Populus Deltoides Research Articles

In the tripartite combination ozone-poplar-Chrysomela populi, the pollutant alters the plant-insect interaction via primary metabolites of foliage

Ozone (O3)-induced metabolic changes in leaves are relevant and may have several ecological significances. Here, variations in foliar chemistry of two poplar clones (Populus deltoides × maximowiczii, Eridano, and P. × euramericana, I-214) under a chronic O3 treatment (80 ppb, 5 h d−1 for 10 consecutive days) were investigated. The aim was to elucidate if leaf age and/or O3-sensitivity (considering Eridano and I-214 as O3-sensitive and O3-resistant, respectively) can affect suitability of poplar foliage for Chrysomela populi L. (Coleoptera Chrysomelidae), in terms of palatability. Comparing controls, only low amino acid (AA) contents were reported in Eridano [about 3- and 4-fold in mature and young leaves (ML and YL, respectively)], and all the investigated primary metabolites [i.e. water soluble carbohydrates (WSC), proteins (Prot) and AA] were higher in YL than in ML of I-214 (+23, +54 and + 20%, respectively). Ozone increased WSC only in YL of Eridano (+24%, i.e. highest values among samples; O3 effects are always reported comparing O3-treated plants with the related controls). A concomitant decrease of Prot was observed in both ML and YL of Eridano, while only in YL of I-214 (−41, −45 and −51%, respectively). In addition, O3 decreased AA in YL of Eridano and in ML of I-214 (−40 and −14%, respectively). Comparing plants maintained under charcoal-filtered air, total ascorbate (Asc) was lower in Eridano in both ML and YL (around −22%), and abscisic acid (ABA) was similar between clones; furthermore, higher levels of Asc were reported in YL than in ML of Eridano (+19%). Ozone increased Asc and ABA (about 2- and 3-fold, respectively) in both ML and YL of Eridano, as well as ABA in YL of I-214 (about 2-fold). Comparing leaves maintained under charcoal-filtered air, the choice feeding test showed that the 2nd instar larvae preferred YL, and the quantity of YL consumed was 9 and 4-fold higher than ML in Eridano and I-214, respectively. Comparing leaves exposed to O3-treatment, a significant feeding preference for YL disks was also observed, regardless of the clone. The no-choice feeding test showed that larval growth was slightly higher on untreated YL than on untreated ML (+19 and + 10% in Eridano and I-214, respectively). The body mass of larvae fed with O3-treated YL was also significantly higher than that of larvae fed with untreated YL (3- and 2-fold in Eridano and I-214). This study highlights that realistic O3 concentrations can significantly impact the host/insect interactions, a phenomenon dependent on leaf age and O3-sensitivity of the host.

Combined transcriptome and proteome analysis provides insights into anthocyanin accumulation in the leaves of red-leaved poplars.

Anthocyanin was highly accumulated in the leaves of red-leaved poplars; Many structural genes involved in anthocyanin synthesis were significantly up-regulated in 'Quanhong' and 'Xuanhong'; TTG2, HYH, and HY5 may be directly involved in the regulation of anthocyanin synthesis in both red-leaved poplars. The red-leaved poplar cultivars 'Quanhong' and 'Xuanhong' are bud mutations of Populus deltoides cv. 'Zhonglin 2025'. These cultivars are valued for their beautiful shape, lack of flying catkins, and ornamental leaf colors. However, the understanding of the molecular mechanism of anthocyanin accumulation in the leaves of red-leaved poplars is still unclear. Here, we profiled the changes of pigment content, transcriptome and proteome expression in the leaves of three poplar cultivars and the results showed that the ratios of anthocyanin to total chlorophyll in both red-leaved poplars were higher than that in 'Zhonglin 2025', indicating that the anthocyanin was highly accumulated in the leaves of red-leaved poplars. Based on the results of combined transcriptome and proteome analysis, 15 and 11 differentially expressed genes/proteins involved in anthocyanin synthesis were screened in 'Quanhong' and 'Xuanhong', respectively, indicating that the two red-leaved poplar cultivars have slightly different patterns of regulating anthocyanin biosynthesis. Among the 120 transcription factors, 3 (HY5, HYH, and TTG2), may be directly involved in the regulation of anthocyanin synthesis in both red-leaved poplars. This study screens the candidate genes involved in anthocyanin accumulation in the leaves of red-leaved poplars and lays a foundation for further exploring the molecular mechanism of leaf red coloration in red-leaved poplars.

