Poplar Species Research Articles

Seasonal Changes in Salicylic and Jasmonic Acid Levels in Poplar with Differing Stress Responses

Poplars are essential tree species with critical roles in wood production, ecological conservation, environmental protection, and climate change mitigation. Plants of different poplar populations exhibit varying responses to biotic and abiotic stresses, largely driven by phytohormones—key regulators of plant growth and stress responses. Phytohormones control fundamental processes such as cell division, growth, tissue differentiation, organ development, and resistance to environmental challenges such as temperature extremes and drought. In this study, we conducted a quantitative analysis of phytohormone levels in the leaves of two populations of poplar species from the same geographical region over a one-year period, covering the early, mid, and late growth stages. Our results revealed that salicylic acid (SA) and jasmonic acid (JA) concentrations in the stress-resistant poplar (RP) increased significantly during the late growth stage (September), particularly in response to elevated pathogen pressure and fluctuating climatic conditions. In contrast, the susceptible poplar (SP) consistently exhibited lower levels of SA and JA across all growth stages, particularly during the mid-growth stage (characterized by high temperatures and low precipitation) and the late growth stage, when pathogen stress typically intensifies. The limited increase in phytohormone levels in the SP suggests a weaker defense response compared with the RP. These findings demonstrate that climatic factors significantly influence the phytohormonal dynamics in poplars, with the RP exhibiting more robust regulation of SA and JA to mitigate both biotic and abiotic stresses. This study provides a theoretical framework for better understanding the resistance mechanisms in Populus and offers insights for improving stress tolerance in future breeding programs.

Poplar Adventitious Roots Induced by Stem Canker Pathogens: An Experimental System for Studying Roots Biology and Light Response-Related Processes.

Valsa sordida and Botryosphaeria dothidea are two crucial necrotrophic fungal pathogens that damage many plant hosts, particularly species in the genus Populus. These two fungal pathogens occur mainly in poplar branches, stems, and twigs, causing classic symptoms such as canker lesions, canopy dieback, and wilting. Pathogen inoculation is the most efficient pathway to study the mechanism of plant disease. Besides the canker lesions around the inoculation sites on the stems, a novel developmental phenomenon, copious adventitious roots (ARs) with bright red color, were observed in poplar species after stem canker pathogen inoculations. In this study, we described the method for inducing ARs using fungal pathogens in poplar trees. The crucial step of this method is the pathogen inoculation after (phloem or epidermis) girdling manipulation. The second crucial step is the application of the moisturizing material. Compared to the moisturizing manipulation with Parafilm, wrapping the inoculated sites with household polyethylene (PE) plastic wrap can produce colorful, numerous, and robust ARs in 20 days after girdling-inoculation. Finally, white ARs sprouted from the inoculated rings in the poplar stems after shading treatment (wrapping the stems with aluminum foil). This method introduces a novel experimental system for studying root development and morphogenesis, which is crucial for understanding the biology of root development, morphogenesis, and response under disease stress. Furthermore, when combined with shading treatment, this study can provide a convenient experimental system for investigating light response-related processes, for example, the biosynthesis of flavonoids, anthocyanins, or other related metabolites, and genes or transcription factors involved in these processes.

Estimation of tree height using UAV photogrammetric data

Dimensional characterization of trees plays important roles in phytoremediation project of precision agriculture and environmental protection. The dimensional characterization can be evaluated by using UAV-based geomatic surveys. The work in this study applies low-cost UAV photogrammetry for tree height estimation, particularly for a phytoremediation project on contaminated soils. Two locations that had differing mean tree heights (7m and 4m) were used for the purpose of study. Three different UAV flights were carried out at 40m, 50m, and 60m altitudes in Area 1, an olive grove, and two different flights at 45m and 52m altitudes in Area 2, which has poplar species. The Structure from Motion (SfM) method, Vegetation Filter (VF), Digital Surface Models (DSMs), and Raster computational tool were used to process the UAV point clouds in order to produce Canopy Height Models (CHMs) for a local maximum driven extraction of tree height. Relatively, the results obtained from the tree height estimation experiment for the locations using UAV are higher than the results obtained using in-field measurement, thereby justifying the suitability of UAV photogrammetric data for tree height estimation.

