Deltoides Marsh Research Articles

First record of leaf miner, Phyllocnistis unipunctella (Stephens, 1834) (Lepidoptera, Gracillariidae) infesting Populus deltoides Marsh (Salicaceae) in Jammu and Kashmir, India

The study reports infestation of leaf miner Phyllocnistis unipunctella (Stephens, 1834) (Lepidoptera, Gracillariidae) on Populus deltoides Marsh (Salicaceae) in the UT of Jammu and Kashmir, India. The serpentine mining of leaves by larvae caused the leaves to dry out and turn brown, which lead to premature leaf drop, especially in severe infestations. Large populations rendered a silvery hue to the appearance of infested poplars when viewed from a distance. Pupation occurred inside the mine within a silken cell. Adults emerged after a period of 10-14 days. The infestation by this moth on poplars in the field was observed from the month of July to September.

Forest plantation diversification with Leguminosae tree species: Consequences on litter decomposition and nutrient recycling

AbstractMixed tree plantations provide greater ecosystem services than monocultures. Leguminosae tree species can be appropriate complements to achieve a sustainable soil management target. A key aspect of species trait complementarity is the litter mixture effects in the litter decomposition process. We evaluated how the mixture of poplar litter (Populus deltoides Marsh.) with Leguminosae tree species modulated the litter decomposition process and C, N and P recycling, through changes driven by the Leguminosae litter chemical traits. Under field conditions, we compared poplar litter alone (monoculture) with its 50:50 mixture with Enterolobuim contortisiliquum (Vell.) Morong., or Peltophorum dubium (Spreng.). Compared to poplar litter, its mixture with E. contortisiliquum had a 25% lower C:N ratio and a similar N:P ratio, whereas mixture with P. dubium had a 9% lower C:N and a 29% lower N:P ratios. The mixture with E. contortisiliquum showed a 64% faster decomposition rate, and 55% and 203% faster C and N release rates, respectively, compared to poplar. In contrast, in the mixture with P. dubium, there was no difference in the litter, C and N decay rates with poplar litter alone. The mixture with P. dubium had a 37% lower P retention compared to poplar, whereas P was released rather than retained in the mixture with E. contortisiliquum. The mixture with E. contortisiliquum showed a net antagonistic effect in the litter decomposition rate. However, in the mixture, poplar litter decomposed 33% faster and the E. contotrtisiliquum litter decomposed 35% slower than species alone. The C:N and N:P ratios in the litter mixture were relevant traits shaping the magnitude and direction of litter decomposition and nutrient recycling processes. The incorporation of both Leguminosae to monospecific poplar plantations could contribute to counteract P limitation in this system and to improve soil fertility and functioning.

Morphological, physiological, and transcriptional responses to low nitrogen stress in Populus deltoides Marsh. clones with contrasting nitrogen use efficiency

BackgroundNitrogen (N) is one of the main factors limiting the wood yield in poplar cultivation. Understanding the molecular mechanism of N utilization could play a guiding role in improving the nitrogen use efficiency (NUE) of poplar.ResultsIn this study, three N-efficient genotypes (A1-A3) and three N-inefficient genotypes (C1-C3) of Populus deltoides were cultured under low N stress (5 μM NH4NO3) and normal N supply (750 μM NH4NO3). The dry matter mass, leaf morphology, and chlorophyll content of both genotypes decreased under N starvation. The low nitrogen adaptation coefficients of the leaves and stems biomass of group A were significantly higher than those of group C (p < 0.05). Interestingly, N starvation induced fine root growth in group A, but not in group C. Next, a detailed time-course analysis of enzyme activities and gene expression in leaves identified 2062 specifically differentially expressed genes (DEGs) in group A and 1118 in group C. Moreover, the sensitivity to N starvation of group A was weak, and DEGs related to hormone signal transduction and stimulus response played an important role in the low N response this group. Weighted gene co-expression network analysis identified genes related to membranes, catalytic activity, enzymatic activity, and response to stresses that might be critical for poplar’s adaption to N starvation and these genes participated in the negative regulation of various biological processes. Finally, ten influential hub genes and twelve transcription factors were identified in the response to N starvation. Among them, four hub genes were related to programmed cell death and the defense response, and PodelWRKY18, with high connectivity, was involved in plant signal transduction. The expression of hub genes increased gradually with the extension of low N stress time, and the expression changes in group A were more obvious than those in group C.ConclusionsUnder N starvation, group A showed stronger adaptability and better NUE than group C in terms of morphology and physiology. The discovery of hub genes and transcription factors might provide new information for the analysis of the molecular mechanism of NUE and its improvement in poplar.