Foliar Application of Salicylic Acid Improves Water Stress Tolerance in Conocarpus erectus L. and Populus deltoides L. Saplings: Evidence from Morphological, Physiological, and Biochemical Changes.

Reforestation efforts are being challenged as water stress is hampering the sapling growth and survival in arid to semiarid regions. A controlled experiment was conducted to evaluate the effect of foliar application of salicylic acid (SA) on water stress tolerance of Conocarpus erectus and Populus deltoides. Saplings were watered at 90%, 60%, and 30% of field capacity (FC), and half of the saplings under 60% and 30% FC were sprayed with 1.0 mM SA. Results indicated that dry weight production decreased significantly in Populus deltoides under both water deficit conditions, and leaf gas exchange parameters decreased significantly in both the species under both soil water deficit conditions. Foliar application of SA resulted in a significant increase in leaf gas exchange parameters, and compatible solutes, thereby increasing the dry weight production in both of the species under soil water deficit. Oxidative stress (hydrogen peroxide and superoxide anions) increased under soil water deficit and decreased after the foliar application of SA and was parallel to the increased antioxidant enzymes activity (superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase). Therefore, it can be concluded that foliar application of 1.0 mM SA can significantly improve the water stress tolerance in both species, however, positive impacts of SA application were higher in Conocarpus erectus due to improved photosynthetic capacity and increased antioxidant enzyme activity.

Morphological and physiological plasticity response to low nitrogen stress in black cottonwood (Populus deltoides Marsh.)

It is important to evaluate nitrogen use efficiency and nitrogen tolerance of trees in order to improve their productivity. In this study, both were evaluated for 338 Populus deltoides genotypes from six provenances. The plants were cultured under normal nitrogen (750 μM NH4NO3) and low nitrogen (5 μM NH4NO3) conditions for 3 months. Growth, chlorophyll content and glutamine synthetase activity of each genotype were measured. Under low nitrogen, heights, ground diameter, leaf area, leaf and root biomass, and chlorophyll contents were significantly lower than those under normal nitrogen level. Correlation analysis showed that nutrient distribution changed under different nitrogen treatments. There was a negative correlation between leaf traits and root biomass under normal nitrogen level, however, the correlation became positive in low nitrogen treatment. Moreover, with the decrease of nitrogen level, the negative correlation between leaf morphology and chlorophyll levels became weakened. The growth of the genotypes under the two treatments was evaluated by combining principal component analysis with a fuzzy mathematical membership function; the results showed that leaf traits accounted for a large proportion of the variation in the evaluation model. According to the results of comprehensive evaluation of plants under the two treatments, the 338 P. deltoides genotypes could be divided into nine categories, with wide genotypic diversity in nitrogen use efficiency and low nitrogen tolerance. As a result, 26 N-efficient genotypes and 24 N-inefficient genotypes were selected. By comparative analysis of their morphological and physiological traits under the two treatments, leaf traits could be significant indicators for nitrogen use efficiency and nitrogen tolerance, which is of considerable significance for breeding poplar varieties with high nitrogen use efficiencies.