Genome-Wide Identification of the Remorin Gene Family in Poplar and Their Responses to Abiotic Stresses.

The Remorin (REM) gene family is a plant-specific, oligomeric, filamentous family protein located on the cell membrane, which is important for plant growth and stress responses. In this study, a total of 22 PtREMs were identified in the genome of Populus trichocarpa. Subcellular localization analysis showed that they were predictively distributed in the cell membrane and nucleus. Only five PtREMs members contain both Remorin_C- and Remorin_N-conserved domains, and most of them only contain the Remorin_C domain. A total of 20 gene duplication pairs were found, all of which belonged to fragment duplication. Molecular evolutionary analysis showed the PtREMs have undergone purified selection. Lots of cis-acting elements assigned into categories of plant growth and development, stress response, hormone response and light response were detected in the promoters of PtREMs. PtREMs showed distinct gene expression patterns in response to diverse stress conditions where the mRNA levels of PtREM4.1, PtREM4.2 and PtREM6.11 were induced in most cases. A co-expression network centered by PtREMs was constructed to uncover the possible functions of PtREMs in protein modification, microtube-based movement and hormone signaling. The obtained results shed new light on understanding the roles of PtREMs in coping with environmental stresses in poplar species.

Genome-Wide Analysis of Aquaporins Gene Family in Populus euphratica and Its Expression Patterns in Response to Drought, Salt Stress, and Phytohormones.

Aquaporins (AQPs) play an essential role in membrane water transport during plant responses to water stresses centered on conventional upstream signals. Phytohormones (PHs) regulate plant growth and yield, working with transcription factors to help plants withstand environmental challenges and regulate physiological and chemical processes. The AQP gene family is important, so researchers have studied its function and regulatory system in numerous species. Yet, there is a critical gap the understanding of many of their molecular features, thus our full knowledge of AQPs is far-off. In this study, we undertook a broad examination of the AQP family gene in Populus euphratica via bioinformatics tools and analyzed the expression patterns of certain members in response to drought, salt, and hormone stress. A total of 22 AQP genes were examined in P. euphratica, and were categorized into four main groups, including TIPs, PIPs, SIPs, and NIPs based on phylogenetic analysis. Comparable exon-intron gene structures were found by gene structure examination, and similarities in motif number and pattern within the same subgroup was determined by motif analysis. The PeuAQP gene family has numerous duplications, and there is a distinct disparity in how the members of the PeuAQP family react to post-translational modifications. Abiotic stress and hormone responses may be mediated by AQPs, as indicated by the abundance of stress response elements found in 22 AQP genes, as revealed by the promoter's cis-elements prediction. Expression pattern analysis reveals that selected six AQP genes from the PIP subgroup were all expressed in the leaves, stem, and roots with varying expression levels. Moreover, qRT-PCR analysis discovered that the majority of the selected AQP members were up- or down-regulated in response to hormone treatment and abiotic stress. Remarkably, PeuAQP14 and PeuAQP15 appeared to be highly responsive to drought stress and PeuAQP15 exhibited a high response to salt stress. The foliar application of the phytohormones (SA, IAA, GA3, MeJA, and ABA) were found to either activate or inhibit PeuAQP, suggesting that they may mitigate the effects of water shortage of poplar water stress. The present work enhances our knowledge of the practical roles of AQPs in stress reactions and offers fundamental information for the AQP genes in poplar species. It also highlights a direction for producing new varieties of poplar species with drought, salt, and hormone tolerance and holds substantial scientific and ecological importance, offering a potential contribution to the conservation of poplar species in arid regions.

Unravelling the novel sex determination genotype with 'ZY' and a distinctive 2.15-2.95 Mb inversion among poplar species through haplotype-resolved genome assembly and comparative genomics analysis.