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.

&lt;strong&gt;&lt;em&gt;Stagonosporopsis rhizophilae sp. nov.&lt;/em&gt; (Didymellaceae, Pleosporales), a new rhizospheric soil fungus associated with &lt;em&gt;Populus deltoides&lt;/em&gt; Marsh&lt;/strong&gt;

In this work we describe Stagonosporopsis rhizophilae sp. nov. (Didymellaceae, Pleosporales, Ascomycota), a new species isolated from the rhizospheric soil of Populus deltoides Marsh. Phylogenetic analyses based on combined multilocus sequences of internal transcribed spacers (ITS: ITS1, 5.8S, ITS2), and partial sequences of the large subunit 28S nrDNA region (LSU), β-tubulin (TUB), and RNA Polymerase II second-largest subunit (RPB2) clearly place this species within the genus Stagonosporopsis but distinguishes it from all known and closely related species such as S. nemophilae. Stagonosporopsis rhizophilae sp. nov. can also be differentiated from S. nemophilae by morphological characters and by the negative response of the NaOH spot test for the production of metabolite E.

COMPARATIVE STUDY OF FLAVONOID COMPOSITION OF LEAVES OF PHARMACOPEIAL SPECIES OF THE GENUS POPULUS

The comparative study of the flavonoid composition of leaves of black poplar (Populus nigra L.), balsamic poplar (Populus balsamifera L.), canadian poplar (Populus deltoides Marsh.) and laurel poplar (Populus laurifolia Ledeb.) was held to determine the most perspective species as source of biologically active compounds. Nowadays poplar buds are registered as pharmacopeial medicinal raw material with antimicrobial, antifungal, anti-inflammatory and wound healing effects. It is also known that poplar leaves are used in folk medicine as an analgesic, antibacterial and anti-inflammatory agent. The leaves are also considered to be a perspective medicinal plant raw material along with buds. As a result of the comparative chromatographic analysis using detection at a wavelength of 366 nm and an alcoholic solution of aluminum chloride (AlCl3), rutin was found in all investigated extracts from the leaves of pharmacopeial species of poplars. Moreover, in extracts from Populus balsamifera L. and Populus laurifolia Ledeb. was revealed the presence of pinostrobin. It was determined that in all UV spectra of extracts from the leaves of the investigated poplar species, a long-wave batochromic shift were observed in the presence of 3% alcohol solution AlCl3, which indicates the presence of flavonoids. In the conditions of differential spectrophotometry, the maximum absorption in the range of 406–412 nm was observed, which indicates the necessity of using rutin standard which have maximum absorption at a wavelength of 414±2 nm. The content of the total flavonoids at the wavelength of 414 nm calculated on rutin in all samples was determined, which varies from 2.04% to 4.61% and corresponds to the recommended lower limit of the content of the total flavonoids (not less than 2.0%).

Physiological and transcriptomic analysis of yellow leaf coloration in Populus deltoides Marsh.