Diverse Understory Vegetation Alleviates Nitrogen Competition with Crop Trees in Poplar Plantations

Understory vegetation plays a crucial role in nutrient turnover and cycling in plantations, but it also competes for nutrients with crop trees when only a single species is present due to its specific nutrient requirements. However, it remains unclear whether this competition can be alleviated when the species richness of understory vegetation increases. In this study, we tested different gradients of understory vegetation species richness, including understory vegetation removal (UR), the retention of a single main understory vegetation species (RS), and the retention of natural diverse understory vegetation (RD) as part of a poplar (Populus deltoides ‘Nanlin-3804′) plantation, to study their effects on poplar growth, and to evaluate nitrogen (N) usage and how this was affected by the interactions between the poplar and understory vegetation. The results showed a generally lower periodic growth, and a significant decline in the foliar chlorophyll content and glutamine synthetase activity of poplar under treatment with RS and RD compared to those under UR treatment conducted in July 2019, which clearly indicated N competition between the understory vegetation and poplar trees. However, no significant difference was detected in the foliar chlorophyll content and glutamine synthetase activity of poplar under RD and RS treatment; only the nitrate reductase activity in poplar leaves under RD treatment declined significantly, by 22.25%, in June 2019. On the contrary, the diameter at breast height (DBH) of the poplar under RD treatment showed an increase of 34.69% from July to August 2019, compared with that under RS treatment. Furthermore, the increase in the species richness of understory vegetation resulted in an increase in the δ15N values in the poplar leaves, which was strongly regulated by the NH4+-N pool in the 10–20 cm soil layer, indicating the effective coordination of N utilization between poplar and understory vegetation when diversified understory plant species were present. These findings demonstrate the essential role of understory vegetation species diversity in alleviating N competition with crop trees, and provide guidance for understory vegetation management in poplar plantations.

Biochemical and Gene Expression Analyses in Different Poplar Clones: The Selection Tools for Afforestation of Halomorphic Environments

Halomorphic soils cover a significant area in the Vojvodina region and represent ecological and economic challenges for agricultural and forestry sectors. In this study, four economically important Serbian poplar clones were compared according to their biochemical and transcriptomic responses towards mild and severe salt stress to select the most tolerant clones for afforestation of halomorphic soils. Three prospective clones of Populus deltoides (Bora-B229, Antonije-182/81 and PE19/66) and one of hybrid genetic background P. nigraxP. deltoides, e.g., P. x euramericana (Pannonia-M1) were hydroponically subjected to NaCl as a salt stress agent in a concentration range from 150 mM to 450 mM. Plant responses were measured at different time periods in the leaves. Biochemical response of poplar clones to salt stress was estimated by tracking several parameters such as different radical scavenging capacities (estimated by DPPH, FRAP and ABTS assays), accumulation of total phenolic content and flavonoids. Furthermore, accumulation of two osmolytes, glycine betaine and proline, were quantified. The genetic difference of those clones has been already shown by single nucleotide polymorphisms (SNPs) but this paper emphasized their differences regarding biochemical and transcriptomic salt stress responses. Five candidate genes, two putative poplar homologues of GRAS family TFs (PtGRAS17 and PtGRAS16), PtDREB2 of DREB family TFs and two abiotic stress-inducible genes (PtP5SC1, PtSOS1), were examined for their expression profiles. Results show that most salt stress-responsive genes were induced in clones M1 and PE19/66, thus showing they can tolerate salt environments with high concentrations and could be efficient in phytoremediation of salt environments. Clone M1 and PE19/66 has ABA-dependent mechanisms expressing the PtP5CS1 gene while clone 182/81 could regulate the expression of the same gene by ABA-independent pathway. To improve salt tolerance in poplar, two putative GRAS/SCL TFs and PtDREB2 gene seem to be promising candidates for genetic engineering of salt-tolerant poplar clones.

Radial variation studies on wood properties of Populus deltoides parents and their hybrids

The radial variation and the genetic variation of wood properties between the parents and offspring of Populus deltoides were studied in this work. The chemical composition, density, and anatomical characteristics of Populus deltoides cl. ‘Danhong’ and its offspring exhibited the phenomenon of transgressive segregation. The chemical compositions of the parents and offspring were decreased in several attributes (benzene alcohol extract, hemicelluloses, lignin) with the increase of the cambial age. Moreover, the fibre length, fibre width, ratio of fibre length to width, and wall thickness to lumen ratio of parents and offspring were increased with cambial age. In addition, the densities of parents and offspring were increased with the increase of cambial age. There were significant differences in wood properties among Populus deltoides and its hybrids. These results indicated that Populus deltoides cl. ‘Danhong’ could be considered as pulp material and Populus deltoides cl. ‘Nanyang’ as building material. According to the radial variation rule of each material character, the rotation cutting period can be selected as years 7 or 8.

