield loss in the grapevines. However, alternatives to reduce synthetic fungicides are needed to ensure the consumer’s health and the environment. Essential oils (EOs) are amongst the most promising natural plant protection alternatives because of their antifungal properties on several crop diseases. The present study objective was to determine the effect of Eucalyptus staigeriana EO in vitro and in vivo against P. viticola. The EO exhibited the highest activity in vitro, inhibiting 90% of the incidence and severity of disease caused by P. viticola in leaves of grapevines in the greenhouse. In the field (in vivo), treatment with EO could not control the disease; however, treatment with EO in consortium with conventional treatment reduced approximately 50% of the incidence and more than 90% of the severity of downy mildew disease in leaves, decreasing the application of synthetic fungicides by 50%.

Despite the reported allelopathic nature of the Eucalyptus genus, eucalypt leachates have unknown effects on the trophic base of stream green food webs. Eucalypt plantations have increased worldwide, including riparian ecosystems. We aimed to test whether short-term eucalypt leachates might alter water chemistry, periphytic algal biomass and diatoms, and herbivorous invertebrates’ (i.e., scrapers). We studied two oligotrophic and well-preserved headwaters from NW Spain. The experiment followed a before-after control-impact paired (BACIp) design, with weekly sampling before and after eucalypt leaves addition to streams. In the stream with lower discharge, the eucalypt treatments seemed to affect increases in biomass accrual (Chl-a) and diatom assemblages, disfavouring sensitive species (e.g., Eunotia minor and Achnanthidium pyrenaicum). Therefore, the ecological status was reduced from high to good. In the stream with higher discharge, invertebrate assemblages changed with scrapers having their abundances modified in comparison with the control (e.g., Habrophlebia sp. and Elmidae). Results suggest that eucalypt leaves leachates exert toxic effects on periphyton and on diatom and invertebrate assemblages, and this effect might be mediated by discharge. Alterations at the base of stream food webs may compromise their good ecological status. Further studies are necessary to identify whether this toxicity is due to allelopathic processes.

Comments are presented on an article published in October 2020 in Ecology and Evolution ("Predictive ability of a process‐based versus a correlative species distribution model") by Higgins et al. This analyzed natural distributions of Australian eucalypt and acacia species and assessed the adventive range of selected species outside Australia. Unfortunately, inappropriate variables were used with the MaxEnt species distribution model outside Australia, so that large climatically suitable areas in the Northern Hemisphere were not identified. Examples from a previous analysis and from the use of the freely available spatial portal of the Atlas of Living Australia are provided to illustrate how the problem can be overcome. The comparison of methods described in the Higgins et al. paper is worthwhile, and it is hoped that the authors will be able to repeat their analyses using appropriate variables with the correlative model. [ABSTRACT FROM AUTHOR]

Bacterial wilt caused by Ralstonia solanacearum is a serious disease of eucalypt in humid and high temperature areas worldwide. Spreading of the bacterium in the field or to other nurseries occurs mainly by symptomless infected plant material. The use of pathogen‐free propagating material as well as planting of resistant genotypes are currently the only strategies used for disease control. Therefore, a reliable and sensitive method for detection of low titres of R. solanacearum in infected plant tissue is essential for the success of management programmes. In this work, we adapted an efficient intercalating dye‐based real‐time PCR protocol to detect the bacterium in symptomless eucalypt plants as well as to investigate its movement in eucalypt clones CLR172 and CLR371, which exhibit resistant and susceptible phenotypes, respectively. We found that the bacterium translocates acropetally and basipetally in inoculated but symptomless cuttings of the resistant clone, as in cuttings of the susceptible clone displaying symptoms. Nevertheless, a smaller concentration of bacterial DNA was detected in tissues of the resistant clone. Mature biofilms occluding the xylem vessels were present in the susceptible clone whereas only single cells or small aggregates were observed in the resistant clone. This work contributes to improve our knowledge of the colonization process of R. solanacearum in eucalypt clones with different levels of susceptibility and to understand how the defence mechanisms against bacterial wilt in Eucalyptus work. Our findings could aid in the selection of the most resistant eucalypt clones to be used in wilt disease management programmes. [ABSTRACT FROM AUTHOR]