Populus deltoides Marsh has high ornamental value because its leaves remain yellow during the non-dormant period. However, little is known about the regulatory mechanism of leaf coloration in P. deltoides Marsh. Thus, we analyzed the physiological and transcriptional differences of yellow leaves (mutant) and green leaves (wild-type) of P. deltoides Marsh. Physiological experiments showed that the contents of chlorophyll (Chl) and carotenoid were lower in mutant leaves, and the flavonoid content did not differ significantly between mutant and wild-type leaves. Transcriptomic sequencing was further used to identify 153 differentially expressed genes (DEGs). Functional classifications based on Gene Ontology enrichment and Genome enrichment analysis indicated that the DEGs were involved in Chl biosynthesis and flavonoid biosynthesis pathways. Among these, geranylgeranyl diphosphate (CHLP) genes associated with Chl biosynthesis showed down-regulation, while chlorophyllase (CLH) genes associated with Chl degradation were up-regulated in yellow leaves. The expression levels of these genes were further confirmed using quantitative real-time PCR (RT-qPCR). Furthermore, the estimation of the main precursors of Chl confirmed that CHLP is a vital enzyme for the yellow leaf color phenotype. Consequently, the formation of yellow leaf color is due to the disruption of Chl synthesis or catabolism rather than flavonoid synthesis. These results contribute to our understanding of mechanisms and regulation of leaf color variation in poplar at the transcriptional level.

Structure of litter macrofauna communities in poplar plantations in an urban ecosystem in Ukraine

The litter macrofauna of 8 plantations of Populus italica (Du Roi) Moench, P. deltoides Marsh. and P. alba L. was studied in the city of Dnipro. The invertebrates were taken by manual sifting of litter from experimental plots of 8 m 2 . The total number of litter macrofauna in the poplar plantations varied from 8 to 187 specimen/m 2 , on average 53 specimen/m 2 . The greatest variety of species was obtained from a white poplar plantation with common hop and an elm-poplar plantation with bare soil and Amorpha fruticosa L. bushes (15 and 9 species correspondingly). The ma ximum readings on the Shannon–Weaver diversity index come from the abovementioned areas (3.2 and 2.9 bits respectively). The highest number of zoophages (40%) was obtained from the white poplar plantation with common hop. There was great consistency in the species composition across the plots, with the same 60 species (more than 50% of the total number of species of litter macrofauna recorded in the study) being found in 7 out of the 8 study plots. The share of species rare for any given ecosystem exceeded 10% in only 2 out of the 8 plantations studied. The dominant group in the size structure of the litter macrofauna of the poplar plantations (44–96%) was invertebrates of 4–7 mm length. In 5 out of 8 poplar plantations no species over 15 mm in length were found. This indicates the degraded size structures of the litter macrofauna communities. In taxonomic structure the dominant groups were Formicidae, Pulmonata, Porcellionidae, Lygaeidae, Julidae, Silphidae, Araneae, Carabidae, Staphylinidae. The results obtained indicate the low variety and degradation of the trophic and size structure of the litter macrofauna of these urban poplar plantations, which are subject to lack of moisture.

Dibenzo-α-pyrones: a new class of larvicidal metabolites against Aedes aegypti from the endophytic fungus Hyalodendriella sp. Ponipodef12.

In our search for new agrochemicals from endophytic fungi, the crude extract of the endophytic Hyalodendriella sp. Ponipodef12 associated with the hybrid 'Neva' of Populus deltoides Marsh × P. nigra L. was found to possess larvicidal activity against Aedes aegypti. Fractionation of the extract has led to the isolation of 11 dibenzo-α-pyrones (1-11), including three new congeners: hyalodendriols A-C (1-3). The structures of the new compounds were elucidated by comprehensive spectroscopic analyses, including the modified Mosher's method for the assignment of the absolute configuration. Compounds 2-7 showed potent larvicidal activities against the fourth-instar larvae of A. aegypti with IC50 values ranging from 7.21 to 120.81 µg mL-1 . Among them, penicilliumolide D (6) displayed the strongest activity (IC50 = 7.21 µg mL-1 ). A structure-larvicidal activity relationship was discussed. The possible mode of action of these compounds was assessed for their acetylcholinesterase inhibitory activities. In addition, hyalodendriol C (3) displayed antibacterial activity against Bacillus subtilis and Xanthomonas vesicatoria, and exhibited strong inhibition against the spore germination of Magnaporthe oryzae. Our study revealed dibenzo-α-pyrones to be a new class of larvicidal metabolites against A. aegypti. © 2016 Society of Chemical Industry.