Determining elastic constants of poplar wood (Populus deltoides) by ultrasonic waves and its application in the finite element analysis

ABSTRACT In simulation of wood mechanical behaviors, it is imperative to define elastic engineering parameters of the wood (three Young’s moduli, three shear moduli and six Poisson’s ratios). As regards, the determination of a set of nine independent elastic constants of wood by the experimental method is expensive and laborious and requires several specimens and test equipment and the literature is very rare and has a wide range in data. In this study, elastic engineering parameters of poplar wood (Populus deltoides) were determined by applying the ultrasonic waves and their first-ever application as input data in simulation of mechanical behavior of the poplar wood. Ultrasonic velocity measurements give a chance for the direct determination of the all orthotropic elastic constants using only little small stresses to the wood material. The commercial finite element program ABAQUSTM software package was used to model and analyze as linear orthotropic elastic materials. For validating the applicability and better and more accurate evaluation of engineering parameters were determined by ultrasonic wave propagation in simulation, both three-point bending and uniaxial tensile tests were examined. The ultrasonic technique for determination of elastic engineering parameters of poplar wood, as input data in the finite element method, leads to a very close correlation with the experiment results, which turns out that these data are reliable and applicable for the simulation of wood behaviors.

Punctuated decadal morphodynamics and coupled vegetation succession along a nontidal, wave-dominated Great Lakes barrier spit, Gull Point, Lake Erie, U.S.A.

The Presque Isle Peninsula is a compound barrier-spit system perched atop a recessional moraine along Lake Erie’s southeastern coast. Its distal terminus, Gull Point, has grown to an extent of around 0.6 km2 since the early 1900s, promoted by beach nourishment along the peninsula proper and later influenced by a change in local hydrodynamic regime following breakwater installation near the attachment point. This coastal setting has set the stage for an analysis of ridge landform- and vegetation-succession dynamics using historical aerial images, a series of high-resolution LiDAR datasets, transect/quadrat surveys of vegetation, and increment core dates of tree cohorts on dune ridges separated by swales and lagoons. The general evolutionary model is one of punctuated landform growth to the east by lateral accretion, interspersed with erosional events and ridge recurving towards the backbarrier. Eastern cottonwood (Populus deltoides), with its minimally provisioned wind- and water-dispersed seeds, colonizes the margins of newly deposited sand ridges as discrete cohorts, and dominates the tree stratum of Gull Point. These cohorts are increasingly mature moving from distal to proximal zones, and consistently reflect the temporal sequence of ridge morphology. Vegetation communities, representing a primary successional chronosequence, are delineated into four phases extending back to the 1950s, which are roughly demarcated by erosional ridgelines of topographic prominence, revealing a tight coupling of lake-level trends, geomorphology, and vegetation dynamics. This provides coastal researchers with a means of understanding landform-age relationships across structurally complex strand areas for which age-relationships cannot be ascertained by aerial photographic records alone.

Effects of growth rate of eastern poplar trees on the chemical and morphological characteristics of wood fibers

Attempts are underway to speed up timber production using genetic improvement and enhanced management practices. However, the impacts of possible morphological and chemical changes on the properties of secondary wood products are less studied. This research thus studied the relationship of tree-ring widths of eastern poplar trees (Populus deltoides Bartr.) and the morphological and chemical characteristics of the wood fibers. Cellulose, lignin, ash, and extractives contents were determined according to the Technical Association of Pulp and Paper Industry standards. Accordingly, the mean values of the various parameters measured, such as the fiber length and diameter, the diameter of the cell cavity, and the cell wall thickness along with functionality parameters such as Runkel, slenderness, and flexibility ratio, and the amounts of cellulose, lignin, extractives, and ash contents were determined. As a result, statistical analysis indicated significant correlations between tree-ring width and length and diameter of the fiber, cell cavity, Runkel ratio, cell wall thickness, cellulose content and wood density. On the contrary, there were no significant correlations between tree-ring width and slenderness and flexibility ratios, lignin, ash, and extractives contents. The investigation on the radial variation of wood properties showed from the pith to the bark, fiber length and diameter, cell wall thickness, cellulose, and density increased, and cell cavity, Runkel ratio, ash, extractives, and lignin contents decreased. Overall, increases in tree-ring width of eastern poplar improved wood quality, as raw material, for manufacturing of the most common secondary products in the wood industry, including paper and fiberboard with wide-ranging wood applications.

