Hybrid Populus Research Articles

Induced and natural variation affect traits independently in hybrid Populus.

The genetic control of many plant traits can be highly complex. Both allelic variation (sequence change) and dosage variation (copy number change) contribute to a plant's phenotype. While numerous studies have investigated the effect of allelic or dosage variation, very few have documented both within the same system, leaving their relative contribution to phenotypic effects unclear. The Populus genome is highly polymorphic, and poplars are fairly tolerant of gene dosage variation. Here, using a previously established Populus hybrid F1 population, we assessed and compared the effect of natural allelic variation and induced dosage variation on biomass, phenology and leaf morphology traits. We identified QTLs for many of these traits, but our results indicate limited overlap between the QTLs associated with natural allelic variation and induced dosage variation. Additionally, the integration of data from both allelic and dosage variation identifies a larger set of QTLs that together explain a larger percentage of the phenotypic variance. Finally, our results suggest that the effect of the large indels might mask that of allelic QTLs. Our study helps clarify the relationship between allelic and dosage variation and their effects on quantitative traits.

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.

Characterization of Secondary Metabolites of Leaf Buds from Some Species and Hybrids of Populus by Gas Chromatography Coupled with Mass Detection and Two-Dimensional High-Performance Thin-Layer Chromatography Methods with Assessment of Their Antioxidant Activity.

Poplars provide medicinal raw plant materials used in pharmacy. Leaf buds are one of the herbal medicinal products collected from poplars, having anti-inflammatory and antiseptic properties, but there are no quality standards for their production and there is a need to determine their botanical sources. Therefore, the chemical compositions of the leaf buds from four species and varieties of poplars, Populus balsamifera, P. × berolinensis, P. × canadensis 'Marilandica', and P. wilsonii were investigated and compared using gas chromatography coupled with mass detection (GC-MS) and two-dimensional high-performance thin-layer chromatography (2D-HPTLC) in order to search for taxa characterized by a high content of biologically active compounds and with a diverse chemical composition that determines their therapeutic effects. The presence of 163 compounds belonging to the groups of flavonoids, phenolic acids derivatives, glycerides, and sesquiterpenes was revealed. Moreover, the conditions for the separation and identification of biologically active compounds occurring in analyzed leaf buds using 2D-HPTLC were optimized and used for metabolomic profiling of the studied poplars, enabling their fast and simple botanical identification. The total phenolic (TPC) and flavonoid (TFC) contents of examined extracts were determined and their antioxidant capacities were estimated by spectrophotometric DPPH, ABTS, and FRAP assays. Based on the analysis of phytochemicals and antioxidant activity, P. × berolinensis buds were selected as the raw plant material for medicinal purposes with the highest content of active compounds and the strongest antioxidant activity.

Populus euphratica GRP2 Interacts with Target mRNAs to Negatively Regulate Salt Tolerance by Interfering with Photosynthesis, Na+, and ROS Homeostasis.

The transcription of glycine-rich RNA-binding protein 2 (PeGRP2) transiently increased in the roots and shoots of Populus euphratica (a salt-resistant poplar) upon initial salt exposure and tended to decrease after long-term NaCl stress (100 mM, 12 days). PeGRP2 overexpression in the hybrid Populus tremula × P. alba '717-1B4' (P. × canescens) increased its salt sensitivity, which was reflected in the plant's growth and photosynthesis. PeGRP2 contains a conserved RNA recognition motif domain at the N-terminus, and RNA affinity purification (RAP) sequencing was developed to enrich the target mRNAs that physically interacted with PeGRP2 in P. × canescens. RAP sequencing combined with RT-qPCR revealed that NaCl decreased the transcripts of PeGRP2-interacting mRNAs encoding photosynthetic proteins, antioxidative enzymes, ATPases, and Na+/H+ antiporters in this transgenic poplar. Specifically, PeGRP2 negatively affected the stability of the target mRNAs encoding the photosynthetic proteins PETC and RBCMT; antioxidant enzymes SOD[Mn], CDSP32, and CYB1-2; ATPases AHA11, ACA8, and ACA9; and the Na+/H+ antiporter NHA1. This resulted in (i) a greater reduction in Fv/Fm, YII, ETR, and Pn; (ii) less pronounced activation of antioxidative enzymes; and (iii) a reduced ability to maintain Na+ homeostasis in the transgenic poplars during long-term salt stress, leading to their lowered ability to tolerate salinity stress.