This article presents a method, based on orbital remote sensing, to map the extent of forest plantations in São Paulo State (Southeast Brazil). The proposed method uses the random forest machine learning algorithm available on the Google Earth Engine (GEE) cloud computing platform. We used 30 m annual mosaics derived from Landsat-5 Thematic Mapper (TM) images and from Landsat-8 Operational Land Imager (OLI) images for the 1985 to 1995 and 2013 to 2021 time periods, respectively. These time periods were selected based on the planted areas’ rotation, especially the eucalypt’s short rotation. To classify the forest plantations, green, red, NIR, and MIR spectral bands, NDVI, GNDVI, NDWI, and NBR spectral indices, and vegetation, shade, and soil fractions were used for both sensors. These indices and the fraction images have the advantage of reducing the volume of data to be analyzed and highlighting the forest plantations’ characteristics. In addition, we also generated one mosaic for each fraction image for the TM and OLI datasets by computing the maximum value through the period analyzed, facilitating the classification of areas occupied by forest plantations in the study area. The proposed method allowed us to classify the areas occupied by two forest plantation classes: eucalypt and pine. The results of the proposed method compared with the forest plantation areas extracted from the land use and land cover maps, provided by the MapBiomas product, presented the Kappa values of 0.54 and 0.69 for 1995 and 2020, respectively. In addition, two pilot areas were used to evaluate the classification maps and to monitor the phenological stages of eucalypt and pine plantations, showing the rotation cycle of these plantations. The results are very useful for planning and managing planted forests by commercial companies and can contribute to developing an automatic method to map forest plantations on regional and global scales.

ABSTRACT One of the factors that may affect and limit the production in eucalypt plantations is the attack of defoliating insects. Among those, the brown eucalypt caterpillar, Thyrinteina arnobia (Stoll, 1782) (Lepidoptera: Geometridae), stands out for being the major defoliating pest of Eucalyptus spp. in Brazil. Thus, the present study aimed to investigate the food consumption of T. arnobia, in its native host, guava (Psidium guajava L.), and in the different E. urograndis clones (VE 41, I 144, TP 361 and VCC 865). To assess T. arnobia food consumption, choice and non-choice tests were carried out using the native and the exotic host, alone or in combination. In non-choice tests, it was observed a higher consumption for the VE 41 clone and the native host (guava). The food consumption evaluation in choice tests indicated no food preference of T. arnobia between guava and E. urograndis clones, with the exception for the TP 361 clone, which was significantly less consumed than guava. In choice tests between the different E. urograndis clones, the clone I 144 presented a tendency towards lower food preference, being consumed only after 48 hours. In addition, the leaf consumption was similar between the VE 41, I1 14 e VCC 865 clones. In choice tests using the E. urograndis clones in pairs, the VE 41 clone was more consumed while the I 144 clone was less consumed when compared to the TP 361 clone. The obtained results provide basic information for the indication of eucalypt clones, and the understanding of the interaction and ecological relationships, assisting in the development of Forest Integrated Pest Management (Forest IPM) programs for the control of T. arnobia.