Interconversion between methoxylated, hydroxylated and sulfated metabolites of PCB 3 in whole poplar plants

Methoxylated polychlorinated biphenyls (MeO-PCBs) are overlooked metabolites of PCBs. In general, they are more toxic to plants than their parent congeners. However, information on the fate of MeO-PCBs and the relationship between methoxylated, hydroxylated and sulfated metabolites of PCBs in plants is scarce. In this work, poplar plants (Populus deltoides × nigra, DN34) were hydroponically and separately exposed to 4′-methoxy-4-monochlorobiphenyl (4′-MeO-PCB 3) and 4′-PCB 3 sulfate for 10 days to investigate the uptake, translocation and metabolism of MeO-PCBs and the relationship between methoxy-PCBs, hydroxyl-PCBs and PCB sulfates within plants. Results showed that 4′-MeO-PCB 3 and 4′-PCB 3 sulfate were taken up by the roots of poplar plants and translocated from roots to shoots and leaves. 4′-OH-PCB 3 and 4′-PCB 3 sulfate were identified as the hydroxylated metabolite and sulfate metabolite of 4′-MeO-PCB 3 in poplar, respectively. In the backward reaction, 4′-OH-PCB 3 and 4′-MeO-PCB 3 were found as metabolites of 4′-PCB 3 sulfate. For exposure groups, the yields of 4′-OH-PCB 3 produced from 4′-MeO-PCB 3 and 4′-PCB 3 sulfate were 1.29% and 0.13% respectively. The yield of 4′-PCB 3 sulfate which originated from 4′-MeO-PCB 3 in wood and root samples of exposure groups was only 0.02%. Only 0.04% of the initial mass of 4′-PCB 3 sulfate was transformed to 4′-MeO-PCB 3 in the exposure groups. The sulfation yield of 4′-OH-PCB 3 was higher than hydrolysis yield of 4′-PCB 3 sulfate, indicating that formation of PCB sulfates was predominant over the reverse reaction, the formation of hydroxy-PCBs. These results provide new perspective on the transport, metabolism, and fate of MeO-PCBs, and also help to better understand sources of OH-PCBs and PCB sulfates in the environment. This study provides the first evidence of interconversion of sulfate metabolites from methoxy-PCBs and methoxy-PCBs from PCB sulfates.

Long-term effects of phytoextraction by a poplar clone on the concentration, fractionation, and transportation of heavy metals in mine tailings.

Mine tailings are one of main causes of diffused heavy metal pollution since the heavy metals in there may acquire mobility. The current knowledge of the processes at work in long-term phytoremediation by woody species remains insufficient. Through a 4-year field study, we evaluated the phytoextraction efficiency of Populus deltoides CL. 'Xianglin 90' grown on a mine tailing co-polluted by Cd, Cu, Cr, Ni, Pb, and Zn. The concentrations of Cd, Cu, Ni, Pb, and Zn in the rhizospheric soil were reduced by amounts ranging from 12.86 to 42.19% during the study period. Bioconcentration factors and translocation factors showed that the accumulation of Cd and Zn occurring in the shoots was the most effective. Combined with the considerable biomass produced by poplar, the extracted amounts of Cd and Zn could reach 0.61 g and 10.66 g plant-1, respectively, in which the shoots account for 77.3% (Cd) and 89.0% (Zn) of the overall extraction amounts. Acid-soluble Cd and Zn increased by 5.49% and 4.29%, respectively, in the rhizosphere compared to the bulk soil, indicating that poplar enhanced the mobility of Cd and Zn in the rhizosphere, which explained its ability for bioaccumulation and root-shoot translocation. Moreover, calculated time required to address the issue of Cd and Zn pollution was theoretically shortened by more than half from 2015 to 2019. This study brings new insights into the long-term effects of phytoextraction on the concentration, fractionation, and transportation of heavy metals and confirms the potential of poplar as a Cd and Zn remediation species.