Amphidiploid production of a distant hybrid Populus simonii × P. euphratica cv. ‘Xiaohuyang-1’ and resulting in phenotypic variation

Amphidiploid production of a distant hybrid Populus simonii × P. euphratica cv. ‘Xiaohuyang-1’ and resulting in phenotypic variation

Suitability of Salicaceae genotypes to produce biomass using industrial wastewater

Water circularity is a challenge which must be met to guarantee the sustainability of this resource. Woody biomass is another resource of interest for the bioeconomy, which has multiple uses and acts as a carbon sink. Combining both aspects involves establishing wastewater irrigated plantations, the so-called Vegetation Filters. The aim in this research was to contribute towards assessing the suitability of different Salicaceae genotypes for enhancing the efficiency of these simultaneous processes. Twenty-three genotypes of different species and hybrids of the genera Populus and Salix were irrigated using brewery wastewater under controlled conditions (in a greenhouse using hydroponic cultivation or in pots with substrate) and in the field. Although the application of wastewater reduced the overall production, relevant differences among the genotypes were detected. Growth, physiological activity and nitrogen and electric conductivity (EC) attenuation efficiency provided good criteria for selection, although given the interaction with site conditions it is essential that plant material is selected based on its adaptation to the environment. The poplar hybrids ‘2000 Verde’ and ‘I-214’ showed the highest rates of net photosynthesis and transpiration, with high percentages of N removal and moderate biomass production, these two initially being considered of interest for the purposes outlined above. The ‘AF34’ genotype showed the highest production in the field, followed by the ‘Levante’ willow hybrid. The white poplar ‘PO-10-10-20’, which presented moderate production in the field, is also of interest due to its autochthony, which can be advantageous in certain environments.

Microsporogenesis in the triploid hybrid ‘Beilinxiongzhu 1#’ and detection of primary trisomy in 2x × 3 × Populus hybrids

BackgroundPrimary trisomy is a powerful genetic tool in plants. However, trisomy has not been detected in Populus as a model system for tree and woody perennial plant biology.ResultsIn the present study, a backcross between Populus alba × Populus glandulosa ‘YXY 7#’ (2n = 2x = 38) and the triploid hybrid ‘Beilinxiongzhu 1#’ (2n = 3x = 57) based on the observation of microsporogenesis and an evaluation of the variations in pollen was conducted to create primary trisomy. Many abnormalities, such as premature migration of chromosomes, lagging of chromosomes, chromosome bridges, asymmetric separation, micronuclei, and premature cytokinesis, have been detected during meiosis of the triploid hybrid clone ‘Beilinxiongzhu 1#’. However, these abnormal behaviors did not result in completely aborted pollen. The pollen diameter of the triploid hybrid clone ‘Beilinxiongzhu 1#’ is bimodally distributed, which was similar to the chromosomal number of the backcross progeny. A total of 393 progeny were generated. We provide a protocol for determining the number of chromosomes in aneuploid progeny, and 19 distinct simple sequence repeat (SSR) primer pairs covering the entire Populus genome were developed. Primary trisomy 11 and trisomy 17 were detected in the 2x × 3 x hybrid using the SSR molecular markers and counting of somatic chromosomes.ConclusionsNineteen distinct SSR primer pairs for determining chromosomal number in aneuploid individuals were developed, and two Populus trisomies were detected from 2x × 3 x hybrids by SSR markers and somatic chromosome counting. Our findings provide a powerful genetic tool to reveal the function of genes in Populus.