Agrobacterium-mediated genetic transformation of Populus deltoides marsh clone G48 with gus and npt-II genes

Agrobacterium-Mediated Genetic Transformation of Populus deltoides Marsh Clone G48 with gus and npt-II Genes The present investigation had been carried out to standardize a protocol for Agrobacterium- mediated gene transfer in Populus deltoides Marsh. Clone G48 using petiole explants. Reproducibility of already standardized regeneration protocol for clone G48 had been evaluated. High frequency shoot regeneration (72%) from petiole explants was obtained on MS medium supplemented with 0.5 mg l-1 BAP, 0.2 mg l-1 IAA and 15 mg l-1 adenine sulphate. Root regeneration (100%) in in vitro developed shoots was obtained on MS medium supplemented with 0.1 mg l-1 IAA. Increasing concentrations of kanamycin (10-50 mg l-1) were given to find out the minimum dose of kanamycin required for the selection of putative transformed cells during genetic transformation. It was observed that a doze of 50 mg l-1 kanamycin inhibited callus formation and shoot regeneration and the explants turned brown and started dieing. This concentration of kanamycin would be the most useful for selection of npt-II gene transformed petiole cells/ tissues. Disarmed Agrobacterium tumefaciens LBA 4404 strain containing a reporter β-glucuronidase (gus) gene in binary vector pBI 121 along with kanamycin resistance gene (npt-II) was used for genetic transformation experiments. Only the transformed cells/ shoots were able to grow on selective shoot regeneration medium containing 50 mg l-1 kanamycin, whereas control explants did not survive. Regenerated putative transgenic shoots were subjected to transient gene expression analysis using spectrophotometric GUS assay and were found positive. This genetic transformation protocol will provide a platform for genetic manipulation of P. deltoides clone G48 for incorporation of genes governing various silviculturally important traits in future....

Pollen variation as a response to hybridisation in Populus L. section Aigeiros Duby

Interspecific hybrids often produce extensive gametic variation due to poor chromosome pairing and unbalanced chromosome segregation. To elucidate the influence of interspecific hybridisation on pollen variation in Populus L., we compared pollen size among three P. deltoides Marsh. clones, two P. nigra L. clones, and three P. deltoides × P. nigra hybrids and investigated the cytological mechanism of pollen variation by observing meiotic chromosome behaviour and microtubules. The frequency of shrunken and unstainable pollen grains was higher in the hybrids (15.54–57.28 %) than in the non-hybrid clones (0.98–4.82 %). The distribution of stained pollen size ranged more broadly in the hybrids than in the non-hybrids, suggesting that hybridisation increases pollen size variation. Precocious chromosome migration and lagging chromosomes were common in the hybrids, indicating poor chromosome pairing. Some micronuclei formed minispindles in metaphase II and emanated secondary nuclear-based radial microtubule systems in telophase II, undergoing cytokinesis to develop into microcytes in the meiotic products. Eliminated micronuclei might result in the formation of aneuploid pollen. The frequency of sporads with microcytes was higher in the hybrids (3.19–11.08 %) than in the non-hybrids (0–0.94 %). Disoriented spindles, including fused and tripolar spindles, led to the formation of dyads and triads, contributing to unreduced pollen production. These results provide new insights into the gametic variation of Populus interspecific hybrids and reveal several 2n pollen producers, which will be valuable in polyploid breeding of the section Aigeiros Duby.