Populus tomentosa, an indigenous tree species, is widely distributed and cultivated over 1,000,000 km2 in China, contributing significantly to forest production, ecological conservation and urban-rural greening. Although a reference genome is available for P. tomentosa, the intricate interspecific hybrid origins, chromosome structural variations (SVs) and sex determination mechanisms remain confusion and unclear due to its broad and even overlapping geographical distribution, extensive morphological variations and cross infiltration among white poplar species. We conducted a haplotype-resolved de novo assembly of P. tomentosa elite individual GM107, which comprises subgenomes a and b with a total genome size of 714.9 Mb. We then analysed the formation of hybrid species and the phylogenetic evolution and sex differentiation across the entire genus. Phylogenomic analyses suggested that GM107 likely originated from a hybridisation event between P. alba (♀) and P. davidiana (♂) which diverged at approximately 3.8 Mya. A total of 1551 chromosome SVs were identified between the two subgenomes. More noteworthily, a distinctive inversion structure spanning 2.15-2.95 Mb was unveiled among Populus, Tacamahaca, Turaga, Aigeiros poplar species and Salix, highlighting a unique evolutionary feature. Intriguingly, a novel sex genotype of the ZY type, which represents a crossover between XY and ZW systems, was identified and confirmed through both natural and artificial hybrids populations. These novel insights offer significant theoretical value for the study of the species' evolutionary origins and serve as a valuable resource for ecological genetics and forest biotechnology.

Evaluation of susceptibility poplar species and clones (Populus spp.) against two poplar key pests; Monsteira unicostata and Melanophila picta in Hamadan province

Evaluation of susceptibility poplar species and clones (Populus spp.) against two poplar key pests; Monsteira unicostata and Melanophila picta in Hamadan province

Поверхностная обработка диспергированной водой ковра древесной массы волокнистой плиты (на примере компании «Arian Sina MDF Company»)

This research focuses on the effect of mat water spraying on the production yield and the quality of medium density fiberboard (MDF) on an industrial scale at Arian Sina MDF Company. A total of 180 raw medium density fiberboard panels, each with dimensions of 3.66×1.83×0.016 m, manufactured by the company in 2018, have been used as the experimental samples. These samples have been produced under various conditions, including 3 different groups: 1 – without mat water spraying; 2 and 3 – with mat water spraying using 40 and 50 g/m² of water, correspondingly. Other parameters have included a constant adhesive content (10 % of dry fiber content), a fixed mat moisture content (7 %), and the use of poplar species (70 %) and Eucalyptus camaldulensis (30 %). Additionally, a hardener (at 0.8 % of the dry weight of glue) has been applied. The results have demonstrated that water spraying onto both sides of the mat increases the strength properties and improves the production yield. This enhancement is attributed to the reduced time required for transferring heat from the press plates to the core layer of the mat. Furthermore, X-ray vertical profile density analysis has indicated that water spraying onto the mat surface also increases the surface and core layer density of the panels.

Identification of the Wood Species and Relationship Between the Wood Species Selection and the Occurrence of Biological Diseases in Wooden Components within Ancient Wooden-Structure Building of Songyun Temple

ABSTRACT A comprehensive identification of wooden components in ancient wooden-structure building of Songyun Temple was conducted using optical microscopy based on the basis of wood anatomy. Furthermore, the relationship between wood species selection and biological diseases was discussed. The findings reveal that: (1) Chinese lace-bark pine (Pinus bungeana), hard pines (Pinus subg. Diploxylon), chestnut (Castanea sp.), oak (Quercus sect. Cerris), wing-nut (Pterocarya sp.), Chinese Toon (Toona sinensis), and poplar (Populus spp.) were identified as the predominant wood species utilized for these wooden components. Statistical analysis indicates that hard pines are the primary wood species found in Songyun Temple. (2) Additionally, fungal decay and insect infestation are the predominant types of biological diseases observed in the study. Fungal decay can be detected in all wooden components, with Chinese lace-bark pine, hard pines, Chinese toon, and oak exhibiting particular susceptibility. Carpenter bees inflict more severe damage on chestnut, wing-nut, and Chinese toon species. Oak and poplar species are highly susceptible to powderpost beetle attacks. (3) These biological diseases are intricately linked to the inherent natural durability of various wood species as well as external environmental factors. The findings of this study provide scientific guidance for analyzing the underlying causes of biological diseases in wooden components, implementing protective measures for rescue purposes, and adopting preventive strategies.