Effect of variations in phytochemicals of Populus nigra and Populus deltoids on life history attributes of Chaitophorus leucomelas (Koch, 1854) in the littoral (Zéralda) and the sublittoral (Soumâa) of Algeria

The aphid Chaitophorus leucomelas (Koch, 1854) is one of the most im-portant pests of poplar (Populus spp.) in Algeria. In the present study, water content in leaves and phytochemical analysis of two poplar species (P. nigra and P. deltoids) were carried out to assess their trophic impact on life-history traits of C. leucomelas. The study was conducted in two areas located north of Algeria during the period printano-summer. The results showed that each metabolite fluctuated at the expense of physiological variations in the plant depending on its reaction to the study area. Soluble carbohydrates gradually decreased over the two study seasons. The concentration of proline was higher for P. deltoids in Zeralda comparing to Soumâa. However, the flavo-noids showed close values. Interestingly, Relative water content and soluble carbohydrates had a positive effect on both aphid weight and lipidic ener-getic reserves on P. nigra, but on P. deltoids only carbohydrate content was marginally related to soluble carbohydrates.

Xylem transport of root-derived CO2 caused a substantial underestimation of belowground respiration during a growing season.

Previous research has indicated that a potentially large portion of root-respired CO2 can move internally through tree xylem, but these reports are relatively scarce and have generally been limited to short observations. Our main objective was to provide a continuous estimate of the quantity and variability of root-respired CO2 that moves either internally through the xylem (FT ) or externally through the soil to the atmosphere (FS ) over most of a growing season. Nine trees were measured in a Populus deltoides stand for 129days from early June to mid-October. We calculated FT as the product of sap flow and dissolved [CO2 ] in the xylem (i.e., [CO2 *]) and calculated FS using the [CO2 ] gradient method. During the study, stem and soil CO2 concentrations, temperature, and sap flow were measured continuously. We determined that FT accounted for 33% of daily total belowground CO2 flux (i.e., FS +FT ; FB ) during our observation period that spanned most of a growing season. Cumulative daily FT was lower than FS 74% of the time, equivalent to FS 26% of the time, and never exceeded FS . One-third of the total CO2 released by belowground respiration over most of the growing season in this forest stand followed the FT pathway rather than diffusing into the soil. The magnitude of FT indicates that measurements of FS alone substantially underestimate total belowground respiration in some forest ecosystems by systematically underestimating belowground autotrophic respiration. The variability in FT observed during the growing season demonstrated the importance of making long-term, high-frequency measurements of different flux pathways to better understand physiological and ecological processes and their implications to global change.

Soil Fungal Community Structure and Functional Diversity in a Copper Tailing Dam and Its Surrounding Areas