A comparative study on heavy metal content of plants irrigated with tap and wastewater

The objective of the present study was to compare the potential accumulation capacity of Cr, Cu and Zn in Zea mays and Populus deltoides Marsh. The study was conducted in an area in a wastewater treatment plant in Birjand for a period of 120 days. The soil sample and selected parts of Z. mays and P. deltoides Marsh were collected monthly and treated with hydrochloric acid and nitric acid. The results showed that the highest mean concentrations of Cu (1.78 ± 0.93 mg kg−1) and Zn (2.65 ± 1.37 mg kg−1) were observed at Z. mays in September. The results indicated that the concentrations of Cu and Zn in Z. mays and P. deltoides Marsh shoots irrigated with wastewater were higher than tap water. In addition, both the plants comparatively showed a significant increase in total metal amount when treated with wastewater (p < 0.001). The study of BCF and TF demonstrated that Z. mays was suitable for phytoextraction of Cu, but unsuitable for both phytoextraction and phytostabilization of Zn and Cr, whereas P. deltoides Marsh was unsuitable for both phytoextraction and phytostabilization of Zn, Cu and Cr.

Separation and purification of bioactive botrallin and TMC-264 by a combination of HSCCC and semi-preparative HPLC from endophytic fungus Hyalodendriella sp. Ponipodef12

Two dibenzo-α-pyrones, botrallin (1) and TMC-264 (2) were preparatively separated from crude ethyl acetate extract of the endophytic fungus Hyalodendriella sp. Ponipodef12, which was isolated from the hybrid 'Neva' of Populus deltoides Marsh × P. nigra L. using a combination of high-speed counter-current chromatography (HSCCC) and semi-preparative HPLC. Botrallin (1) with 74.73% of purity and TMC-264 (2) with 82.29% of purity were obtained through HSCCC by employing a solvent system containing n-hexane-ethyl acetate-methanol-water at a volume ratio of 1.2:1.0:0.9:1.0. It was the first time for TMC-264 (2) to be isolated from this fungus. TMC-264 (2) showed strong antimicrobial and antinematodal activity, and botrallin (1) exhibited moderate inhibitory activity on acetylcholinesterase.

Fitness dynamics within a poplar hybrid zone: I. Prezygotic and postzygotic barriers impacting a native poplar hybrid stand.

Hybridization and introgression are pervasive evolutionary phenomena that provide insight into the selective forces that maintain species boundaries, permit gene flow, and control the direction of evolutionary change. Poplar trees (Populus L.) are well known for their ability to form viable hybrids and maintain their distinct species boundaries despite this interspecific gene flow. We sought to quantify the hybridization dynamics and postzygotic fitness within a hybrid stand of balsam poplar (Populus balsamifera L.), eastern cottonwood (P. deltoides Marsh.), and their natural hybrids to gain insight into the barriers maintaining this stable hybrid zone. We observed asymmetrical hybrid formation with P. deltoides acting as the seed parent, but with subsequent introgression biased toward P. balsamifera. Native hybrids expressed fitness traits intermediate to the parental species and were not universally unfit. That said, native hybrid seedlings were absent from the seedling population, which may indicate additional selective pressures controlling their recruitment. It is imperative that we understand the selective forces maintaining this native hybrid zone in order to quantify the impact of exotic poplar hybrids on this native system.

Soil nutrient status, nutrient return and retranslocation in poplar species and clones in northern Iran