Variations in soil microbial communities in different saline soils under typical Populus spp. vegetation in alpine region of the Qaidam Basin, NW China

Salinization is a severe threat to agriculture and the environment in many areas, and the same in Qaidam Basin, Qinghai Province, Northwestern China. Microorganisms have an important influence on regulating the biochemical cycles of ecosystems; however, systematic research exploring microbial diversity and interactions with saline-soil ecosystems’ environmental variables remains scarce. Thus, 16 S rRNA high-throughput sequencing was performed in this paper to characterize microbial diversity under different levels of salinized soils: non-salinized (NS, 2.25 g/L), moderately salinized (MS, 6.14 g/L) and highly salinized (HS, 9.82 g/L). The alpha diversity results showed that the HS soil was significantly different from the NS and MS soils. An analysis of similarity (ANOSIM) and a principal co-ordinates analysis (PCoA) indicated that NS and MS clustered closely while HS separated from the other two. Significant differences in microbial composition were observed at the taxonomic level. Proteobacteria (42.29–79.23 %) were the most abundant phyla in the studied soils. Gammaproteobacteria (52.49 and 66.61 %) had higher abundance in the MS and HS soils at the class level; Methylophaga and Pseudomonas were the predominant bacteria in the HS soil; and Azotobacter and Methylobacillus were abundant in the MS soil. Most genera belonging to Proteobacteria and Actinobacteria were detected via a linear discriminate analysis (LDA) effect size (LEfSe) analysis, which indicated that microbes with the ability to degrade organic matter and accomplish nutrient cycling can be well-adapted to salt conditions. Further analyses (redundancy analysis and Mantel test) showed that the microbial communities were mainly related to the soil salinity, electrical conductivity (EC1:5), total phosphorus (TP) and ammonia nitrogen (NH4+-N). Overall, the findings of the study can provide insights for better understanding the dominant indigenous microbes and their roles in biochemical cycles in different saline soils in the Qaidam Basin, Qinghai Province, China. The researches related to microbial community under typical poplar species should further clarify the mechanism of plant-microbial interaction and benefit for microbial utilization in salt soil remediation.

Transgenic poplar (Populus davidiana×P. bolleana Loucne) expressing dsRNA of insect chitinase gene: lines identification and resistance assay.

Poplar is a valuable tree species that is distributed all over the world. However, many insect pests infest poplar trees and have caused significant damage. To control poplar pests, we transformed a poplar species, Populus davidiana × P. bolleana Loucne, with the dsRNA of the chitinase gene of a poplar defoliator, Clostera anastomosis (Linnaeus) (Lepidoptera: Notodontidae), employing an Agrobaterium-mediated approach. The transgenic plant has been identified by cloning the T-DNA flanking sequences using TAIL-PCR and quantifying the expression of the dsRNA using qPCR. The toxicity assay of the transgenic poplar lines was carried out by feeding the target insect species (C. anastomosis). The results showed that, in C. anastomosis, the activity of chitinase was significantly decreased, consistent with the expression on mRNA levels, and the larval mortality was significantly increased. These results suggested that the transgenic poplar of dsRNA could be used for pest control.

Genome-wide identification of bHLH gene family and its response to cadmium stress in Populus × canescens.

The basic helix-loop-helix (bHLH) gene family is integral to various aspects of plant development and the orchestration of stress response. This study focuses on the bHLH genes within Populus × canescens, a poplar species noted for its significant tolerance to cadmium (Cd) stress. Through our comprehensive genomic analysis, we have identified and characterized 170 bHLH genes within the P. canescens genome. These genes have been systematically classified into 22 distant subfamilies based on their evolutionary relationships. A notable conservation in gene structure and motif compositions were conserved across these subfamilies. Further analysis of the promoter regions of these genes revealed an abundance of essential cis-acting element, which are associated with plant hormonal regulation, development processes, and stress response pathway. Utilizing quantitative PCR (qPCR), we have documented the differential regulation of PcbHLHs in response to elevated Cd concentrations, with distinct expression patterns observed across various tissues. This study is poised to unravel the molecular mechanism underpinning Cd tolerance in P. canescens, offering valuable insights for the development of new cultivars with enhanced Cd accumulation capacity and tolerance. Such advancements are crucial for implementing effective phytoremediation strategies to mitigate soil pollution caused by Cd.