Effects of sexual polyploidization on reproductive development in a full-sib poplar family

Populus is an important source of woody biomass in the Northern Hemisphere. Sexual polyploidization plays a valuable role in the genetic improvement of Populus, resulting in tremendous variation in phenotypic traits. Most studies have focused on the variations in the vegetative growth of allopolyploid Populus; however, variations in the reproductive development of different polyploid genotypes of the progeny remain unclear. In this study, catkin traits, pollen size and viability, meiotic development, and reproductive ability were analyzed based on a full-sib family including diploid and triploid hybrids of (Populus pseudo-simonii × P. nigra ‘Zheyin3#’) × (P. × beijingensis) to understand the effects of sexual polyploidization on reproductive development in Populus hybrids. Catkin traits varied among the genotypes in the full-sib family. A ploidy change resulted in significant variation in male catkin length and male flower number per catkin but not in female catkin traits, suggesting that Populus catkin development may be more sensitive to respond to a change in ploidy level in male plants than in female plants. The male diploid hybrids had significantly smaller pollen grains, but higher pollen germination rates than the triploid hybrids. Giant pollen grains with large diameters were recorded in all-male diploid and triploid hybrids, which were speculated to be unreduced gametes. Premature cytokinesis, misorientation of the spindles, and aberrant cytokinesis were observed in a cytological analysis, which explained the production of unreduced pollen. Premature cytokinesis was only detected in triploid hybrids, which might be attributed to a ploidy change. The frequencies of meiotic abnormalities, such as precocious chromosomal migration, chromosome bridges, and micronuclei in the triploid hybrids were higher than those in diploid hybrids, suggesting that the unbalanced chromosomes in the triploid hybrids caused more complex meiotic chromosome behaviors. Backcrosses with the triploid hybrids resulted in low seed sets and seed germination rates, suggesting that polyploidization reduced pollen viability. Our findings provide new insight into the effect of sexual polyploidization on reproductive development in Populus and could be used to guide a Populus polyploid breeding program.

Detection of genetic identity for hybrid Populus x canadensis trees along the Seyhan River

Populus x canadensis hybrids play an important role for the commercial poplar cultivation with good growth performance and adaptability in the world. Hybrid clones introduced the different region of Turkey replaced the native stands of Populus nigra gradually. Along the Seyhan River there are many mature and young hybrid poplar trees despite of less number of P. nigra as a result of hybrid plantations growing near the river. To detect the genetic identity of hybrid trees, 17 microsatellite markers were studied. Out of ten hybrid trees, seven trees had the different genotype. From the results of current study it is seen that hybrid poplar species reproduce at larger distances from the plantation sites and colonize riparian habitat thereby competing for resources with the native P. nigra species and threaten the genetic diversity of the species with genetic pollution via intogression. From the field trip observation and obtained genetic results, conservation of the native P. nigra trees is an important requirements to prevent the reduction of effective population size and population density. Establishing more seed sources of black poplar over the river stretch could provide the establishment of mainly pure black poplar seedlings nearby the parental stands.

Performance and Genetic Parameters of Poplar Hybrids and Clones in a Field Trial Are Modified by Contrasting Environmental Conditions during the Vegetative Propagation Phase.