Abstract: In this study several same-aged poplar species and clones were selected including Populus deltoides Marsh. CV. “Lux” (P.d “Lux”), Populus deltoides Marsh. CV. “Harvard” (P.d “Harvard”), Populus x canadensis Moench “Triplo” (P.xc “Triplo”), Populus x canadensis Moench “I-45/51” (P.xc “I-45/51”), planted in poplar research station about 20 years ago in the north of Iran, and Populus caspica Bornm. (P. caspica) as endemic and endangered poplar species. Some quantitative characteristics of the trees and soil samples were taken based on completely randomized block design. Samplings of live and senescent leaves were carried out in two-stages, mid-summer during the peak nutritional activities of trees and mid-autumn for senescent leaves. Soil samples were analyzed to determine organic carbon (OC), total nitrogen (N), available phosphorus (P) and exchangeable potassium (K). OC, total of N, P and K were also determined in live and senescent leaves. The results showed that P.d “Harvard” had the highest total height, DBH and diameter of crown compared to the other species and clones. The amount of OC, N and P in soil and live leaves of P.d “Harvard” clone are more than those of the other species and clones. OC, N, P, and K returned by senescent leaves were higher and lower for P.d “Harvard” and P. caspica respectively. P retranslocation for all of the clones and species was higher compared to N and K. The highest retranslocation percentage was observed in P. caspica (N=18.93, P=39.63, K=24.02) and the lowest (N=12.09, P=32.46, K=21.14) in P.d “Harvard” clone. It could be concluded that poplar species and clones have different nutritional requirements and retranslocation capabilities. It appears that P.d “Harvard” clone showed higher quantitative growth it could be beneficial for maintaining the soil nutrient status for successive plantings.

Isolation and characterization of a mycorrhiza helper bacterium from rhizosphere soils of poplar stands

If mycorrhizal formation could be enhanced by co-inoculation with mycorrhiza helper bacteria (MHB) which promote rapid root colonization by specific ectomycorrhizal fungi, this would be of advantage to the poplar forest industry. A number of poplar rhizobacterial strains were isolated from 11 regions of the eastern China. Four of the isolates, SY15, DZ18, HLJ4, and PY10, were characterized as MHB potential strains based on their positive effect on growth of ectomycorrhizal fungi Pisolithus tinctorius (Pers.) and Lactarius insulsus (Fr.). Under greenhouse conditions, one of the bacterial isolate, DZ18, significantly promoted the poplar trees growth and ectomycorrhizal colonization of P. tinctorius and L. insulsus on Populus deltoides Marsh. In contrast, the other three isolates SY15, HLJ4, and PY10 promoted fungal growth in vitro experiments but did not enhance ectomycorrhizal (ECM) formation in the greenhouse experiment. Therefore, it was concluded that DZ18 can be considered as an MHB strain. DZ18 was identified as Bacillus sp. based on morphological, physiological, and biochemical analyses in combination with analysis of 16S rDNA gene sequences.

Benzopyranones from the Endophytic Fungus Hyalodendriella sp. Ponipodef12 and Their Bioactivities

The endophytic fungus Hyalodendriella sp. Ponipodef12 was isolated from the hybrid ‘Neva’ of Populus deltoides Marsh × P. nigra L. In this study, four benzopyranones were isolated from the ethyl acetate extract of Hyalodendriella sp. Ponipodef12, and identified as palmariol B (1), 4-hydroxymellein (2), alternariol 9-methyl ether (3), and botrallin (4) by means of physicochemical and spectroscopic analysis. All the compounds were evaluated for their antibacterial, antifungal, antinematodal and acetylcholinesterase inhibitory activities. 4-Hydroxymellein (2) exhibited stronger antibacterial activity than the other compounds. Palmariol B (1) showed stronger antimicrobial, antinematodal and acetylcholinesterase inhibitory activities than alternariol 9-methyl ether (3) which indicated that the chlorine substitution at position 2 may contribute to its bioactivity. The results indicate the potential of this endophytic fungus as a source of bioactive benzopyranones.

When exotic poplars and native Populus balsamifera L. meet on the Canadian Prairies: Spontaneous hybridization and establishment of interspecific hybrids