Possible Factors of Poplar Susceptibility to Large Poplar Borer Infestation

Poplars (Populus spp.) are of significant ecological and economic importance. Long-term breeding efforts were aimed mainly at obtaining fast-growing and productive plants and less considered resistance to pests. This study aimed to identify patterns of susceptibility or resistance to Saperda carcharias (Linnaeus, 1758) (Coleoptera: Cerambycidae) infestation among clones of Populus hybrids and pure species, focusing on the influence of their placement, seasonal development, stem diameter, height increment, and crossing combinations. Among 34 clones of poplar species and hybrids of Ukrainian and foreign selection, in 2019–2023 S. carcharias infested 14 clones every year. Six clones (‘Ivantiivska’, ‘Kytaiska × pyramidalna’, ‘Volosystoplidna’, ‘Novoberlinska-3’, ‘Robusta’, and ‘Lada’) were the most susceptible to the infestation by S. carcharias. The clones of all presented poplar sections and their crossing combinations, except the Tacamahaca and Leucoides cross, were infested. Greater height increment promoted the infestation by S. carcharias. Ambiguous results were obtained regarding the susceptibility of Populus hybrids compared to pure species to S. carcharias infestations. Considering infestation by S. carcharias and plant placement in the site, it can be concluded that the clones ‘Sakrau45-51’, ‘Deltopodibna’, ‘Rosijska’, ‘Slava Ukrayiny’, ‘Lubenska’, ‘Rohanska’, and ‘Nocturne’ are resistant to this pest. Selecting native species clones or creating mixed clone plantations could enhance the resilience of poplar plantations to pest threats.

Genome-wide analysis of the poplar homeobox gene family and the identification of PtHB180 as an important regulator of plant developmental processes and drought stress response

Homeobox (HB) transcription factors have been reported to regulate various developmental processes and hormone signaling and mediate plant adaption to abiotic stresses, including drought. As a major subfamily of HB family, KNOX genes have been widely studied in herbaceous plants. However, the behaviors of KNOX genes in regulating plant developmental processes and stress resistance in woody plants remain poorly understood. Here, we found a KNOX family gene in the model tree species Populus trichocarpa (hereafter “poplar”), PtHB180, which enhances drought tolerance by regulating developmental processes through auxin and gibberellin pathways and mediating the ABA signaling pathway leading to rapid stomatal closure. Overexpression lines of PtHB180 (PtHB180-OE) displayed pleiotropic phenotypes, including increased plant height and decreased leaf area by affecting auxin and/or gibberellin contents and signaling. PtHB180-OE plants also displayed improved drought tolerance under short- and long-term drought stress. Results of transcriptome sequencing suggested the involvement of genes related to ABA signaling in regulating drought tolerance in PtHB180-OE. Specifically, PtHB180-OE plants showed significantly enhanced stomatal sensitivity to exogenous ABA. Taken together, our results indicate that PtHB180 enhances drought tolerance in poplar via regulating plant architecture and mediating ABA signaling to close stomata. Therefore, PtHB180 can be used as a potential candidate gene to improve drought tolerance by genetic transformation in poplar and related plant species.

Application High-Performance Thin-Layer Chromatography with Controlled Eluent Velocity to Determine Fingerprints of Various Poplar Species Buds Extracts: Optimization of Operating Variables

The study used the prototype device enabling the development of isocratic and gradient thin-layer chromatograms with controlled eluent velocity to obtain fingerprints of extracts from buds of various poplar species. This equipment can deliver an eluent to virtually any place on the adsorbent layer of the chromatographic plate. Moreover, the composition of a mobile phase can be easily modified even when the chromatogram is developing. This paper shows the effect of various operating variables of the prototype in a normal phase system, e.g., eluent velocity and composition, on the chromatographic behavior of the mixture. The prototype’s results were compared to conventional TLC development in horizontal DS chambers. The UV light (366 nm) was used to detect the solute zones and document both systems. The results prove that the prototype device has great potential in plant material standardization. The mobile phase gradient improves the separation of the bands of strongly retained solutes. Additionally, this fact does not enhance the blurring of low-retained bands.