This study investigates epigenetics-like phenomena: how performance phenotypic plasticity, genotypic variation, and the heritability of growth traits and total phenolic compounds of Populus hybrids and clones in field trials may be modified by contrasting temperature conditions at their vegetation propagation phase. The significant effect of rooting–growing conditions on further tree performance in field trials was found for height increment in 2020, although the interaction hybrid by rooting–growing conditions was highly significant for phenolic compounds, tree height, and diameter, meaning that the performance of some hybrids was affected by rooting–growing conditions, thus demonstrating epigenetic-like effects. For phenolic compounds, interactions were also significant at the clonal level. High estimates of ecovalency indicate that some hybrids are ecologically sensitive, and epigenetic-like phenomena might occur. Hybrid P. balsamifera × P. trichocarpa is characterized by high ecovalency and specific adaptations according to mean tree height when vegetatively propagated under different rooting–growing conditions. Low estimates of P. deltoides × P. trichocarpa ecovalency demonstrate a general adaptation according to mean tree height in a field trial. Vegetative propagation conditions have also altered the genetic variation of traits in trees being planted in field trials.

Field assessment of trace element phytoextraction by different Populus clones established on brownfields in southern Quebec (Canada)

Fast-growing hybrid poplars have been tested for their potential to remove trace elements (TE) from polluted soil in several temperate regions. Despite their potential, they have rarely been tested in countries with a cold temperate climate. The current study screened four different Populus hybrids for phytoextraction of four TEs (i.e., As, Cu, Pb, and Zn) on an abandoned brownfield site in southern Quebec (Canada). The main results showed that under the current experimental conditions, the most important traits determining the actual phytoextraction rate are Biological Concentration Factor (BCF) and TE accumulation in the aboveground biomass, rather than biomass productivity. Although the overall performance of the chosen hybrids was rather poor, the presence of poplar stands enhanced the movement of mobile contaminants in soil, which led to an increase in their concentration in the root zone. This aspect suggests possible strategies for using these plants with high transpiration rates in future phytoremediation projects, including either possible rotation with more effective TE phytoextractor plants (e.g., hyperaccumulators) that can remove high TE amounts that have migrated from the deeper soil layers following poplar plantation, or phytostabilization.

Evaluation of Synergy Between Lignite and Carbonized Biomass During Co-Combustion

Abstract Synergy often occurs between coal and biomass during co-utilization, and the combustion reactivity and combustion properties of coal are affected mainly due to high volatile matter in biomass. However, it is not clear that a synergistic interaction will be encountered if coal is processed with biochar that contains a limited amount of volatiles due to charring process. In this article, the existence of synergy was questioned based on the thermal analysis data obtained from the co-combustion of several biochars and lignite. The biochars produced at 400 °C from lignocellulosic biomasses such as Fraxinus (FR—ash tree), Populus hybrids (PO—hybrid poplar), and Rhododendron (RH) were blended with Turkish lignite (Adıyaman-Golbasi) to form blends that contain 5–15% biochars. These blends were burned in a thermogravimetric analyzer, and the combustion characteristics of the blends were evaluated, considering the criteria that include the reactivity and combustion performance indices including ignition index, comprehensive combustion index, burnout performance index, combustion stability indices, and rate and intensity index. Also, synergy indices such as synergy indicator, synergy factor, and interaction coefficient were calculated to identify the presence and intensity of synergy. It was concluded that depending on the type of biochar and the addition rate, changes occurred in the combustion properties of the coal, which can sometimes be considered as additive behavior and sometimes as a synergistic interaction. The presence of 5% or 10% PO biochar in the blends resulted in very obvious synergies in combustion characteristics according to all eight criteria considered.

Differences in Environmental and Hormonal Regulation of Growth Responses in Two Highly Productive Hybrid Populus Genotypes