As the interest in plantations of fast-growing tree species increases, concerns regarding the possibility of gene flow between plantations of exotic trees and their wild relatives are being raised. In Canada, the Prairie ecozone provides a unique opportunity to examine spontaneous hybridization and the spread of exotic genetic material because of the historical introduction of large numbers of exotic poplar species and their hybrids. In this region, poplar shelterbelts bearing exotic components such as Populus laurifolia Ledeb. and Populus nigra L. have been in contact with the native populations of Populus balsamifera L. since the 19th century. Given the ability for poplar species to hybridize, the objective of this study was to estimate the rates of spontaneous hybridization between one common poplar cultivar planted in shelterbelts, ♂‘Assiniboine’ (♀‘Walker’ [♀Populus deltoides Marsh.×♂(P. laurifolia×P. nigra)]×♂P. deltoides), and its neighbouring native congener, ♀P. balsamifera, on two study sites. To distinguish the genetic contributions of the species under study, a set of 26 diagnostic single nucleotide polymorphisms (SNPs) representative of 23 genes was used. We genotyped 2116 seeds sampled from P. balsamifera and identified paternal alleles specific to P. laurifolia, P. nigra and P. deltoides, which are typical genetic components of poplar shelterbelts. Surprisingly, the highest hybridization rate (2.3%) was observed at the site where 100-year-old Russian poplar shelterbelts (P. laurifolia×P. nigra) were found. A preliminary study of the P. balsamifera stands established in an 8km radius around the study site confirmed introgression of P. laurifolia and P. nigra alleles at a rate of 4.6%. These results indicate that spontaneous hybridization between shelterbelts of exotic cultivars and native P. balsamifera does occur in the Canadian Prairies and that interspecific hybrids can establish and survive in this landscape. This study suggests that biological factors such as the genetic composition of the native population and the gender of the exotic cultivars should be taken into consideration in the management strategies of this ecozone.

Adaptation and morpho-physiology of three Populus deltoides Marsh. × P. nigra L. clones after preconditioning to prolonged waterlogging

The implementation of a management-protection program, using suitable cultivation practices, contributes to rehabilitating marginal areas prone to prolonged waterlogging and preserving biodiversity. Three hybrid poplar clones (‘I-488’, ‘Rimini’ and ‘D-64’) were tested to assess their degree of tolerance to waterlogging by imposing four water regimes over a 1 year period: control (C), non-preconditioned (NPr), and two levels of flood preconditioning (Pr10 and Pr20). During the 2nd year, waterlogging (1.9 ± 0.7 mg/l O2) was imposed on plants from NPr, Pr10 and Pr20 treatments for 60 days followed by drainage. Survival rate, dry mass production, net photosynthesis and relative damage to membrane structural integrity were evaluated. The treatment response varied among clones and levels of preconditioning. Less pronounced damage to ‘I-488’ clones in comparison to those of ‘Rimini’ and ‘D-64’ indicates its superior tolerance to waterlogging. Preconditioning treatments (Pr20) and, to a lesser extent (Pr10), significantly improved the ability of the clones to tolerate flooding, suggesting that the application of a Pr20 preconditioning treatment in the nursery before outplanting would give hybrid poplar clones the morpho-physiological advantages necessary to counteract the arduous conditions on inundated sites.

Botrallin from the endophytic fungus Hyalodendriella sp. Ponipodef12 and its antimicrobial activity

Bioassay-guided fractionation of the crude methanol extract of the mycelia from the endophytic fungus Hyalodendriella sp. Ponipodef12, associated with the hybrid 'Neva' of Populus deltoides Marsh × P. nigra L., led to the isolation of one compound coded as P12-1 which was identified as botrallin (1,7- dihydroxy-3,9- dimethoxy-4a-methyl-6H- dibenzo [b,d] pyran-2,6 (4aH) -dione) by spectroscopic and physicochemical means. The median inhibitory concentration (IC 50 ) and minimum inhibitory concentration (MIC) of botrallin against Bacillus subtilis were 98.47 μg/ml and 200 μg/ml, respectively. The IC 50 values of botrallin against spore germination of Magnaporthe oryzae and Botryosphaeria dothidea were 81.62 μg/ml and 110.02 μg/m, respectively. This is the first report about botrallin and its antimicrobial activity from the endophytic fungus Hyalodendriella sp. Ponipodef12 derived from Populus species. Key words : Poplar hybrid 'Neva', endophytic fungus, Hyalodendriella sp., botrallin, antimicrobial activity.