Differences in mineral and osmotic balances enhance zinc translocation in an aquaporin overexpressing poplar

Zinc (Zn) is an essential micronutrient for plants, but it is toxic beyond a certain threshold. Populus alba (L.) ‘Villafranca’ clone is known for its good tolerance to high Zn concentration compared to other poplar species. A line of this species overexpressing the tonoplast intrinsic aquaporin AQUA1 gene has showed an improved tolerance to Zn excess in comparison to the wild-type (wt) line. The aims of this work were to: 1) verify if AQUA1 plants can uptake Zn more efficiently after a longer period of exposure; 2) evaluate if a higher Zn uptake in transgenic lines can have negative effects; 3) assess Zn competing elements (iron and manganese), soluble sugars, osmolytes, and potassium to investigate differences in water and osmotic homeostasis between lines. Under Zn excess, AQUA1 plants showed a twofold Zn translocation factor and a higher xylem sap Zn concentration than the wt plants. Transgenic plants preferentially allocated Zn in aerial biomass and this different behaviour matched with modified manganese and iron balances suggesting that the increased Zn uptake might be related to a decrease in iron transport in the transgenic line. Moreover, a higher instantaneous water use efficiency in control conditions and an increase in bark soluble sugars under Zn excess could allow a higher resistance of AQUA1 plants to the water and osmotic perturbations caused by Zn. Indeed, the Zn excess increased the xylem osmolyte content only in wt plants. Further investigations are required to understand the role of AQUA1 in osmotic regulation.

Design, implementation, and evaluation of a short rotation coppice system for wastewater treatment and resource recovery in India

Despite growing health concerns and increasing water scarcity, adequate wastewater treatment and reuse remains limited in India. Low-cost, decentralised, and nature-based on-site sanitation systems could play a key role in a circular water approach. This paper evaluates the performance of a Wastewater Fertigated Short Rotation Coppice (wfSRC) system based on willow, poplar, and bamboo species as a potential solution, offering low-cost, efficient water treatment, and high biomass production. Through a full-scale wfSRC pilot plant (250 m3·day−1 municipal wastewater on 6864 m2) established at Aligarh Muslim University, Uttar Pradesh, India, treatment capacities, biomass production rates, and contamination tolerance of different willow, poplar, and bamboo species were investigated. The chemical compositions of incoming wastewater, percolation water, soil, and biomass were monitored regularly. Despite the high load, all plant sections of the wfSRC system showed efficient removal of wastewater-originated pollutants. BOD5 and COD removal efficiencies were up to 99% and 95% respectively. Removal efficiencies for PO4-P reached 93% and for TN 91%. In general, total nitrogen and phosphate loads appear to be the limiting design parameters under the conditions at Aligarh to meet all discharge limits in India. Biomass production was projected to be >225 tDM·ha−1·yr−1 for bamboo, 65 tDM·ha−1·yr−1 for willow, and 206 tDM·ha−1·yr−1 for poplar. The pilot, conducted from March 2022 to June 2023, showcased how these densely planted agroforestry systems can effectively treat wastewater through natural processes such as oxidation, microbial degradation, and plant uptake. The findings demonstrate wfSRC's potential to serve as a nature-based, sustainable approach to wastewater treatment, particularly beneficial for suburban and rural areas in India and similar regions worldwide. This paper also provides recommendations for future implementation of wfSRC systems, emphasizing the need for careful planning regarding plant selection, system design, and operational strategies to maximize treatment efficiency and biomass production.

Simplified Method for Agrobacterium-Mediated Genetic Transformation of Populus x berolinensis K. Koch.