Phenotypic plasticity, in response to adverse conditions, determines plant productivity and survival. The aim of this study was to test if two highly productive Populus genotypes, characterised by different in vitro etiolation patterns, differ also in their responses to hormones gibberellin (GA) and abscisic acid (ABA), and to a GA biosynthesis inhibitor paclobutrazol (PBZ). The experiments on shoot cultures of ‘Hybrida 275′ (abbr. H275; Populus maximowiczii × P. trichocarpa) and IBL 91/78 (Populus tremula × P. alba) were conducted by either modulating the physical in vitro environment or by adding specific chemicals to the nutrient medium. Our results revealed two main sets of differences between the studied genotypes in environmental and hormonal regulation of growth responses. First, the genotype H275 responded to darkness with PBZ-inhibitable shoot elongation; in contrast, the elongation of IBL 91/78 shoots was not affected either by darkness or PBZ treatment. Secondly, the explants of H275 were unable to recover their growth if it was inhibited with ABA; in contrast, those of IBL 91/78 recovered so well after the temporal inhibition by ABA that, when rooted subsequently, they developed longer shoots and roots than without a previous ABA treatment. Our results indicate that GA catabolism and repressive signalling provide an important pathway to control growth and physiological adaptation in response to immediate or impending adverse conditions. These observations can help breeders define robust criteria for identifying genotypes with high resistance and productivity and highlight where genotypes exhibit susceptibility to stress.

In vitro amphidiploid induction of a distant hybrid Populus simonii × P. euphratica cv. ‘Xiaohuyang-2’ and its effect on plant morphology and anatomy

Abstract Highly gametic sterility of a distant hybrid Populus simonii × P. euphratica cv. ‘Xiaohuyang-2’ restricts its utilization in breeding programs of Populus. Amphidiploid induction by somatic chromosome doubling is expected to restore its gametic fertility. In this study, nodal-segment and leaf explants of ‘Xiaohuyang-2’ were used to induce chromosome doubling with colchicine in vitro. Although chromosome doubling of the nodal-segment explants only produced mixoploids, the treatments of leaf explants on adventitious bud regeneration medium successfully produced 4 amphidiploids, which might be attributed to the direct organogenesis of the adventitious buds on the leaf explants. This is the first report of amphidiploid induction in a distant hybrid between Populus section Tacamahaca and sect. Turanga. The highest amphidiploid induction frequency was 16.7 %. Both the explant survival rate and polyploidization frequency were significantly affected by colchicine concentration and exposure time. The amphidiploid plants significantly differed from the diploid and mixoploid plants in morphological and anatomical characteristics. They had larger, thicker, and greener leaves than the diploids and mixoploids. The increase in ploidy level also resulted in changes in stomatal features. The induced amphidiploid plants of the distant hybrid ‘Xiaohuyang-2’ are expected to play important roles in breeding programs of Populus in the future, which can be used as a bridge parent with the ability of unreduced gamete formation to cross with fast-growth germplasms to produce triploids pyramiding desirable traits of fast growth, easy cutting propagation, and salt and drought tolerances.

Analysis of the Genotype Interaction of Four-Year-Old Populus euramericana Using the BLUP-GGE Technique

Poplar is a commercially globalized tree species that provides energy and economic and ecological support. To evaluate the twelve hybrid Populus euramericana genotypes developed in China, a total of six locations were selected for the current study, comprising four climatic types and three kinds of soil. The objective of this study was to characterize the early stages of Populus euramericana growth and to test the locations; to identify good genotypes for stable and high yield; and to offer practical experience and technical assistance for further breeding of Populus euramericana. The main research methods included the statistical description of tree heights and diameter at breast height (DBH), the establishment of a mixed effect model to analyze the genotype and environmental interaction effect (G × E), the use of best linear unbiased prediction (BLUP) values as GGE biplots to achieve visual screening, and the calculation of genetic parameters. Results show that the genotype effect (G), the environmental effect (E), and the G × E interaction is significant; the BLUP value has a strong correspondence with the observed value; the goodness of fit of all biplots can explain more than 85% of the variation; the broad-sense heritability of tree height and DBH is 0.13 and 0.3, respectively; and the type-B correlation is 0.36 and 0.65. In addition, G5, G7, G4, and G9 are excellent genotypes with high yield and stability; using the tree height and DBH of these four genotypes can achieve genetic gains of 3.35% and 0.81%. The conclusions of this study are as follows: the rank-change and scale-effect interactions were distinct; G, E, and G × E all had a significant effect on the growth of poplar trees during their early stage; G4, G5, G7, and G9 genotypes have favorable development characteristics; and N146 is an excellent source of paternal genetics.