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In food-productive river basins, ecosystems reliant on natural flows are affected by climate change and water removal. One such example is Australia's Murray-Darling Basin (MDB), to which the ecologically important black box tree Eucalyptus largiflorens (Myrtaceae) is unique. Little is known about its mineral nutrition and response to flooding. A field study conducted at Hattah Kulkyne National Park on the MDB examined nutrient and Al distribution in mature and young foliage of trees whose status varied with respect to the presence of surface floodwaters. Black box is also of interest due to emerging evidence of its capacity to accumulate high foliar salt concentrations. Here, cryo scanning electron microscopy alone (SEM), combined with energy dispersive spectroscopy (SEM-EDS) and X-ray fluorescence (XRF) spectroscopy were applied to evaluate leaf anatomy and elemental patterns at the cellular and whole-leaf levels. Variation in whole-leaf elemental levels across flooded and dry trees aligned with known nutritional fluctuations in this drought-tolerant species reliant on occasional infrequent flooding. The microprobe data provide evidence of drought tolerance by demonstrating that extended conditions of lack of water to trees do not elicit leaf anatomical changes nor changes to leaf cellular storage of these elements. Foliar Na concentrations of ~2000-6000 mg kg-1 DW were found co-localised with Cl in mesophyll and dermal cells of young and mature leaves, suggesting vacuolar salt disposal as a detoxification strategy. Black box, the iconic floodplain eucalypt unique to Australia's Murray-Darling Basin, is affected by anthropogenic activities, yet knowledge about its environmental interactions is limited. Little is understood of its adaptation to drier conditions well away from watercourses. This study revealed similar leaf structure and nutrient distribution in both flooded trees and those that received very little water, with indication of possible species-wide salt tolerance. Insights were gained into key aspects of black box tolerance of dry and saline conditions. [ABSTRACT FROM AUTHOR]

Abstract Cryptococcosis is a fungal infection caused by members of the Cryptococcus gattii and C. neoformans species complexes. The C. gattii species complex has a strong environmental association with eucalypt hollows (particularly Eucalyptus camaldulensis), which may present a source of infection. It remains unclear whether a specific mycobiome is required to support its environmental survival and growth. Conventional detection of environmental Cryptococcus spp. involves culture on differential media, such as Guizotia abyssinica seed agar. Next‐generation sequencing (NGS)‐based culture‐independent identification aids in contextualising these species in the environmental mycobiome. Samples from 23 Australian tree hollows were subjected to both culture‐ and amplicon‐based metagenomic analysis to characterize the mycobiome and assess relationships between Cryptococcus spp. and other fungal taxa. The most abundant genera detected were Coniochaeta, Aspergillus, and Penicillium, all being commonly isolated from decaying wood. There was no correlation between the presence of Cryptococcus spp. in a tree hollow and the presence of any other fungal genus. Some differences in the abundance of numerous taxa were noted in a differential heat tree comparing samples with or without Cryptococcus‐NGS reads. The study expanded the known environmental niche of the C. gattii and C. neoformans species complexes in Australia with detections from a further five tree species. Discrepancies between the detection of Cryptococcus spp. using culture or NGS suggest that neither is superior per se and that, rather, these methodologies are complementary. The inherent biases of amplicon‐based metagenomics require cautious interpretation of data through consideration of its biological relevance.

Abstract Conservation management often uses information on genetic population structure to assess the importance of local provenancing for ecological restoration and reintroduction programs. For species that do not exhibit complete reproductive isolation, the estimation of population genetic parameters may be influenced by the extent of admixture. Therefore, to avoid perverse outcomes for conservation, genetically informed management strategies must determine whether hybridization between species is relevant, and the extent to which observed population genetic patterns are shaped by interspecific versus intraspecific gene flow. We used genotyping by sequencing to identify over 2,400 informative single nucleotide polymorphisms across 18 populations of Eucalyptus regnans F. Muell., a foundation tree species of montane forests in south‐eastern Australia. We used these data to determine the extent of hybridization with another species, Eucalyptus obliqua L'Hér., and investigate how admixture influences genetic diversity parameters, by estimating metrics of genetic diversity and examining population genetic structure in datasets with and without admixed individuals. We found hybrid individuals at all sites and two highly introgressed populations. Hybrid individuals were not distributed evenly across environmental gradients, with logistic regression identifying hybrids as being associated with temperature. Removal of hybrids resulted in increases in genetic differentiation (FST), expected heterozygosity, observed heterozygosity and the inbreeding coefficient, and different patterns of isolation by distance. After removal of hybrids and introgressed populations, mountain ash showed very little population genetic structure, with a small effect of isolation by distance, and very low global FST(0.03). Our study shows that, in plants, decisions around provenancing of individuals for restoration depend on knowledge of whether hybridization is influencing population genetic structure. For species in which most genetic variation is held within populations, there may be little benefit in planning conservation strategies around environmental adaptation of seed sources. The possibility for adaptive introgression may also be relevant when species regularly hybridize.