The rapid advancement of genetic technologies has made it possible to modify various plants through both genetic transformation and gene editing techniques. Poplar, with its rapid in vitro growth and regeneration enabling high rates of micropropagation, has emerged as a model system for the genetic transformation of woody plants. In this study, Populus × berolinensis K. Koch. (Berlin poplar) was chosen as the model organism due to its narrow leaves and spindle-shaped crown, which make it highly suitable for in vitro manipulations. Various protocols for the Agrobacterium-mediated transformation of poplar species have been developed to date. However, the genetic transformation procedures are often constrained by the complexity of the nutrient media used for plant regeneration and growth, which could potentially be simplified. Our study presents a cheaper, simplified, and relatively fast protocol for the Agrobacterium-mediated transformation of Berlin poplar. The protocol involved using internode sections without axillary buds as explants, which were co-cultivated in 10 µL droplets of bacterial suspension directly on the surface of a solid agar-based medium without rinsing and sterile paper drying after inoculation. We used only one regeneration Murashige and Skoogbased medium supplemented with BA (0.2 mg·L-1), TDZ (0.02 mg·L-1), and NAA (0.01 mg·L-1). Acetosyringone was not used as an induction agent for vir genes during the genetic transformation. Applying our protocol and using the binary plasmid pBI121 carrying the nptII selective and uidA reporter genes, we obtained the six transgenic lines of poplar. Transgenesis was confirmed through a PCR-based screening of kanamycin-selected regenerants for the presence of both mentioned genes, Sanger sequencing, and tests for detecting the maintained activity of both genes. The transformation efficiency, considering the 100 explants taken originally, was 6%.

Assessment of biomass and carbon storage of a Populus simonii windbreak located in the Western Cape Province, South Africa

The integration of trees within agricultural systems delivers the opportunity to provide multiple benefits over those afforded by agriculture without trees. The use of windbreaks as a form of agroforestry, in water scarce environments, is primarily used to reduce windspeeds in order to decrease evapotranspiration. Quick growing poplar species such as Populus simonii ((Carrière) Wesm.) are frequently utilised within windbreak structures, but to date, few allometric equations are available to quantify biomass production and to make inferences about carbon storage potential of this species, and none outside the forest. To fill this knowledge gap, we destructively sampled 17 P. simonii growing within a windbreak on a wine estate in the Western Cape Provence, South Africa. Power functions were constructed to explain tree height, whole tree aboveground woody biomass, stem and branch biomass as a function of stem diameter at 1.3 m. Additional functions were developed to predict individual branch length and biomass based on branch stub diameter. The presented models explained each variable with high significance. The models could be used to estimate carbon stock per km of windbreak for the given example. Furthermore, bark percentage predicted by stem sectional diameter was modelled to provide a function that can separate wood and bark fractions as a further outlook for the species’ utilisation.

Interspecific variations in growth, physiology and Cd accumulation between Populus deltoides and P. × canadensis in response to Cd pollution under two soil types

Both acid and alkaline purple soils in China are increasingly affected by Cd contamination. The selection of fast-growing trees suitable for remediating different soil types is urgent, yet there is a severe lack of relevant knowledge. In this study, we conducted a controlled pot experiment to compare the growth, physiology, and Cd accumulation efficiency of two widely recognized poplar species, namely Populus deltoides and P. × canadensis, under Cd contamination (1 mg kg−1) in acid and alkaline purple soils. The objective was to determine which poplar species is best suited for remediating different soil types. Our findings are as follows: (1) the total biomass of both poplars remained largely unaffected by Cd pollution in both soil types. Notably, under Cd pollution, the total biomass of P. deltoides in acid purple soil was 1.53 times greater than that in alkaline purple soil. (2) Cd pollution did not significantly induce oxidative damage in the leaves of either poplar species in both soil types. However, in acid purple soil, Cd contamination led to a 21% increase in NO3- concentration and a 44% increase in NH4+ concentration in P. × canadensis leaves, whereas in alkaline purple soil, it led to a 59% increase in NH4+ concentration in P. deltoides leaves. (3) Cd concentrations in all root orders of P. × canadensis were significantly higher than those in P. deltoides, especially in the first three root orders, under alkaline purple soil. The total Cd accumulation by P. × canadensis in Cd-polluted alkaline purple soil was 2.18 times higher than that in Cd-polluted acid purple soil, a difference not observed in P. deltoides. (4) redundancy analysis indicated that the sequestration effect of higher soil organic matter on Cd availability in acid purple soil was more pronounced than the release effects caused by lower pH. In conclusion, P. × canadensis is better suited for remediating alkaline purple soil due to its higher capacity for Cd uptake, while P. deltoides is more suitable for remediating Cd-contaminated acid purple soil due to its better growth conditions and greater Cd enrichment capability.