Molecular Karyotyping on Populus simonii × P. nigra and the Derived Doubled Haploid.

The molecular karyotype could represent the basic genetic make-up in a cell nucleus of an organism or species. A doubled haploid (DH) is a genotype formed from the chromosome doubling of haploid cells. In the present study, molecular karyotype analysis of the poplar hybrid Populus simonii × P. nigra (P. xiaohei) and the derived doubled haploids was carried out with labeled telomeres, rDNA, and two newly repetitive sequences as probes by fluorescence in situ hybridization (FISH). The tandem repeats, pPC349_XHY and pPD284_XHY, with high-sequence homology were used, and the results showed that they presented the colocalized distribution signal in chromosomes. For P. xiaohei, pPD284_XHY produced hybridizations in chromosomes 1, 5, 8, and 9 in the hybrid. The combination of pPD284_XHY, 45S rDNA, and 5S rDNA distinctly distinguished six pairs of chromosomes, and the three pairs of chromosomes showed a significant difference in the hybridization between homologous chromosomes. The repeat probes used produced similar FISH hybridizations in the DH; nevertheless, pPD284_XHY generated an additional hybridization site in the telomere region of chromosome 14. Moreover, two pairs of chromosomes showed differential hybridization distributions between homologous chromosomes. Comparisons of the distinguished chromosomes between hybrid and DH poplar showed that three pairs of chromosomes in the DH presented hybridization patterns that varied from those of the hybrid. The No. 8 chromosome in DH and one of the homologous chromosomes in P. xiaohei shared highly similar FISH patterns, which suggested the possibility of intact or mostly partial transfer of the chromosome between the hybrid and DH. Our study will contribute to understanding the genetic mechanism of chromosomal variation in P. xiaohei and derived DH plants.

The Impact of Different Environmental Conditions during Vegetative Propagation on Growth, Survival, and Biochemical Characteristics in Populus Hybrids in Clonal Field Trial

To have a cleaner environment, good well-being, and improve the health of citizens it is necessary to expand green urban and suburban areas using productive and adapted material of tree species. The quality of urban greenery, resistance to negative climate change factors and pollution, as well as efficiency of short-rotation forestry in suburban areas, depends primarily on the selection of hybrids and clones, suitable for the local environmental conditions. We postulate that ecogenetic response, phenotypic plasticity, and genotypic variation of hybrid poplars (Populus L.) grown in plantations are affected not only by the peculiarities of hybrids and clones, but also by environmental conditions of their vegetative propagation. The aim of the present study was to estimate growth and biochemical responses, the phenotypic plasticity, genotypic variation of adaptive traits, and genetically regulated adaptability of Populus hybrids in field trials which may be predisposed by the simulated contrasting temperature conditions at their vegetative propagation phase. The research was performed with the 20 cultivars and experimental clones of one intraspecific cross and four different interspecific hybrids of poplars propagated under six contrasting temperature regimes in phytotron. The results suggest that certain environmental conditions during vegetative propagation not only have a short-term effect on tree viability and growth, but also can help to adapt to climate change conditions and grow successfully in the long-term. It was found that tree growth and biochemical traits (the chlorophyll A and B, pigments content and the chlorophyll A/B ratio) of hybrid poplar clones grown in field trials, as well as their traits’ genetic parameters, were affected by the rooting-growing conditions during vegetative propagation phase. Hybrids P. balsamifera × P. trichocarpa, and P. trichocarpa × P. trichocarpa have shown the most substantial changes of biochemical traits across vegetative propagation treatments in field trial. Rooting-growing conditions during vegetative propagation had also an impact on coefficients of genotypic variation and heritability in hybrid poplar clones when grown in field trials.