Soil fungal communities are reconstructed under heavy metal stress. This study was conducted to explore the structural and functional diversity of soil fungal communities under different land-use patterns, namely grassland and farmland, in 15-year-old or 10-year-old poplar plantations (Populus deltoides cv. 'zhonghuahongye') near the Shibahe copper tailing dam and the surrounding area, located in Yuanqu County, Shanxi. The results indicated that the abundance and diversity of fungal communities were the highest in the 15-year-old poplar plantation and lowest in the grassland on the tailing dam. The dominant fungal groups in the study area were Ascomycota, Basidiomycota, and Mortierellomycota. The Ascomycota members were the most abundant at all four sampling sites, reaching 92.92% of the fungal community in the grassland on the tailing dam. The highest functional diversity of carbon utilization was found in the soil fungal communities of the 15-year-old poplar plantations; moreover, the diversity in the grassland on the tailing dam was significantly higher than that in the farmland and in the 10-year-old poplar plantation. Meanwhile, we also observed the highest glucoside carbon source utilization efficiency in the grassland. Notably, the correlation analysis revealed that Ascomycota was significantly correlated with the utilization efficiency of the glucoside carbon source in our study area. Moreover, the soil total nitrogen content, but not the soil heavy metal content, was significantly correlated with the abundance of the soil fungal community. There were significant correlations between the cadmium and arsenic contents and the soil fungal community diversity indices. Our results indicated that the soil fungal communities were more influenced by soil fertility and land use than by the soil heavy metal content. This study underlies the application of soil fungal communities in soil remediation of heavy metal-contaminated areas.

Relación entre el Módulo de Elasticidad Global y Local en Elementos Estructurales de Populus Deltoides ‘Australiano 129/60’ y ‘Stoneville 67’ Cultivados en Argentina

En este trabajo se compara el valor del módulo de elasticidad local obtenido experimentalmente con el determinado a partir del módulo de elasticidad global de acuerdo a tres criterios reconocidos internacionalmente (UNE-EN 384 2016, INTI-CIRSOC 2016 y Danzler et al. 2008). El programa experimental se desarrolló de acuerdo a normas europeas sobre 396 elementos estructurales de madera aserrada de Populus deltoides, clones ‘Australiano 129/60’ y ‘Stoneville 67’, cultivados en el delta del río Paraná en Argentina. Se confirmó la alta correlación entre el módulo de elasticidad local y el módulo de elasticidad global. Se constató la incidencia que, en la relación entre ambos módulos, tiene la exigencia normativa de ubicar los mayores defectos en el tercio central al ensayar las piezas. La determinación a partir del módulo de elasticidad global presentó resultados menores a los experimentales con una aproximación superior al 95%.

Impact of Enzootic Plague on a Population of Mexican Woodrats

Photo 1: Our controlled study of plague utilized capture–recapture to estimate survival rates of Mexican woodrats (Neotoma mexicana) in four groups comprising all combinations of vaccination, vector control, and no treatment. Photo credit: D. Biggins. Photo 2: Our study area in the Colorado foothills had many woodrat nests in shrub patches (especially three-leaf sumac, Rhus trilobata, whose leaves turned orange in fall (foreground and right side of photograph). A few nests were in cavities of cottonwoods (Populus deltoides; center). Photo credit : D. Biggins. Photo 3: Mexican woodrats are industrious nest-builders. Panel A shows a large stick nest (~ 1 m high, estimated volume 510 liters, ranked 11th largest of 139 stick nests measured) in a hawthorn (Crataegus succulenta) and sumac shrub patch. Some nests were in rock crevices (B). Photo credit : D. Biggins (A) and S. Ramakrishnan (B). Photo 4: Woodrats also constructed nests by modifying abandoned magpie (Pica hudsonia) nests (panels A and B). We infused woodrat nests on treated plots with deltamethrin dust to control vector fleas. Photo credit: D. Biggins. Photo 5: We trapped woodrats in wire mesh traps (A) and handled them under isoflurane anesthesia to collect blood samples (B), comb fleas, and take measurements, and to vaccinate a subsample of them with an experimental plague vaccine. We combed one or more fleas from 51% of the woodrats on non-dusted plots compared to a flea prevalence of 5% on dusted plots. Photo credit: S. Ramakrishnan. These photographs illustrate the article “Enzootic plague reduces survival of Mexican woodrats (Neotoma mexicana) in Colorado” by Biggins, D. E. S. Ramakrishnan, T. E. Rocke, J. L. Williamson, and J. Wimsatt published in Ecosphere. https://doi.org/10.1002/ecs2.3371.

Growth performance of Ganoderma lucidum using billet method in Garhwal Himalaya, India.