Understanding the effects of logging and fire on forest soil communities is integral to our knowledge of forest ecology and effective resource management. The resulting changes in soil biota have substantial impacts on forest succession and associated ecosystem processes. We quantified bacterial and fungal abundance, diversity and community composition across a logging and burn severity gradient, approximately one month after fire, in temperate wet eucalypt forests in Tasmania, Australia. Using amplicon sequencing and real‐time quantitative PCR of the bacterial 16S rRNA gene and fungal ITS1 region, we demonstrate that (i) burn severity is a strong driver of soil microbial community composition, (ii) logging and high severity burning substantially reduce the biomass and diversity of soil bacteria and fungi, and (iii) the impacts of logging and burning on soil microbial communities are largely restricted to the top 10 cm of soil, with weak impacts on the subsoil. The impacts of disturbance on microbial community composition are greater than the effects of site‐to‐site edaphic differences. Fire also drives more divergence in community composition than logging alone. Key microbial taxa driving differences in severely burnt soils include bacterial genera implicated in plant‐growth promotion and producing antifungal compounds as well as saprotrophic fungi that are also capable of forming ectomycorrhizal associations. Our research suggests that low‐moderate severity burns are important for maintaining diversity and biomass in soil microbial communities but having a range of burn severities across a site contributes to the overall diversity of habitat conditions providing for both microbial and plant diversity. [ABSTRACT FROM AUTHOR]

Erwinia psidii is a gram‐negative bacterium that threatens both guava and eucalypt plantations in several countries. Despite the economic importance of both crops, nothing is currently known about the molecular mechanisms underlying E. psidii pathogenicity and, consequently, how it evolved to infect Eucalyptus species besides its presumed native host Psidium guajava. In this study, we predicted putative type III secretion system effectors that may play important roles during plant–E. psidii interactions and conducted effector structure and phylogenetic analyses to gain important insights into their function and evolution. For that, the whole genomes of four E. psidii strains that exhibit differential aggressiveness towards eucalypt clones were sequenced and their effector repertoires predicted based on sequence identity with known effectors of the model phytopathogen Erwinia amylovora. Only proteins sharing significant sequence identity with the DspE and Eop1 effectors were found. Here, it is shown that these two E. psidii effectors retain all structural characteristics of their corresponding protein superfamilies, but exhibit allelic variations that are consistent with the observed aggressiveness differences between strains. Phylogenetic analyses revealed that whereas E. psidii housekeeping gene sequences are more closely related to those from Erwinia tracheiphila, the effector (either nucleotide or amino acid) sequences are more closely related to their Pantoea agglomerans counterparts, suggesting that dspE and eop1 were both acquired through horizontal gene transfer from the latter bacterial species. The results of this study provide important insights on E. psidii pathogenicity and set the stage for future effector functional studies. [ABSTRACT FROM AUTHOR]

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The chemical and anatomical properties of Eucalyptus globulus stumps barks collected from fresh stumps (SB) and from industrial stumps bark piles (ISB) were determined. The stump bark showed similar anatomical structure to that of the stem bark, however with abundant prismatic crystals in the axial parenchyma cells. Stumps barks (ISB) presented a great amount of ashes (19.2%) that were incorporated during forest and mill processing, and lower content in extractives (4.1%), lignin (18.5%) and polysaccharides (48.5%). The non-polar (DCM) extracts were composed essentially by triterpenoids, fatty acids (C8 to C28), phytosterols (sterols and steroid ketones) and fatty alcohols (C15 to C28). The polar extracts (ethanol and water) were rich in phenolic compounds, condensed tannins and flavonoids, with higher values for the ethanol extracts and for SB. The antioxidant activity of ethanol extracts from SB was higher although only moderate (IC50 6.8). The lignin monomeric composition (H:G:S) was similar in SB (1:12:45) and in ISB (1:9:26). Sugar-derived compounds formed by Py-GC/MS included more low molecular compounds in ISB than in SB (45.5% vs.20.3%) indicative of a more degraded structure. [ABSTRACT FROM AUTHOR]