Isolation and Characterization of Bacillus velezensis EB14, an Endophytic Bacterial Strain Antagonistic to Poplar Stem Canker Pathogen Sphaerulina musiva and Its Interactions with the Endophytic Fungal Microbiome in Poplar

Species of the genus Populus (commonly known as poplar) are one of the most widely used groups of forest trees in North America and Europe, and play a significant ecological role as a pioneer species in boreal forests and as a dominant species in the riparian forests that serve as wildlife habitats and watersheds. Natural and artificial hybrids of poplar are being extensively used in commercial plantations. However, many hybrid poplar trees are susceptible to Sphaerulina musiva, the pathogenic fungus that causes leaf spots and stem cankers and limits the utility of hybrid poplar as a plantation tree. We isolated an endophytic bacterial strain, Bacillus velezensis EB14, from a Populus hybrid which showed a strong antifungal activity against S. musiva. Through mass spectrometric analyses of cocultured B. velezensis EB14 and S. musiva, we identified five cyclic lipopeptides produced by B. velezensis EB14: iturin A1, iturin A2, iturin A9, subtulene A, and fengycin. In addition, B. velezensis EB14 produced four major unidentified compounds in cocultivation with S. musiva. The cyclopeptide production by B. velezensis EB14 was more pronounced (20- to 1,000-fold) in the cocultured plates due to elicitation by S. musiva. We also discovered that the native endophytic B. velezensis EB14 strain exhibited different levels of interactions against the endophytic fungal microbiomes of Populus sp. Overall, our results indicate that B. velezensis EB14 strain as a promising biocontrol agent that could be used against stem canker and leaf spot diseases caused by S. musiva in poplar plantations. [Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Hydraulic efficiency at the whole tree level stably correlated with productivity over years in 9 poplar hybrids clones

The rapid growth of trees is largely dependent on the efficient water transport system. Here, we assessed the reliability of breeding high-yield Populus hybrids clones via xylem hydraulic efficiency. Leaf-specific hydraulic conductance at four levels (stem-segment, shoot, root, whole-plant) and growth performance (aboveground biomass, growth rate) were investigated over three successive years on 1–3 years old plants of nine clones issued from I-101 (Populus alba) × 84 K (P. alba × P. tremula var. glandulosa). Gas exchange and leaf water status were also tested the last year. We found significant variations in the nine clones of most of the variables. At the end of the studied period, nine clones reached an average height of about 7.2 m. There was a maximum two-fold difference in aboveground biomass among clones, and the clone ranking for productivity was extremely stable over time. Higher hydraulic efficiency favors more stomata opening and better leaf water status. Hydraulic efficiency at four levels showed a broad positive correlation with productivity for three years; however, the correlation at stem-segment level became weaker year by year, while the correlations at large levels (shoot, root, whole-plant) remained stable over years. Our results suggest that hydraulic efficiency at the large plant level may better reflect the productivity of poplar hybrids than stem-segment in many years of growth, thus it may provide useful information for the breeding of high-yield poplar clones.

Ectomycorrhizal fungal communities differ among parental and hybrid Populus cross types within a natural riparian habitat

Plant hybridization is common and important in ecological and economic contexts, however little is known about the impact of plant hybridization on ectomycorrhizal fungal (EMF) communities in natural habitats. We used a Populus hybrid system ( P. angustifolia x P. fremontii ) in a heterogeneous riparian landscape to address the hypothesis that EMF communities differ among hybrids and their parental species (cross types). Several key results emerged. (1) Cross type influenced EMF composition, with communities on hybrids being distinct from their parents. (2) Cross type influenced the composition of hyphal exploration types important for soil resource foraging, although contact and short distance exploration types were dominant on all cross types. (3) Cross type had a marginal influence on EMF colonization, with P. angustifolia highest and P. fremontii lowest. These results highlight the potential for tree hybridization to structure belowground communities in heterogeneous natural ecosystems.