Medicinal mushrooms have been used in various treatments from a very long time, among which, Ganoderma lucidum is one of the most important medicinal mushroom. It is cultivated worldwide to meet its ever-increasing demand in the market. It is generally cultivated by bed log (Sawdust) and wood log (billet) method. This study was an attempt to observe the growth performance of G. lucidum on poplar billets (Populus deltoides) in the Sherpur Village (Dehradun) and Manjgaun village (Tehri Garhwal) of Garhwal Himalaya, India. The farmers’ field with empty house/ rooms having proper growing conditions especially humidity and light were used for the cultivation of G. lucidum. The G. lucidum spawn was inoculated in poplar wood billets and these billets were installed in well prepared soil. The results demonstrated that cropping cycle of G. lucidum was shorter (132–136 days) in Sherpur Village (Dehradun) as compared to Manjgaun village (141–145 days) in Tehri Garhwal. Further the results also revealed that yield was decreased in the subsequent flushes. In Village Sherpur, the fruiting bodies of G. lucidum were harvested between 64-66 days, 100-101 days and 135-136 days during first, second and third flush after the installation of billets, respectively. However; in village Manjgaun, the fruiting bodies of G. lucidum were harvested between 69 and 71 days, 107-108 days and 144-145 days in first, second and third after the installation of billets respectively. Warmer temperature in Village Sherpur resulted in the early emergence and development of the fruiting bodies as compared to village Manjgaun where pinhead and fruiting body development was delayed due to the lower temperature during cropping cycle.

Comparison of cadmium accumulation in upright and leaning poplar trees

Poplar 69 (Populus deltoides Bartr. cv. ‘Lux’ (I-69/55)) was chosen for a pot experiment to study the growth and the extraction of Cd from soil to various parts of the one-year-old trees growing in upright and artificial leaning (45°) patterns under different Cd stress. The results indicated considerable tolerance of both upright poplar (UP) and leaning poplar (LP) to Cd stress in the soil, though with significant inhibition from Cd application. LP demonstrated significantly lower height and basal diameter growth than UP. Cd concentrations in different parts of both UP and LP increased with the increase of Cd in the soil and it followed a general order as Bark > Leaf > Root > Stem. Different parts of poplar had average bio-concentration factor (BCF) ranges between 0.08 to 2.36, and average translocation factor (TF) between 0.67 to 7.92, indicating a big difference of phytoextraction ability among the parts, among the treatments, and between LP and UP. Average Cd concentration, BCF, and TF for each part of LP were higher than that of UP, but the difference was not significant. Significantly higher Cd concentration was found in the tension zone of stem wood than that in the opposite zone for LP.

Genome Assembly of Salicaceae Populus deltoides (Eastern Cottonwood) I-69 Based on Nanopore Sequencing and Hi-C Technologies.

Populus deltoides has important ecological and economic values, widely used in poplar breeding programs due to its superior characteristics such as rapid growth and resistance to disease. Although the genome sequence of P. deltoides WV94 is available, the assembly is fragmented. Here, we reported an improved chromosome-level assembly of the P. deltoides cultivar I-69 by combining Nanopore sequencing and chromosome conformation capture (Hi-C) technologies. The assembly was 429.3 Mb in size and contained 657 contigs with a contig N50 length of 2.62 Mb. Hi-C scaffolding of the contigs generated 19 chromosome-level sequences, which covered 97.4% (418 Mb) of the total assembly size. Moreover, repetitive sequences annotation showed that 39.28% of the P. deltoides genome was composed of interspersed elements, including retroelements (23.66%), DNA transposons (6.83%), and unclassified elements (8.79%). We also identified a total of 44 362 protein-coding genes in the current P. deltoides assembly. Compared with the previous genome assembly of P. deltoides WV94, the current assembly had some significantly improved qualities: the contig N50 increased 3.5-fold and the proportion of gaps decreased from 3.2% to 0.08%. This high-quality, well-annotated genome assembly provides a reliable genomic resource for identifying genome variants among individuals, mining candidate genes that control growth and wood quality traits, and facilitating further application of genomics-assisted breeding in populations related to P. deltoides.